Drinking water 2012 · 2013. 7. 12. · Drinking water 2012 4 Chapter 1: Summary Chapter 1:...

Drinking water2012Public water supplies in the Western region of EnglandJuly 2013A report by the Chief Inspector of Drinking Water

Drin

king

water 2

01

2

Public water supplies in the W

estern region of England

PB 13951

Drinking Water Inspectorate | Nobel House, 17 Smith Square | London | SW1P 3JR | Tel: 0300 068 6400

www.dwi.gov.uk

Western reg ion

1

Drinking water 2012

Western region of England

Dr ink ing wate r 2012

2

Publ ished by

Dr ink ing W ater Inspectorate

Area 7e

9 Mi l lbank

c/o Nobel House

17 Smith Square

London

SW 1P 3JR

Tel: 0300 068 6400

Website: http: / /www.dwi.gov.uk

© Crown Copyr ight 2013

ISBN: 978-1-905852-73-4

Copyr ight in the typographical arrangement and des ign rests wi th the Crown.

This publ icat ion (exc luding the logo) may be reproduced f ree of charge in any

format or medium provided that i t is reproduced accurate ly and not used in a

misleading context . The mater ia l must be acknowledged as Crown copyr ight wi th

the t i t le and source of the publ icat ion spec if ied.

Western reg ion

3

Contents

Chapter 1: Summary 4

Chapter 2: Water supply arrangements 10

Chapter 3: Drinking water qual ity test ing 12

Chapter 4: Drinking water qual ity results 15

4.1 Microbiological qual ity 16

4.2 Chemical qual ity 26

Chapter 5: Drinking water qual ity events 46

Chapter 6: Technical audit act ivity 49

Annex 1: Further sources of information 57

Annex 2: Glossary and descript ion of standards 58

Annex 3: Drinking water qual ity events in the region 71

Annex 4: Planned drinking water quality improvements 85

Annex 5: Compet it ion in the water industry 87

Annex 6: Water company indices 89

Annex 7: Guidance and research publ ished by DWI 99

Annex 8: Locat ion of private water suppl ies 101

Dr ink ing Water 2012 is the annual repor t o f the Dr ink ing Water Inspecto rate and

compr ises reports cover ing publ ic and pr ivate water suppl ies .

Publ ic suppl ies – Th is par t descr ibes dr ink ing water qual i ty in the Western reg ion. The

Inspectorate a lso publ ishes a ser ies of companion reports fo r o ther reg ions of England

(Centra l and Easte rn, Northern and London and South East reg ions) and a separate

report fo r Wales.

Pr ivate suppl ies – A summary of in format ion on pr ivate water suppl ies i s reported fo r

England and Wales.

Al l par ts are avai lab le on the Inspectorate ’s websi t e ht tp : / /www.dwi .gov.uk


4

Chapter 1: Summary

Chapter 1:

Introduces the reader to the report and its contents.

Highlights changes in relat ion to water supplies and their nature or

quality.

Compares the drinking water quality performance of companies in

the region to the performance of the industry as a whole.

Summarises water qual ity events dur ing the year.

Highlights notable improvement programmes.

Summarises the outcome of audits dur ing the year.

Portrays trends in consumer contacts about drinking water qual ity.

Raises awareness of the latest research or guidance publ ished by

the Inspectorate.

Drinking water 2012 is the annual publicat ion of the Chief Inspector of

Drinking Water for England and Wales. I t is the 23rd report of the work of

the Inspectorate and presents information about dr inking water quality for

the calendar year of 2012. I t is published as a series of seven reports, f ive

of which cover publ ic water suppl ies and two descr ibe private water

suppl ies. This report is about publ ic water suppl ies in the Western region

of England.

Set out in this report are the key facts ab out the qual ity of the publ ic water

suppl ies in the Western region, which is served by seven water companies

del ivering suppl ies to over four and a half mil l ion consumers. The ar ea of

supply of each water company is shown in Figure 1 and the organisat ion

and nature of water suppl ies in the Western region is described in more

detai l in Chapter 2. In October 2012, there was a change in supply

arrangements in the region when SSE Water commenced supplying

propert ies in the Brewery Square development in Dorchest er. In addit ion,

local author ity registers for 2012 record that there were 14,433 private

water suppl ies in the Western region in 2012, similar to the 14,115

reported in 2011. The location of these private suppl ies is set out in a map

in Annex 8 of this report and detai led information about the regulat ion and

quality of private suppl ies can be found in the separate report entit led

Drinking water 2012 – Private water supplies in England.

Western reg ion

5

Figure 1: Water supply arrangements

The quality of publ ic water suppl ies in England in 2012 was very high with

only 0.04% of tests fai l ing to meet the European Union (EU) and nat ional

standards across the industry. This compares favourably to the 1.6% of

failures recorded for England and Wales as a whole in 199 1, the f irst year

af ter privat isat ion of the water industry, when regulat ion of drinking water

quality was f irst introduced. The situat ion in relat ion to the qual ity of

private water supplies in England remains less sat isfactory with 7.5% of

tests fail ing to meet the EU and nat ional standards in 2012. Nonetheless,

this f igure represents an improvement when compared to the 8.4% of tests

that failed in 2010, the year when report ing for private suppl ies was f irst

introduced.

Across England as a whole, all tests for 21 out of 39 parameters gave

satisfactory results. Those parameters exhibit ing failures are put into

context in Table 2, which shows whether fai lures occurred in publ ic

suppl ies or pr ivate supplies or both. I t also shows whether any failures

occurred in samples col lected f rom a publ ic bui lding. Chapter 3 sets out

in detai l the cause of , and act ions taken in response to , each of the

failures in the Western region.


6

Table 2: Parameters exhibiting one or more failure of a standard in

England

Parameter

Fai lure(s) of the standard reported in 2012

Public water suppl ies Private water supplies

Non-public buildings

Public buildings

Non-public buildings

Public buildings

Microbiological parameters

E.col i

Enterococc i

Chemical parameters

Aluminium

Ant imony

Arsenic

Benzo(a)pyrene

Boron

Bromate

Colour

Copper

Fluor ide

I ron

Lead

Manganese

Mercury

Nickel

Ni trate

Ni trate – works

Ni trate/Nitr i te Formula

Ni tr i te – tap

Odour

Taste

Pest ic ides 2,4-D Chlorpyr i fos Fluroxypyr Glyphosate MCPA Mecoprop-P Metaldehyde Metazachlor Propyzamide

Aldr in

Heptachlor

Heptachlor epox ide

Polycyc l ic aromat ic hydrocarbons

Selenium

Sodium

Tetrachloromethane

Tota l t r iha lomethanes

Turbid i ty 4NTU

Western reg ion

7

The results of test ing of public suppl ies in 2012 demonstrated that , overall ,

the qual ity of drinking water in the Western region was good. The f igure for

compliance with dr inking water standards was 99.98%, an improvement

compared to 2011, and above the industry average. The Inspectorate uses

a range of indices to assess the water qual ity performance of the

companies providing publ ic suppl ies. These indices 1 look in turn at water

treatment (process control and disinfect ion indices), service reservoir

integrity and network maintenance. Individual water company f igures are

set out in Annex 6 . In 2012, the f igures for the Western region were

unchanged apart f rom the process control index, which was lower than last

year and below the industry average. The other indices were at or above

the industry average and the overal l dr inking water quality index was

better than the industry f igure and all the f igures for all the other regions.

Figure 3 shows how the improvement in the overal l index of drinking water

quality for the region in 2012 was mainly attr ibutable to a reduction in ir on

failures reported by Bristol Water (16 in 2011, three in 2012) and Wessex

Water (three in 2011, none in 2012).

Figure 3: Company performance for the overall index of drinking water

quality index

99.94 99.95 99.96 99.97 99.98 99.99 100

Wessex Water

Veolia Water Projects

SSE Water

South West Water

Sembcorp Bournemouth Water

Cholderton and District Water

Bristol Water

2011

2012

In 2012, in England, there were 398 public water supply events notif ied to

the Inspectorate and there were 429 pr ivate water supplies where a Notice

1 Calculat ion method for indices is publ ished at

ht tp:/ /www.dwi.defra.gov.uk/about/annual - repor t/ca lculat ing- indices.pdf


8

was served by local author it ies. This ref lects the extent of the investigative

work by the Inspectorate or local author it ies in 2012.

As shown in Table 4, across the Western region, in 2012, there were more

public supply events affect ing water qual ity overal l (58 compared to 46 in

2011) and about half were of a type that necessitated a detai led

investigation by an inspector, s imilar to the industry overall. In 2012 , there

were no serious events affect ing consumers in the Western region and the

Inspectorate init iated no prosecut ions. Information about al l signif icant

events can be found in Annex 3 of the report.

Table 4: Events in England and Wales in 2012

Region

Risk assessment category (DWI)

Not signif icant /minor

Signif icant Serious/

major

2011 2012 2011 2012 2011 2012

Centra l and Eastern region 125 98 32 49 1 4

London and South East region 51 70 38 33 1 1

Nor thern region 23 16 47 69 - -

Western region 34 31 12 27 - -

Wales 18 20 7 19 - -

Industry total 251 235 135 193 2 5

Note: Four events a f fec ted both Eng land and W ales in 2012

In 2012, there were 145 pr ivate water suppl ies that required improvement

to safeguard water qual ity or suf f iciency in the Western region. One

notable pr ivate supply event occurred when residents reported an oily

taste in the water on a private estate, which was found to be due to a fuel

oi l del ivery being put in the wrong tank in error. Addit ionally, the

Inspectorate was involved in a protracted problem with a supply to a

counci l owned farm and other domest ic propert ies, where over t ime there

have been numerous r isks to the water supply associated with a storage

tank, pipes and catt le troughs, and an unresolved legal dispute over

responsibi l i t ies. Further information on both these case studies can be

found in Drinking water 2012 – Pr ivate water suppl ies in England.

Turning to planned improvements in dr inking water quality in the region,

during 2012, the Inspectorate conf irmed the need for improvements at two

of South West Water’s treatment works (Greatwell and Restormel) to

address r isks relat ing to iron, turbidity and pesticides. Companies in the

region are committed to complete the planned work summarised in Annex 4

during the AMP5 per iod (2010–2015).

During 2012, the Inspectorate carr ied out 1,183 audits of publ ic water

supply arrangements across the industry and 110 of these audits were in

the Western region with unsat isfactory f indings in f ive cases. In addit ion ,

Western reg ion

9

the Inspectorate investigated 49 consumer complaints of which three

(1 BRL, 2 SWT) were f rom consumers l iving in the Western region.

In 2012, the total number of consumer contacts to water companies about

the qual ity of drinking water was 3.4 per 1,000 populat ion in t he Western

region, which is above the industry average of 1.9. Also , dur ing the year,

the Inspectorate handled 322 requests for advice about private suppl ies

f rom local authorit ies across England and Wales and 32 of these enquir ies

were f rom the Western region. Consumer complaint case examples and the

outcome of technical audits can be found in Chapter 6 and detai ls of the

work of the Inspectorate in relat ion to pr ivate suppl ies can be found in the

companion report entit led Drinking water 2012 – Private water supplies in

England.

In 2012, the Inspectorate provided the water industry with guidance

on nine topics to enable companies to comply with the dr inking water

regulat ions. The Inspectorate also provided joint technical advice and

guidance with the Environment Agency relat ing to implementat ion of the

Water Framework Direct ive. In addit ion , 13 research studies were

published by the Inspectorate to support the carrying out of regulatory r isk

assessments. Annex 7 l ists al l of the guidance and research published by

the Inspectorate in 2012.

During 2012, Parl iament and the Welsh Government introduced changes

to the funding arrangements for the Inspectorate. From 2013 onwards, the

cost of drinking water regulat ion wil l be recovered f rom water companies.

Details of the charges and the charging arrangements are published on the

Inspectorate’s website. The f irst charges wi l l apply to regulatory work

descr ibed in Drinking water 2013 .


10

Chapter 2: Water supply arrangements

Chapter 2:

Identif ies the water supply companies in the region.

I l lustrates the water source and supply arrangements in the region .

Provides summary f igures describing the water supply assets and

stakeholders.

Seven water companies supply dr inking water in the Western region:

Bristol Water (BRL), Cholderton and Distr ict Water (CHO), Sembcorp

Bournemouth Water (SBW), South West Water (SWT) and Wessex Water

(WSX), including two inset appointees; Veol ia Water Projects (VWP)

suppl ies consumers in the Tidworth area and SSE Water (SSE) supply

consumers in Old Sarum, Sal isbury and in Brewery Square, Dorchester.

Figure 5: Map il lustrating sources of drinking water by zone across

the region

Western reg ion

11

Much of the water in the region is der ived f rom surface water (7 0%)

abstracted f rom rivers such as the Severn, the Hampshire Avon, Dart, Exe,

Fowey, Tamar and the Dorset Stour. There is a major transfer of water into

the region via the River Severn f rom reservoirs in Wales that provide half

the daily supply for consumers in England in the Br istol Water area.

Addit ional ly, the upland areas of Bodmin Moor, Dartmoor, Exmoor and the

Mendips are important catchments for water resources in the region.

Surface water is drawn from many reservoirs, including Chew Val ley Lake,

Clatworthy, Coll i ford, Roadford and Wimbleball. Groun dwater also provides

a valuable resource (27%) in the region, with m ost boreholes drawing

water f rom the chalk aquifer of the Wessex basin. The Permian and

Triassic sandstone aquifer in the Otter Val ley is a valuable groundwater

resource for East Devon. Cholderton and Distr ict Water is reliant

exclusively on the chalk aquifer of the Wessex basin. Across the region,

a small proport ion of water suppl ies (3%) can be drawn from either surface

or groundwater sources.

Private water suppl ies in the region are widely distr ibuted across the area,

but are more common in East Devon and East Cornwall. These private

suppl ies are more reliant on groundwater (80%) than the publ ic suppl ies

in the area (27%).

Figure 6 i l lustrates the location of private and public supply groundwater

abstract ion points in relat ion to the groundwater aquifers in the region.

Figure 6: Location of private and public supply groundwater

abstraction points


12

In 2012, SSE Water who already supply one site in the region, began

supplying 250 consumers at the new development at Brewery Square in

Dorchester. The company has purchased a bulk supply of water f rom

Wessex Water.

Summary facts about the drinking water supply infrastructure of the region

are given in Table 7 with outl ine geographical and demographic

information.

Table 7: Key facts about public and private water supply arrangements

in the Western region

Public supplies Private supplies

Population supplied Water supplied (l/day) Abstraction points Treatment works Service reservoirs Water supply zones Length of mains pipe (km)

4,553,680 1,174 million 348

147 814 189 36,146

Population supplied Water supplied (l/day) Approximate number of private water supplies Total number of local authorities

120,000 185 million

14,433

30

Water composition

Surface sources Groundwater sources Mixed sources

70% 27% 3%

Water composition

Surface influenced supplies Groundwater sources

20% 80%

Area of public supply

Cornwall, Devon, Dorset, Gloucestershire (part), Hampshire (part), Somerset and Wiltshire (part)

Number of local authorities with private supplies

26

Chapter 3: Drinking water quality testing

Chapter 3:

Explains the basis of the drinking water test ing programme.

Records the number of tests carr ied out by water companies.

Identif ies any def ic iencies in water test ing and how these have been

remedied.

Throughout 2012, water companies sampled drinking water across the

region to test for compliance with the dr inking water regulat ions. More than

one-third of the tests were carr ied out on samples drawn from consumers’

taps selected at random. For monitor ing purposes, company water supply

areas are divided into zones . Sampling in zones at consumers’ taps is r isk

Western reg ion

13

based with the number of tests being higher in zones with a large

populat ion (maximum 100,000). Other sample locations are water

treatment works and treated water (service) reservoirs. Col lect ively , the

seven water companies carr ied out a total of 612,526 tests during 2012.

Only 45 of these tests failed to meet the standards set down in t he

regulat ions or exceeded a screening value. This represents a signif icant

improvement when compared to 131 tests fail ing in 2011.

Table 8: Number of tests carried out by companies in the region

Company

Place of sampling

Number of

tests per

company

Estimate

of

populat ion

Water

treatment

works

Service

reservoirs

Consumers’

taps

(zones)

Br isto l W ater 25,274

(17) 50,864 (165)

49,530 (52)

125,668 1,201,000

Cholder ton and Distr ic t Water

656 (2)

317 (1)

385 (1)

1,358 3,000


14,344 (7)

5,994 (20)

19,668 (10)

40,006 432,000

South W est Water

48,631 (30)

84,160 (280)

74,798 (32)

207,589 1,671,000

SSE W ater 0

(0) 0

(0) 469 (2)

469 1,000

Veol ia W ater Projects Ltd

1,264 (2)

1,395 (6)

649 (1)

3,308 8,000

Wessex Water

71,696 (85)

91,633 (305)

70,799 (91)

234,128 1,237,680

Region overall

161,865 (143)

234,363 (777)

216,298 (189)

612,526 4,553,680

Numbers in b rackets re f lec t the number o f works , reservo i rs or zones operated by th at company

in the reg ion i n 2012 . Some companies a re perm i t ted to car ry out some tes ts on samples taken

f rom supply po in ts ra ther t han f rom consumers ’ taps .

The regulat ions set out the parameters to be tested for by water

companies. Most of the test ing is for parameters with a European or

national standard (Schedule 1 parameters) , however, water companies

are also required by the regulat ions to test for other indicator parameters

(Schedule 2 parameters). The regulat ions also lay down how many of

these tests must be done each year (Schedule 3) and the Inspector ate


14

checks that the water companies are meeting these sample f requencies .

Across the region in 2012 there was a minor shortfall in sample numbers .

A number of errors were noted with the compliance monitoring

arrangements for service reservoirs in the region.

In 2012, there were four service reservoirs where South West Water

col lected samples f rom a site that was out of service; in three cases the

service reservoirs were out of service for operational reasons , but another

was not in use throughout the whole year. Bristol Water reported one

reservoir as having been returned to service in October , but submitted no

sample results, the company also sampled another service reservoir when

it was drained for inspection. Wessex Water failed to provide sample

results for two service reservoirs at one site for one month and took no

samples f rom another af ter its return to service in August. Likewise , a

further reservoir was not sampled for the f irst nine months of the year and

yet another was sampled whi le it was out of supply in August. This picture

is strongly suggestive of endemic def ic iencies in communicat ions between

operat ional and sampling staff . This is unsatisfactory, not least because it

compromises the integrity of data used by the Inspectorate to report on

compliance by the UK with the European Union (EU) Dr inking Water

Direct ive. Companies are reminded of the importance of ensuring that

senior management has oversight of how drinking water monitoring

programmes are being managed in the wider interest.

When col lect ing samples f rom consumers’ taps water companies must

ensure that a proport ion is f rom taps located within publ ic buildings.

Table 9 shows the extent of this public bui lding monitor ing in the region

in 2012. I f a failure to meet a standard is found to be due to the nature,

conf igurat ion or maintenance of pipes or water f it t ings within a public

bui lding then it is mandatory for the water company to take enforcement

act ion, so that the publ ic bui lding owner remedies the problem. Detai ls

of failures and any enforcement act ion are descr ibed in Chapter 4.

A summary of the results of test ing by companies for all parameters can be

found on the DWI website (http:/ /www.dwi.gov.uk) and on the CD

accompanying this report.

Western reg ion

15

Table 9: Failures of standards in public buildings where action is required by building owners

Company Total tests at

consumers ’ taps Total tests at

publ ic buildings

Tests fai l ing to meet the standard at publ ic bui ldings

Br isto l W ater 49,530 635 0

Cholder ton and Distr ic t Water

385 69 0


19,668 375 0

South W est Water

74,798 5,523 3

SSE W ater 469 141 0


649 6 0

Wessex W ater 70,799 3,410 1

Total 216,298 10,084 4

Note: The tab le summar ises fa i lu res a t t r ibu ted to bu i l d ing wate r sys tems and requ i r ing ac t ion by a respons ib l e pe rson.

Chapter 4: Drinking water quality results

Chapter 4:

Provides details of tests fail ing to meet microbiological and chemical

standards.

Comments on the remedial act ion taken by the water company or t he

Inspectorate.

The key water quality results for the Western region are presented in two

tables, one showing the results for microbiological parameters (Table 10),

the other deal ing with chemical and physical parameters (Table 13). The

microbiological quali ty of water is discussed f irst. Companies report al l the

results of the tests on a monthly basis to the Inspectorate. Tables in Annex

6 descr ibe the drinking water quality performance indices of each company

that are calculated f rom subsets of these t est results.


16

Microbiological quality

To protect public health, microbiological standards have to be met at each

individual treatment works and service reservoir. The signif icance of the

individual test results for each microbiological parameter at each locat ion

var ies and a single posit ive result cannot be interpreted without other

information. Al l companies are expected to follow best pract ice as set out

in The Microbiology of Drinking Water publ ished by the Standing

Committee of Analysts (SCA) which can be found by vis it ing the

Environment Agency’s website (www.environment-agency.gov.uk).

Table 10: Microbiological tests The number of tests performed and the number of tests not meeting the standard

Parameter Current

standard

Total number of tests

Number of tests not meeting

the standard

Addit ional information

Water leaving water t reatment works

E.col i 0/100ml 22,745 3 SBW (1), SWT (2)

Col i form bacter ia 0/100ml 22,744 12 SBW (3), SWT (2), WSX (7)

Clostr id ium per fr ingens

0/100ml 5,438 5 SWT (3), W SX (2)

Turbid i ty1 1NTU 22,699 3 SBW (2), SWT (1)

Water leaving service reservoirs

E.col i 0/100ml 39,110 1 WSX (1)

Col i form bacter ia

0/100ml in 95% of tes ts

at each reservoir

39,110 21

BRL (1) , SBW (1), CHO (1),SWT (5), WSX (13) Al l 777 reservoirs in the region met the 95% compl iance ru le

Water sampled at consumers’ taps

E.col i 0/100ml 12,734 1 WSX (1)

Enterococc i 0/100ml 1,493 0

1Turb id i ty is a cr i t ica l contro l parameter for wate r t reatment and d is in fect ion.

E.coli at works and service reservoirs

In 2012, out of a total of 22,745 tests at works only three (1 SBW, 2 SWT)

contained E.col i and this organism was only detected in one ( 1 WSX) out

of 39,110 tests at service reservoirs. This is a marginal improvement

Western reg ion

17

compared to 2011 when there were f ive E.col i fai lures ( two at works and

three at service reservoirs) in the Western region.

On detect ing E.col i, companies are required to act promptly to protect

public health. Their immediate response when f inding E.col i at a works

is to sample again, and more widely, to conf irm that water being received

by consumers is safe. In 2012, all these addit ional tests gave satisfactory

results in al l cases and there were no subsequent E.col i failures.

E.col i was detected in a sample taken at Tott iford works (near Bovey

Tracey) in February. The east cel l of the treated water tank was out of use

at this t ime for cleaning and inspection following two col iform breaches in

2011. South West Water found nothing untoward in relat ion to treatment

and concluded the or iginal sample was not representat ive of water

entering supply by virtue of sampling errors . The Inspectorate has noted

that it is not uncommon for failures to occur at sites whe n maintenance

or other work is taking place and the fai lure to col lect a representat ive

sample means other r isks could have been missed.

In October, South West Water detected E.col i in a sample taken from

Allers works (near Tiverton). While a review of treatment found nothing

unusual, the company noted a period of heavy rainfal l the day before ,

which caused the works to shut down in response to raw water turbidity

alarms. This was the second event at this works in June tr iggered by the

detect ion of Cryptosporidium oocysts and notif ied to the Inspectorate

during 2012 (see Annex 3). Af ter the subsequent E.col i failure in October,

the Inspectorate concluded the situation at this s ite warranted further

investigation and a Notice requir ing enhanced monitor ing and other act ion

was put in place.

Sembcorp Bournemouth Water reported E.col i in a sample f rom Alderney

works ( in Bournemouth) during June and there was a further col iform

failure at this works in December . The Inspectorate has reported in

previous years on serious integrity issues at this site, where the slow sand

f i l ters are situated above the dis infect ion contact tank . There is a legal ly

binding programme of work in place to address the r isk and the site has

been the subject of enhanced monitor ing for two years. The Inspectorate

audited the site in July (see the Technical audit act iv ity sect ion). The root

cause of the problem at this site is the poor condit ion of the old concrete

structures and deal ing with the asset condit ion is proving an ongoing

challenge for the company. Following the failure in December , effort has

been focused on the treated water tanks.

A sample taken at Charmy Down tower (near Bath) was found to contain

E.col i in July. The Inspectorate was cr it ical of Wessex Water for fail ing

to notify this event . The company found that water dr ipping f rom the roof

of the tower could enter the sample bott le and concluded the failure was


18

not representat ive of water enter ing supply . When the Inspectorate audited

this s ite in October, a new relocated sampling arrangement was in place

(see Figure 11). This event is s imilar to a previous one reported in

Drinking water 2011 at Two Ash service reservoir. The Inspectorate

expects companies to be proactive about maintenance and refurbishment

of sample facil i t ies thereby minimising events caused by unrepresentat ive

samples.

Figure 11: new sample point kiosk installed after E.coli fai lure at

Charmy Down tower

In Drinking water 2011 i t was reported that af ter detect ing E.col i at St

Cleer works (near Liskeard) , South West Water planned to inspect the

treated water tank after enabling works to rep lace a pump at Bastreet

works. This inspection, in Apri l 2012, found a number of cracks in the

structure and af ter repairs and instal lat ion of a protect ive membrane the

company returned the tank to service .

Western reg ion

19

Table 12: Detection of E.coli and Enterococci at treatment works,

service reservoirs and consumers’ taps

Company

E.coli in water

leaving treatment

works

E.coli in water

leaving service

reservoirs

E.coli at consumers’

taps

Enterococci at

consumers’ taps

Br isto l W ater 0 – 3 ,591 0 – 8 ,479 0 – 3 ,241 0 – 387

Cholder ton and Dis tr ic t Water

0 – 92 0 – 53 0 – 12 0 – 4


1 – 1 ,794 0 – 999 0 – 1 ,104 0 – 100

South W est Water 2 – 6 ,898 0 – 14,029 0 – 4 ,495 0 – 380

SSE W ater 0 – 0 0 – 0 0 – 15 0 – 5


0 – 208 0 – 279 0 – 24 0 – 8

Wessex W ater 0 – 10,162 1 – 15,271 1 – 3 ,843 0 – 609

Region overal l 3 – 22,745 1 – 39,110 1 – 12,734 0 – 1 ,493

Note: Resu l ts are shown as the number o f pos i t i ve tes ts – the to ta l number o f tes ts .

Coliform bacteria at works

Testing for coliform bacteria gives reassurance that water entering the

supply was treated adequately to remove bacterial and viral pathogens.

Repeated occurrences of coliform bacteria in samples f rom the same

works in one year are thus of concern and require act ion to be taken.

In 2012, this situation occurred at two sites: Dur leigh New works (WSX)

and Alderney works (SBW).

Coliform bacteria were detected on f ive occasions at Durleigh New

treatment works (near Bridgwater) in July and August. Fol low -up samples

showed col iforms throughout the downstream network (Danesborough

zone). The works abstracts surface water stored in Dur leigh impoundment

reservoir and treatment comprises Dissolved Air Floatat ion (DAF)

coagulat ion, pressure f i l t rat ion, granular act ivated car bon (GAC) f i l t rat ion

and chlor inat ion. At the t ime Wessex Water failed to identify the cause , but

in October the company took the works out of supply for a more thorough

investigation of all stages of the process. Subsequently , the company


20

submitted an updated r isk assessment report showing an unacceptable

residual r isk of contaminat ion due to excess bui ld up of sludge in the DAF

stage. The company has devised an act ion plan to address this problem.

The Inspectorate is concerned that investigations of colif orm failures at

works of ten follow a routine protocol that is too narrow. Companies must

examine widely looking for all forms of evidence of sub -opt imal process

performance. When investigat ing a col iform failure in March , in a sample

col lected f rom Stanbridge works, Sembcorp Bournemouth Water found that

the sampling cabinet had been lef t open the previous day to give

contractors access to a power supply and water , and the kiosk had been

lef t in a dirty condit ion. The company took act ion to restr ict the access to

keys for sampling cabinets.

In response to a coli form detect ion in August, at Sutton Poyntz works near

Weymouth, Wessex Water improved the sampling facil i t ies at the works to

enable samples to be taken from both works outlets. In October, the

company raised the minimum level of water in the contact tank by 5%, an

act ion suggestive of the company recognising that the previous operat ing

regime had been def ic ient in relat ion to securing an adequate dis infect ion

contact t ime before water enters supply f rom this site. This wi l l be taken

into account during the Inspectorate’s forward programme of risk -based

technical audit .

Fai lures at Alderney works (Sembcorp Bournemouth Water) and South

West Water’s Al lers works and Tott iford works are discussed above (see

the E.coli at works and service reservoirs sect ion).

The Inspectorate has noted that col iform bacteria were found in 12

samples f rom treatment works in the Western region dur ing the year and

this information wi l l be taken into account during the Inspecto rate’s r isk -

based programme of technical audit .

Clostridium perfringens

This organism is a spore-forming bacterium that is exceptional ly resistant

to unfavourable condit ions in the water environment, such as extremes of

temperature and pH, and disinfect ion processes such as chlor inat ion and

ultraviolet (UV) l ight. I t is a normal component of the intest inal f lora of up

to 35% of humans and other warm-blooded animals. These character ist ics

make it a useful indicator of either intermittent or historical faec al

contamination of a groundwater source or the performance of a surface

water f i l t rat ion plant. The detect ion of any Clostr idium perfr ingens should

tr igger an invest igation by the water company.

In 2012, out of 5,438 samples taken in the region, f ive did not meet the

specif ied value (3 SWT, 2 WSX).

Western reg ion

21

Clostr idium perfr ingens was detected in a sample taken at Dotton works ,

near Sidmouth, in February. This follows two failures (E.col i and coliform

bacteria) in 2011 af ter which South West Water repaired leaks in the roof

of the treated water tank , instal l ing a new roof membrane and returning the

tank to service in December 2011. The Inspectorate is disappointed to

note this further failure only two months later . The subsequent company

act ion in March was to inspect, clean and disinfect the contact tank, a

telemetry duct was resealed as a precaut ion, but no cause for the failure

could be found. The Inspectorate is concerned that investigat ions of

microbiological fai lures at works of ten follow a rout ine protocol th at is too

narrow. Companies must examine widely, looking with an open mind and

be guided by the purpose of each indicator test; clostr idia usual ly or iginate

f rom raw water and, in this context, would point to historic faecal pollut ion

of groundwater.

South West Water also investigated detect ions of Clostr idium perfr ingens

at Restormel works (near Bodmin) and Crownhil l works (near Plymouth) in

Apri l. The invest igations found nothing untoward. The Inspectorate expects

that these unexplained failures should tr igger a review and update of the

regulatory r isk assessment for these sites.

A sample taken from a consumer’s tap in Wessex Water’s Maundown

Central zone (near Taunton) in June contained Clostr idium perfr ingens.

Further samples f rom the property, nearby propert ies, and upstream assets

gave sat isfactory results . The failure was probably an isolated instance of

a disturbance of historic deposits in the local distr ibut ion network. The

pract ice of sampling for Clostr idium perfr ingens at consumers’ taps is

becoming increasingly out of l ine with the rest of the industry. The

Inspectorate welcomes how other companies have amended their

monitor ing programmes, recognising the merit and benef it of the

Inspectorate’s advice.

A Clostr idium perfr ingens failure f rom a concessionary supply in Wessex

Water’s ‘Por lock – Domestic ’ zone near Minehead is discussed in the

E.col i and Enterococci at consumers ’ taps sect ion.

Turbidity at works

Turbidity is a measure of how much l ight can pass through water and

indicates the condit ion or ‘c loudiness’ of water. Turbidity is caused by

part ic les suspended in the water and is an important cr it ical control

measure of the performance of disinfect ion. Turbidity is measured at two

points in the water supply chain, at treatment works where a value of

1NTU appl ies and at consumers’ taps where the standard is 4NT U. The

following discussion focuses on the results of samples taken at treatment


22

works. The results of turbidity test ing at consumer s’ taps can be found in

the Maintaining water qual ity in distr ibut ion sect ion.

Turbidity in some groundwater sources is a consequence of inert clay or

chalk part icles or the precipitat ion of iron and other oxides when water is

pumped and air introduced. Turbidity in surface waters can be due to a

wide range of inert part iculate matter and is more l ikely to include

adherent biological matter and pathogenic microorganisms. Ir respect ive

of origin, turbidity can seriously interfere with the eff iciency of dis infect ion

and the purpose of many water treatment processes is directed at the

removal of part iculate matter before disinfect ion. The eff icacy of all types

of disinfect ion (chemical and physical) can be impaired unless turbidity of

below 1NTU is rel iably achieved and assured. Control is normally achieved

by cont inuous on- l ine turbidity monitor ing of raw water. In relat ion to the

removal of Cryptosporidium , i t was a key recommendat ion of the Bouchier

Report 2 that the performance of f i l ters be subject to cont inuous turbidity

monitor ing to minimise turbidity.

In the Western region there is one groundwater works (Stanbridge, SBW)

classif ied histor ical ly as being at r isk f rom the parasite Cryptospor idium

and dur ing 2012 it failed to meet the turbidity value of 1NTU.

There were two occasions when a turbidity value >1NTU was reported at

Stanbr idge works. In February, the company noted that there was

a tendency for turbidity to increase with changes in the duty pump ,

although the focus of attention at that t ime was on the accuracy of the

sample result ( later shown to be val id, see the Technical audit act iv ity

sect ion). Af ter the second high turbidity value in December, the fact that

the sample tap had been turned off , rather than lef t running, combined with

no adverse trends f rom the on-l ine monitors, led the company to conclude

the failure was not representat ive of water entering supply. The

Inspectorate was cr it ical of the l imited response to these fai lures. Turbidity

monitor ing is the cr it ical control measure for disinfect ion and

Cryptosporidium r isk at groundwater s i tes, therefore the Inspectorate

expects this to be taken into account in companies’ invest igations and also

tr igger a review and update of the supply r isk assessment.

2 Cryptospor id ium in Water Suppl ies – Third Report of the Group of Experts

to Depar tment of the Environment and the Regions and Department of Heal th.

Chairman: Ian Bouchier, November 1998 avai lable at

ht tp:/ /www.dwi.defra.gov.uk/research/bouchier/ index.htm

Western reg ion

23

In the Western region there is one surface water works classif ied as being

at r isk f rom the parasite Cryptosporidium and dur ing 2012 fai led to meet

the turbidity value of 1NTU.

At Wendron works (near Helstone), South West Water invest igated a

turbidity value of >1NTU in July. The company replaced the sample l ine

and pump to prevent unrepresentat ive turbidity results as a consequence

of a build up of l ime deposits. Although the company reported f inding

nothing untoward with treatment, the Inspectorate considered that the

l imited scope of the investigat ion meant that it provided no assurance

as to whether they addressed the cr it ical control measures for

Cryptosporidium r isk and the recommendations in the Bouchier report

for surface water works.

Coliform bacteria at service reservoirs

Testing for coliform bacteria gives reassurance that the qu al i ty of water

held at these strategic points in the distr ibut ion system is adequately

maintained. The national standard requires that at least 95% of samples

col lected f rom each service reservoir throughout one year are f ree f rom all

col iform bacteria 3. In 2012, al l 777 service reservoirs ( including water

towers) in the region met the standard.

In last year’s report, the Inspectorate reported on an increase in col iform

detections at service reservoirs by Br istol Water and noted that no cause

had been found in any of the f ive investigations . The Inspectorate are

pleased to see an improvement in col iform detect ions and subsequent

investigations by Bristol Water at reservoirs this year.

A col iform failure at Bristol Water’s Tetbury reservoir (near Gloucester)

in July was the second within 12 months. The reservoir was drained and

inspected in October reveal ing a crack and ingress around the access

hatch. Af ter repair the reservoir was returned to service . The Inspectorate

was cr it ical of Bristol Water’s service reservoir performance in Drinking

water 2011 and is pleased to note the improvement in 2012.

Cholderton and Distr ict Water detected col iforms in Cholderton service

reservoir in May. There was a problem with the chlor ine dosing equipment

( low chlorine residual) at the t ime due to a part ial ly blocked nozzle.

Wessex Water, on behalf of Cholderton and Distr ict Water, f i t ted a new

sealed weatherproof sample cabinet at the site.

Af ter Wessex Water found col iforms in a sample at Puncknowle service

3 Regulat ion 4(6)


24

reservoir (near Br idport) in February, a number of site improvements were

identif ied as necessary: rais ing upstands around hatches, improving hatch

covers and providing better seals, alterat ions to the sample point and

improving site secur i ty. These improvements were completed by the end

of June 2012. The Inspectorate expects that this fai lure should tr igger a

review and update of the regulatory r isk assessment for this si te.

Also in February, Wessex Water detected col iforms at Primrose Hil l

service reservoir (Bath) and discovered that the sample tap was leaking.

The sample tap and sample l ine were replaced. At Hilmarton service

reservoir (near Chippenham), af ter a coli form failure in March, a recently

instal led sample l ine was found to be too long and coi led around the

sampling cabinet. Yet another inappropr iately s ituated sample tap in poor

condit ion was found following a failure at Lodge Hil l service reservoir (near

Shepton Mallet) in August . Wessex Water relocated these sampling

facil i t ies in January 2013.

Two col iform bacteria failures in May, (Over Stowey service reservoir, near

Bridgwater and Tol ler Porcorum service reservoir, near Br idport) were

taken from sampling facil i t ies that were overgrown with brambles and the

col iform failure in June at Heathcombe service reservoir (near Bridgwater),

was f rom an unprotected sample point on the roadside that was overgrown

with vegetat ion. In 2012, the Inspectorate audited aspects of Wessex

Water’s programme to identify and upgrade poor sampling facil i t ies as part

of a series of themed audits across the industry (see the Technical audit

act iv ity sect ion).

Coliforms were detected in a sample taken at Lit t lemoor service reservoi r

in Weymouth in July. There was a failure at this s ite in 2011. Wessex

Water found nothing untoward on both occasions. The Inspectorate

expects companies to use unexplained failures to inform and update the

regulatory r isk assessment for the supply.

At Seend service reservoir near Trowbridge, in October, Wessex Water

investigated a col iform failure and, in addit ion to making improvements

to the sampling facil i t ies , ident if ied that a reservoir bypass valve was not

completely closed which could have led to back f low of stagnant water .

Remedial work was completed at this site in January 2013. In November,

Wessex Water detected col iforms at Lawn Barn RHS service reservoir,

near Dorchester, and found and f ixed potential ingress points around

conduits under an access hatch. Similarly , the investigation of a col iform

failure in December at Roomhill service reservoir (near Minehead) found

a leak on the inlet that was subsequent ly repaired. The Inspectorate

expects that these failures should tr igger a review and update of the

regulatory r isk assessments for these sites.

Western reg ion

25

Following a col iform failure in June, South West Water inspected and

cleaned Ollsbrim service reservoir . No ingress points were found, but the

company replaced the alkathene sample l ine pipework with stainless steel.

South West Water detected col iforms at three sites in August. At Roche

service reservoir (near St Austel l) the company relocated the outdoor

sample point to within a pump house on site. Parsonage service reservoir

(near Exeter) was inspected, c leaned and returned to service, as was High

Street No.1 service reservoir in St Austel l ; however, its condit ion was

suff icient ly poor that the company plan to abandon the structure in summer

2013 af ter commissioning a new trunk main to High Street service

reservoir No. 2.

In November, South West Water reported a col iform failure. I t was found

to be unrepresentat ive of water in supply at Gnaton service reservoir (near

Plymouth). The sample had been taken from the inlet of a downstream

service reservoir because the sample pump at Gnaton was faulty and it

was found that a further 12 compliance samples in the year were similarly

unrepresentat ive (see the Technical audit act iv ity sect ion for the

Inspectorate’s conclusions and recommendations fol lowing a series of

themed audits on sampling matters across the industry).

The Inspectorate has noted that col iform bacteria were found in 21

samples f rom service reservoirs in the Western region during the year and

this information wi l l be taken into account during the Inspectorate’s r isk -

based programme of technical audit .

E.coli and Enterococci at consumers’ taps

In 2012, a total of 12,734 consumers’ taps were tested for E.col i and one

was posit ive (1 WSX). There was no indication, f rom information gathered

by the water company, of a faecal contaminat ion event af fect ing other

propert ies in this zone. Like E.col i , the presence of Enterococci

is indicat ive of faecal contaminat ion and neither bacter ium should be found

in any sample. In 2012, the companies carr ied out 1,493 tests for

Enterococci at consumers’ taps; the organism was not present in any

sample.

Porlock Domestic zone near Minehead consists of a small number of

propert ies that receive a concessionary supply of raw water drawn of f from

the raw water main f rom Nutscale storage reservoir before it reaches

Porlock treatment works. To secure that these publ ic concessionary

suppl ies are wholesome, Wessex Water has instal led point of use

treatment at each property. In February, a sample taken from one property

in this zone was found to contain E.coli, col iform bacteria and Clostr idium

perfr ingens. This was notif ied to the Inspectorate as an event (Annex 3).


26

Wessex Water gave boi l water advice to the householder whi le carrying out

a f it t ings inspection. I t was found that a cross -connect ion had been made

bypassing the water treatment unit when a new shower had been f it ted.

A leak outside the property had been repaired at the same t ime. The

company disconnected the cross-connect ion, reinstated the treatment

system as designed, chlor inating the treatment unit and pipework , and

thoroughly f lushing the system. Following two sets of sat isfactory samples

the boil water not ice was l if ted. The situation was explained to the tenant

who was warned not to interfere with the treatment unit or its pipework

connections.

Chemical quality

The drinking water regulat ions set out the minimum test ing requirements

for all chemical and physical parameters. A full summary of the results of

test ing by each company, including the results for indicator parameters ,

is provided on the DWI website and on the CD accompanying this report.

The following text and Table 13 set out the results for those parameters

where there has been a failure to meet a European or national standard

(mandatory qual ity standards) and any other parameter of interest.

In addit ion, at the request of local author it ies, the results of test ing for

f luoride, iron, lead, manganese, nitrate, nitr ite, pesticides and radioact ivity

are given. The Inspectorate has also included instances where residual

chlorine results were reported at a level that may be considered

undesirable on grounds of consumer acceptabil i ty (2mg/l).

Western reg ion

27

Table 13: Chemical and physical parameters

The number of tests performed and the number of tests not meeting the standard

Parameter

Current standard or

specified concentration

1

Total number of tests

Number of tests not meeting

the standard

Additional information

Aesthetic parameters

– odour No abnormal

change

4,218 6 BRL (2), WSX (4)

– taste

4,179

6

BRL (1), SWT (1), WSX (4)

Aluminium 200μg/l 4,645 1 SWT (1)

Chlorine – residual (free)

2

2mg/l 74,173 2 CHO (1)

Chlorine – residual (total)

2

2mg/l 74,744 2 CHO (1), WSX (1)

Fluoride 1.5mg/l 1,203 0

Iron 200μg/l 4,398 7 BRL (3), SBW (1), SWT (3)

Lead (current standard) 25μg/l 1,482 2 SWT (1), WSX (1)

Lead (future standard) 10μg/l 1,482 10 BRL (3), SWT (4), WSX (3)

Manganese 50μg/l 4,395 2 SWT (2)

Nickel 20μg/l 1,478 2 SWT (1), WSX (1)

Nitrate 50mg/l 1,808 0

Nitrite 0.5mg/l 1,826 0

Pesticides – total 0.5μg/l 1,466 0

Pesticides – individual3 0.1μg/l 43,146 2

Metaldehyde BRL (1), WSX (1)

Radioactivity

Gross alpha 0.1Bq/l 457 1 BRL (1)

Gross beta 1Bq/l 453 0

Total indicative dose 0.10mSv/year 0 0

Tritium 100Bq/l 640 0

Trihalomethanes Total 100μg/l 1,475 2 SWT (1), WSX (1)

Notes: 1Current standard, specification or other screening value.

For comparison, 1mg/l is one part in a million, 1μg/l

is one part in a thousand million. 2The value of 2mg/l is a consumer acceptability value set by the Inspectorate.

3A further 3,893 tests were done for aldrin, dieldrin, heptachlor, heptachlor epoxide, all of which met the

relevant standard.


28

Aesthetic parameters

Aesthetic parameters: Taste and odour

Consumers expect their dr inking water to be clear and bright in

appearance and free from discernible taste or odour. In recognit ion of

this the regulat ions st ipulate national standards for colour, odour and

taste. Companies are required to investigate and remedy the cause of any

adverse result .

Taste and odour sampling results

Across the Western region, out of a total of 1,909 samples col l ected f rom

consumers’ taps just 12 exhibited a posit ive taste or odour. Al l tests in the

region met the standard for colour. The posit ive results are summarised

below in relat ion to their nature and cause as determined by the

investigations carr ied out by the companies. From this information it can

be seen that many were conf ined to a single property and did not ref lect

a wider problem in the water supply zone.

Bit ter/f lat /sweet: One (BRL): These descriptors relate to samples

where the tap water is art if ic ially sof tened; the remedy is to advise

the householder to draw water for drinking and cooking f rom the tap

connected direct ly to the mains (or to f it a mains fed tap if one does

not exist) . In July, Br istol Water detected a sweet odour in a sample

taken from the Patchway Bradley Stoke And Winterbourne supply

zone. The sample was thought to have been col lected f rom the

unsoftened dr inking water tap as indicated by the customer. Fol low

up samples taken before and af ter gave satisfactory results.

Oil/solvent: One (SWT): These descr iptors relate to situat ions where

there has been a spi l lage of central heat ing oil, petrol or diesel on

the property and this has permeated through the plast ic water supply

pipe; the remedy is to advise the householder on the need t o replace

the affected pipe and to safeguard against future spil ls. South West

Water perceived an oi ly/sharp taste in a sample f rom the Dotton

zone (Sidmouth) in August. Further samples were f ree f rom taste

and the company carr ied out a range of tests to rule out migrat ion of

petrol, oi l or similar substances.

Earthy/musty: Eight (WSX): These descr iptors relate to situations

where harmless, but object ionable, substances are produced by the

growth of algae in raw water storage reservoirs ; the remedy is

improved treatment/reservoir management by the company. Further

detai l on the Wessex Water failures can be found in the section

Chemical qual ity – Geosmin.

Western reg ion

29

Eggs: Two (BRL): This descriptor relates to situat ions where

hydrogen sulphide is produced in the water which may have become

stagnated by non-use or loss of the oxygen dissolved in the water ;

the remedy is to f lush away the stagnated water or to take out

components that are removing oxygen from the water. In November,

Bristol Water detected an odour describ ed as ‘eggs ’ or ‘m i ld eggs ’

in two samples taken from separate zones (Kingswood and

Mangotsf ield zones, Bristol). In one of these cases the occupier

conf irmed an in- l ine GAC f i l ter was instal led and they did not know

when the f i l ter had last been changed. The Inspectorate expects

companies to provide householders with a copy of the leaf let

Looking after water in your home

(http:/ /www.water.org.uk/Looking_after_water_in_your_home )

whenever staf f visit a premises for any reason.

Consumer contacts to water companies for taste and odour

When consumers experience a persistent taste or odour, they may contact

their water company to report the problem. Records of these contacts in

each zone are recorded by water companies and passed to the

Inspectorate annually. Figure 14 shows the zone-by-zone contact rate

per 1,000 populat ion across the Western region.

Figure 14: Rate of taste and odour contacts per 1,000 people


30

Figure 14 shows the location of taste and odour failures , and shows the

background level of consumer contacts for taste and odour across the

Western region. The map shows that there has been an increase in the

rate of consumer contacts in South West Water’s Bratton Fleming supply

zone, near Barnstaple. Many of the complaints were chlor inous, earthy o r

musty in nature. The Inspectorate has noted considerable var iat ion in the

chlorine residual concentrat ion at Bratton Fleming works, such variat ions

are of ten the cause of consumers report ing that water quality is

unacceptable. Four of Wessex Water’s zones showed similar ly high rates

of consumer contacts: Portesham (near Weymouth), Maiden Newton

(Dorchester), Chute (Andover) and Holton (Sherbourne). In addit ion , the

map shows high rates of consumer contacts in Br istol Water’s Berkeley

Marsh and Rodham Down zone suppl ied by Oldford works. Likewise, taste

and odour report rates were higher this year in the company’s North

Wooton, West Pennard and Boltonsborough zone, near Glastonbury. The

Inspectorate expects companies to look closely at consumer contacts as

part of the process of r isk assessment and take act ion to investigate and

address consumer acceptabi l i ty issues.

Aluminium

Aluminium can occur natural ly in some water sources. Also, aluminium-

based water treatment chemicals may be used at surface water works

to aid the process of f i l t rat ion.

In 2012, a total of 4,645 samples were tested for aluminium in the Western

region. All companies in the Western region achieved 100% compliance

with the aluminium standard except for South West Water which reported

that one test exceeded the standard (1 SWT).

During November, a sample taken from a public building in South West

Water’s Dousland supply zone, Tavistock, contained aluminium and

manganese in excess of the standards. Subsequent investigatory samples

were sat isfactory. Companies are reminded that the invest igation of a

failure of any parameter in a sample f rom a publ ic bui lding must be fully

documented because enforcement is mandatory under the EU Drinking

Water Direct ive. Where the cause is not due to the domestic pipework or

f it t ings within the property, as is l ikely in this instance, enforcement is for

the Inspectorate not the company. The senior management of companies

need to have close oversight of how drinking water monitor ing programmes

are being managed in the wider interest.

Western reg ion

31

Chlorine

Chlorine is widely used as bleach and has a long history of use in

circumstances where the maintenance of good hygiene is essential, for

example, food preparation, swimming pools and water suppl ies . In the UK,

levels of residual chlorine in tap water are very low, typical ly 0.1 – 0.5mg/l

and rarely exceed 1.0mg/l in water drawn from taps in premises . This

compares very favourably to the World Health Organisation (WHO) health-

related guide value of 5mg/l.

Water companies are required to measure residual chlor ine whenever

samples are col lected for microbiological analysis . Any abnormal change

in the level of residual chlor ine in a part icular supply must be invest igated.

The Inspectorate checks the act ion taken by companies in relat ion to any

chlorine result above 2mg/l. Across the region in 2012, there were two of

these abnormal results compared to 13 in 2011. The causes and act ions

taken by the companies are descr ibed below.

In August, Cholderton and Distr ict Water Company recorded a free chlor ine

residual at Cholderton service reservoir of 2.75mg/l. The company found

that the site operator had not carr ied out dai ly checks and therefore failed

to notice that there was a problem. The company ha s since retrained its

operators on the correct procedures. The company did not receive any

consumer contacts associated with the problem.

Wessex Water reported a value of 30mg/l total chlor ine in a sample

col lected f rom Leigh service reservoir in October. When the Inspectorate

challenged this result in the data return of the company, a data inputt ing

error was found (the actual result was 0.3mg/l).

In addit ion to invest igating any abnormal change in the level of residual

chlorine, water companies must also investigate and address a ny situation

where consumers report that tap water exhibits an object ionable chlorine

taste and odour. Companies therefore have in place protocols for

receiving, assessing and recording consumer contacts. Figure 1 5 maps the

chlorine taste and odour consumer contact rate per 1,000 populat ion for al l

zones in the Western region dur ing 2012.


32

Figure 15: Map il lustrating rates of chlorine-related consumer

contacts to water companies per 1,000 population

From Figure 15 it can be seen there was a relat ive ly high consumer

contact rate (>0.8 per 1,000 populat ion) across large areas of Devon and

Cornwall served by South West Water (nine zones), wel l in excess of the

industry average of 0.23 per 1 ,000 populat ion. Similarly , there were 11

zones across the Wessex Water supply area that exceeded this level , as

did Bristol Water’s North Wooton, West Pennard and Boltonsborough

supply zone (near Glastonbury). The Inspectorate has noted that chor ine

residuals f rom many of South West Water’s works are relat ively high

(>1mg/l) and exhibit considerable var iabi l i ty. The Inspectorate expects

companies to look closely at chlorine -related consumer contacts as part

of the process of r isk assessment and modify pol ic ies for residual chlor ine

management so as to address consumer acceptabi l i ty issues. This

information wi l l be taken into account dur ing the Inspectorate’s forward

programme of technical audit in the region.

Disinfection by-products

To ensure the microbiological safety of publ ic water suppl ies , water

companies are required to dis infect water at the treatment works before

supplying it through the distr ibut ion system to consumers. Disinfect ion may

be achieved by any appropr iate physical or chemical method, or a

combination of the two. The choice of method wil l depend o n a range of

Western reg ion

33

site-specif ic factors, but an important considerat ion is the requirement to

keep disinfect ion by-products (DBPs) to a minimum. This 1998 EU Drinking

Water Direct ive requirement was introduced formally into nat ional law in

January 2010.

Chemical disinfectants are powerful oxidants that react with organic and

inorganic matter in raw water to form other compounds known as DBPs.

There are many dif ferent DBPs and the l ikelihood of any part icular ones

occurring in a given water supply can be predicte d f rom the raw water

quality and the method of disinfect ion. A summary of commonly

encountered DBPs can be found in the WHO Guidel ines for Drinking Water

Qual ity 2004 , Sect ion 8.5.4. Based on current global research it is felt that

two groups of compound [ tr ihalomethanes (THMs) and haloaceticacids

(HAAs)] serve as indicators for monitor ing DBP performance overall.

The most appropr iate means of control l ing DBPs is removal of the organic

precursors f rom the raw water before it is dis infected.

The Inspectorate has made a general assessment of how well companies

in the Western region are meeting the DBP rule using water company THM

data reported for 2012. For this evaluation the Inspectorate has assumed

that a value of below 50µg/l, representing 50% of the standard, indicates

that, general ly, a company is minimising DBPs effect ively. Table 16 shows

the annual average value for the groundwater and surface water zones of

each water company in the region and Table 17 shows the zones which

exceed this screening criterion.

Table 16: Mean trihalomethane level in zones for groundwater and

surface water

Average trihalomethane levels in zones in 2012 (µg/ l)

Company Groundwater suppl ies Surface water inf luenced

suppl ies

Br isto l W ater 13 24


11 N/A


19 32

SSE W ater 8 21

South W est Water N/A 41

Veol ia W ater Projects 7 N/A

Wessex W ater 11 22

Industry average 10 30

Figures are for whole company areas.


34

Table 17: Numbers and names of zones exceeding an annual a verage

for trihalomethanes of >50µg/l

Company

Number of zones

operated by the

company in the region

Number of zones

exhibit ing an annual average

for trihalomethanes

>50µg/ l

Name of zones exhibit ing an annual average for

trihalomethanes >50µg/l

Br isto l W ater 52 0 (0) -


1 0 (0) -


10 0 (0) -

SSE W ater 2 0 (0) -

South W est Water 32 10 (12)

Burrows* Col lege* Dous land South Dr if t * Nor thcombe* Restormel W est* St i th ians* Tamar* Wendron* L it t lehemptson, Tot t i ford, and Bovey Cross*

Veol ia W ater Projects

1 0 (0) -

Wessex W ater 91 0 (0) -

Industry tota l 1,647 60 (37)

Notes : Zones marked * had an average of >50µg/ l t r iha lomethanes repor ted in Drink ing water 2011 . Numbers in brackets are the equivalent f i gures for 2011.

From Table 17, it can be seen that in 2012 there were ten zones in the

Western region (SWT) which contr ibuted to the total number of zones ( 60)

across the industry as a whole where the annual average value for THMs

exceeds 50µg/l. This ref lects a small improvement compared to the

situat ion in 2011 when there were 12 zones (SW T) with an average value

for THMs in excess of 50µg/l. South West Water have treatment

improvements planned for delivery in 2014, which should reduce THM

precursors at Wendron and Restormel works , however, based on this data

the Inspectorate wi l l be chal lenging whether the company has taken all the

appropr iate steps to minimise DBPs in al l of its zones. In November 2012,

the Inspectorate issued guidance to the industry on how the regulatory

requirements relat ing to DBPs should be appl ied in the context of Ofwat ’s

upcoming periodic review of prices (for the AMP6 period).

Western reg ion

35

Where companies in the region reported fai lures of the THM standard,

further details can be found in Chapter 4.2 – Chemical Quality –

Trihalomethanes sect ion.

Fluoride

Traces of f luoride occur naturally in many water sources, part icularly in

groundwaters. For example, naturally occurring f luoride is found in water

drawn from the great Oolite l imestone in the area of North East Somerset

and West Wiltshire (part icularly around Lacock). Consumers can obtain

specif ic information on the level of f luoride in the drinking water supply

to their home or workplace f rom their water company.

Fluoride is not removed by conventional water treatment. Water

f luoridat ion is carr ied out in a number of areas of England by the relevant

local water company at the request of the local statutori ly responsible

body, previously the Strategic Health Authorit ies (SHAs). As a

consequence of the reorganisation of the health service, a consultat ion

took place in 2012 about the transfer of responsibi l i ty for proposing new

f luoridat ion schemes and seeking the views of the publ ic on such schemes.

From 1 Apri l 2013 the current f luoridati on responsibi l i t ies of SHAs divided

into two parts.

Responsibi l i ty for publ ic consultat ion and decision -making on schemes,

and on funding the recurring costs of schemes, transfer red to unitary

and upper-t ier local author it ies (LAs).

Responsibi l i ty for making and managing f luoridat ion agreements and

contracts with water companies transfer red to Publ ic Health England

(PHE), an executive agency of the Department of Health, act ing as a

single national point of expert ise on behalf of LAs.

The central isat ion of al l f luoridation agreements and contracts with PHE

from Apri l 2013 offers an opportunity to review the local ly -determined

management arrangements inher ited f rom SHAs to identify best pract ice

and develop a consistent England-wide approach for the future.

The Drinking Water Inspectorate, as the national body charged with

monitor ing and regulat ing the qual ity of drinking water and advising

on technical standards, wi l l be support ing the Department of Health /PHE

in reviewing current arrangements and developing best pract ice for

the future.

The current Code of Practice on Technical Aspects of Fluor idation of

Water Suppl ies 2005 can be found at:

http:/ /www.dwi.gov.uk/stakeholders/guidance-and-codes-of-

pract ice/f luoridation-2005.pdf


36

There are no f luoridation schemes in the Western region. In 2012, al l

1,203 tests for f luoride taken across the region met the regulatory

standard (1.5mg/l).

Please refer to the DWI website (http:/ /www.dwi.gov.uk) for more

information on f luoridation.

Geosmin

Geosmin is a natural substance produced by the seasonal growth of algae,

in s low moving surface water . I t gives r ise to a character ist ic ‘earthy’ or

‘musty’ taste and odour discernible to consumers.

In Drinking water 2011 the Inspectorate reported the circumstances giving

r ise to nine posit ive earthy/musty taste and odour detect ions in consumer

tap samples col lected f rom the Porlock zone , near Minehead, operated by

Wessex Water. Changes in catchment management returning the moorland

to its natural state in Exmoor Nat ional Pa rk had necessitated a more

complex water supply management regime to address geosmin in the raw

water source (Nutscale reservoir ) at Por lock works. In 2012, there were a

further eight instances of taste and odour failures (March, April, August

and September). The Inspectorate put in place a Not ice preventing water

being supplied f rom Porlock works unti l effect ive control measures were in

place. Wessex Water is considering making longer term alterat ions to the

distr ibut ion network to enable abandonment of th is works.

Lead

The most common source of lead in tap water is pipework instal led before

the 1970s or the use of non-approved solder on cold water systems. Lead

may also leach f rom brass f it t ings.

The standard of 10µg/l comes into force at the end of 20 13; however, the

Inspectorate’s guidance on Regulat ion 30 makes it clear that companies

should already be act ing on the standard of 10µg/l. In part icular,

consumers should be notif ied and given appropr iate advice whenever the

standard of 10µg/l is exceeded. In 2012, companies in the region identif ied

ten failures of the standard of 10µg/l out of a total of 1,482 tests.

Western reg ion

37

Table 18: Number of tests >10µg/l lead 2010–2012

Company name 2010 2011 2012

Br isto l W ater 5 6 3


- - -


1 - -

South W est Water 1 1 4

SSE W ater - - -

Veol ia W ater Projects Ltd - - -

Wessex W ater 2 5 3 Note: These f igures a re no t reg iona l i sed and re fe r to the to ta l fo r each water company.

Table 18 shows the number of samples that exceeded 10µg/l at consumer

taps recorded by each company over the last three years. Most ( seven out

of nine) zones where these failures occurred receive phosphate dosing

which results in a protect ive layer bui lding up inside pipes minimising the

release of lead into tap water.

Two companies in the region, Wessex Water and South West Water, have

identif ied, in regulatory r isk assessments, the l ikel ihood of fail ing the

10µg/l lead standard and have put act ion plans in place. Wessex Water

offers its consumers f ree replacement of lead service pipes (the part of the

pipe owned by the consumer) and is working closely with LAs and housing

associat ions to ident ify propert ies where lead pipes can be replaced . One

such replacement occurred following a failure in Devizes zone in August.

South West Water has implemented enhanced monitor ing with pipework

identif icat ion to identify hot spot areas. The company is invest igating

mechanisms avai lable for discount ing the cost to customers to encourage

pipe replacement and is developing a lead awareness communications

campaign with LAs.

Lead above 10µg/l was not found in any sample f rom a publ ic bui lding

in the region.

As shown in F igure 19, the general s ituat ion regarding lead in the Western

region remains slight ly better than the industry overal l .


38

Figure 19: Percentage of tests meeting the future standard of 10µg/l

for lead between 2001 and 2012

94

95

96

97

98

99

100

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Perc

en

tag

e m

eeting

sta

ndar

d

Western Region

10ug/l Industry 10ug/l Regional

In November 2012, the Inspectorate issued guidance to the industry on

how the regulatory requirements relat ing to comp liance with the standard

for lead should be appl ied in the context of Ofwat ’s upcoming periodic

review of prices (for the AMP6 period).

Nickel

Nickel may be present in coatings on modern tap f it t ings. In 2012, a total

of 1,478 tests were carr ied out for nickel and all but two (1 SWT, 1 WSX)

met the standard (20µg/l).

A level of 36.4µg/l nickel was reported in a sample f rom a consumer’s tap

in Lit t lehempston/Tott iford zone in January and South West Water

demonstrated that the origin of the nickel was the tap f it t ing material .

By contrast, Wessex Water’s invest igation of a nickel failure in a sample

col lected f rom the Calstone zone (Calne) was crit ic ised by the

Inspectorate. The company has reviewed its procedures to ensure that

pref lush samples are not taken from taps that have been recently used

and f it t ings inspect ions wil l be included.

Nitrate and nitrite

Nitrate occurs natural ly in all source waters due to the decay of vegetable

material in soil. Nitrogenous fert i l isers used on arable farmland are a

signif icant source of nitrate in groundwater. Rainfall washes nitrate f rom

the soi l into lakes, r ivers and streams. Nitrate levels can be reduced by

Western reg ion

39

water treatment or by blending with another, low nitrate, water source . In

2012, al l tests for nitrate met the standard (50mg/l).

From extensive information gathered by the water companies, a l ikelihood

of drinking water suppl ies in the region fail ing the nitrate standard in the

longer term has been conf irmed at some sites. As a consequence, a legal ly

binding agreement is in place for catchment management together with the

construct ion of an integrated grid system to facil i tate blending, if required,

at several Wessex Water sites: Bulbridge, Chirton, Dunkerton, Fonthil l

Bishop, Hooke, Sturminster and Wylye which wil l benef it approximately

22,000 consumers. The catchment management measures are due to be

del ivered by 2015 with the grid system in place , if required, by March

2018. Similar ly, a blending scheme is to be progressed at Bristol Water’s

Frome works in Somerset by the end of September 2014. In November and

December monitoring had identif ied levels of nitrate at Fonthil l Bishop

works above 50µg/l, but blending with a source of lower nitrate water has

ensured compliance with the standard .

Nitr ite may be formed when chloramine is used as the residual dis infectant

to maintain the microbiological qual ity in the distr ibut ion network. The

formation of nitr ite is control led by careful opt imisation of the

chloramination process. Sembcorp Bournemouth Water pract ises

chloramination across its area of supply. Nitr ite can also form in samples

of water, af ter collect ion and before analysis, especial ly if the sample is

not kept cool.

In 2012, al l 4,725 tests carr ied out across the region for nitr ite met

the standard.

Pesticides and related products

This group of substances, generically cal led pesticides, includes many

organic chemicals ranging from weed kil lers, to insectic ides and

fungicides. Water sources may contain traces of pestic ide residues as

a result of agr icultural use (pest control on crops) and non -agricultural use

(herbicides for weed control on highways, railways etc.). Water companies

are required to assess the r isk to drinking water supplies of pestic ide use

in source water catchments and then test fo r those that might be present.

Companies have documented potential and actual pest ic ide hazards

through their Regulat ion 27 r isk assessments as informed by raw water

monitor ing. When pestic ides are f irst detected, water companies wi l l

enhance the monitor ing of raw water and notify the Environment Agency

to facil i tate appropriate act ion in the catchment to safeguard drinking

water qual ity.


40

In 2012, two tests in the region exceeded the standard for individual

pestic ides (0.1μg/l). Both cases were due to just one substance,

metaldehyde.

Metaldehyde

Metaldehyde is the act ive ingredient in some slug pel lets. In 2012, two

companies in the region reported a total of two failures (BRL 1, WSX 1),

which compares unfavourably to 2011, when there were no failures

reported in the Western region.

The two fai lures this year occurred at sites where the raw water source

has been ident if ied as being at potential r isk f rom metaldehyde. Since

2010, the Inspectorate has required companies to del iver legal ly binding

programmes of engagement with others to minimise the r isk to raw water

abstracted for drinking water f rom the usage of products containing

metaldehyde in ident if ied catchments. Companies are undertaking

modell ing work and extens ive monitor ing to ident ify the sources of

metaldehyde and potential act ions to address the r isks. Some companies

have recruited Catchment Management Off icers who regular ly meet with

farmers, manufacturers, agronomists, and off icers of Natural England and

the Environment Agency to share and promote good pract ice.

Table 20 shows that 48 out of a total of 348 abstract ion points in the

Western region are monitored for metaldehyde because they have been

identif ied as being potential ly at r isk. Table 20 also shows how, during

2012, monitor ing conf irmed there was an actual r isk at just ten (1 BRL,

3 SBW, 6 WSX) of these 48 abstract ion points.

Table 20: Abstraction points at risk of metaldehyde in 2012

Number of abstract ion points

Number of abstract ion points monitored for metaldehyde r isk

Number of abstract ion points where metaldehyde r isk ver i f ied by moni tor ing

Br isto l W ater 21 10 1

Cholder ton and Dis tr ic t W ater 2 0 0

Sembcorp Bournemouth W ater 17 12 3

South W est Water 60 0 0

SSE W ater* 0 0 0

Veol ia W ater Projects 3 3 0

W essex W ater 245 23 6

Region tota l 348 48 10

Industry tota l 2,358 687 110

Data are for abstract ion points in the region in 2012. Ver if icat ion of r isk is based on at least one sample conta in ing metaldehyde at a level above the standard. *SSE W ater do not operate abstract ion points in the region.

Western reg ion

41

One of the metaldehyde failures that occurred this year attracted publ ic

interest because of the act ion taken by the company. In January , Wessex

Water found a concentration of 0.138μg/l in a tap sample taken from a

property near Yetminster in the Sutton Bingham zone . Fol low-up

monitor ing conf irmed metaldehyde in the Sutton Bingham raw water

reservoir , whereupon Wessex Water drained the reservoir to approximately

30% in order to add fresh water to improve reservoir water qual ity. This

act ion attracted adverse publ ic ity due to the prevail ing drought and the

Inspectorate was cr it ical of the company for not writ ing prompt ly to

stakeholders to explain the situation . Companies are reminded that water

quality monitor ing, not just quantity considerat ions, should guide operating

strategies for the f i l l ing of raw water reservoirs over the winter period.

In January 2013, the Inspectorate issued guidance to the industry on how

the regulatory requirements relat ing to business plan proposals for the

control of pesticides, including metaldehyde, should be appl ied in the

context of Ofwat’s upcoming periodic review of prices (for the AMP6

period). See the Inspectorate’s website at

http:/ /www.dwi.gov.uk/stakeholders/ information- letters/2013/01-2013.pdf

for further information.

Radioactivity

Gross alpha/gross beta/ total indicative dose

Radioactivity in raw water can originate f rom natural substances or f rom

a specif ic point emission. Water companies are required to screen for

radionucl ides that emit either alpha or beta part ic les. I f such screening

exceeds guide values (Gross alpha 0.1Bq/l, Gross beta 1.0Bq/l) then fuller

analysis for specif ic radionucl ides is carr ied out to determine the o rigin.

Total indicat ive dose (TID) is a measure of the effect ive dose of radiat ion

through consumpt ion of the water. The guide value is 0. 1mSv/year.

In 2012, out of 910 tests in the Western region, there was just one

detect ion of gross alpha and no detect i ons of gross beta above screening

values (1 BRL).

The detect ion of gross alpha radioactivity in a sample in September ,

col lected f rom Clevedon works, in Somerset , was followed up by Bristol

Water and addit ional monitor ing demonstrated that this was a transient

occurrence that is not expected to recur .

The European Commission (EC) has proposed a new Direct ive on

radioact ive substances in dr inking water. The aim of the Direct ive,

commonly referred to as the Euratom Direct ive, is to implement

requirements for the monitor ing of drinking water supplies for radioact ive

substances which had not been specif ied in the 1998 Drinking Water


42

Direct ive. However, in England and Wales, monitor ing requirements for

radioact ive substances in dr inking water are set out in nat ional legislat ion.

Once the EC has agreed the f inal version of the Euratom Direct ive, which

is expected in mid-2013, it wi l l supersede the radioact ivity requirements of

the Drinking Water Direct ive and result in changes to nat ional legislat ion.

Tritium

Monitor ing for tr it ium is necessary only where a source of tr it ium is present

within the catchment and it cannot be shown through other survei l lance

programmes or investigations that the level of tr it ium is well below its

parametric indicator value of 100Bq /l.

A total of 640 tests for tr it ium were carr ied out in the Western region

in 2012 (138 BRL, 100 SBW, 382 SWT, 7 VWP, 12 WSX, 1 SSE). The

Inspectorate would have expected companies to proact ively identify the

l ikelihood of failure of this parameter and , where satisf ied that the water

supply is wel l below the specif icat ion , apply for a Notice to cease

unnecessary monitor ing.

Trihalomethanes

Trihalomethanes are DBPs and ar ise when chlorine is added to water

containing naturally occurring organic substance s. Water companies

minimise their production by opt imising treatment processes . The

regulat ions were amended in 2010 to require that THMs and other DBPs

be kept to a minimum while not compromising dis infect ion. This change

transposed into law a requirement of the 1998 European Drinking Water

Direct ive.

In 2012, out of 1,475 tests, only two exceeded the standard in the region.

(1 SWT, 1 WSX).

In July, a sample f rom a consumer’s tap in Sutton Bingham zone exhibited

a value of 100.4μg/l. On the previous day raw water quality had

deteriorated leading to Sutton Bingham works being taken out of supply.

This act ion was not suff icient , however, to prevent the formation of higher

than normal levels of THMs in the distr ibut ion network . The Inspectorate

has noted that Wessex Water’s operat ing regime at this site is not

optimised to minimise the production of DBPs and this wi l l be taken into

account during the Inspectorate’s forward programme of r isk-based

technical audit .

Also in July, a consumer’s tap sample f rom Sou th West Water’s Dr if t zone

(near Penzance) contained 121.5μg/l. At the t ime there were elevated

levels of organic precursors in the raw water at Drif t treatment works,

Western reg ion

43

probably due to the unseasonable wet weather. Demand from the works

was lower than usual for the same reason (for detai ls see the Drinking

water qual ity events sect ion and Annex 3 ). Drif t works also had a mean

value for THMs above 50μg/l fo r 2012, see the Disinfect ion by-products

sect ion for more detai ls.

Maintaining water quality in distribution

Elevated levels of iron or manganese are object ionable to consumers

because the water may appear turbid or discoloured due to unsightly

deposits and may also stain laundry and water f it t ings. Since 2004 , the

Inspectorate has been monitor ing the prog ress of companies’ distr ibut ion

maintenance work , using an index made up of three parameters (turbidity,

iron and manganese). Figure 21 shows the long-term improvements in the

Western region. In 2012, the index f igure for three companies in the region

improved (BRL, SBW, WSX), whereas the f igure for one company

deteriorated (SWT) compared to 2011.

Figure 21: Percentage of tests meeting the standards for turbidity,

iron and manganese

99.00

99.10

99.20

99.30

99.40

99.50

99.60

99.70

99.80

99.90

100.00

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Pe

rce

nta

ge

me

etin

g s

tan

da

rd

Western

Bristol Water Sembcorp Bournemouth Water

South West Water Wessex Water

Note: SSE W ater on ly began supp ly ing wate r in 2008 . They have ach ieved 10 0% in each yea r s ince. Veo l ia W ater Pro jec ts on l y began supp l y ing water to T idwor th i n 2009. They have ach ieved 100% in each year s ince. Cholde r ton and Dis t r i c t W ater have ach ieved 100% in each yea r exc ept 2002 (95 .83%), 2003 (97.62%) and 2004 (97.22%) .


44

Discolourat ion of tap water of ten prompts consumers to contact their water

company. The number of people contact ing water companies about

discoloured water is reported annual ly to the Inspectorate in accordance

with Information Letter 1/2006. Looking at the trend since 2008, it can be

seen from Figure 22 that across the industry the numbers of consumers

contact ing their water company to complain about discoloured water has

fallen f rom 70,643 to 50,456. In the Western region, the trend is equivalent

to the industry overall with the f igure now standing at 8,915 down from

16,790 in 2008. Overal l , the region accounts for 18% of all consumer

contacts for discolourat ion across England and Wales.

Figure 22: Total contacts for discolouration 2008–2012

-

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

2008 2009 2010 2011 2012

Western region

Rest of industry

Looking more closely at the region, mapping of the rate of consumer

contacts by zone shows the changing picture f rom 2007 to 2012. Rates of

consumer contacts about discoloured water in 2007 (Figure 23) i l lustrate

the situation before companies carr ied out AMP4 work. Figure 24 shows

the comparable rate at the end of 2012 af ter complet ion of AMP4 work.

These maps show the benef it to consumers in Devon and Cornwall of

South West Water’s long -term programme of distr ibut ion mains renovat ion.

The extent of improvement in the area around Honiton in east Devon is

less pronounced. The company exper ienced an increased level of

customer contacts during between January and March 2012, which

coincided with a programme of mains rehabil itat ion in the area. The

company are carrying out engineer ing works to reduce the amount of iron

that enters the distr ibut ion system from Greatwell treatment works.

Western reg ion

45

Figure 23: Map showing consumer contact rates per 1,000 population

for brown/black/orange water in 2007

Figure 24: Map showing consumer contact rates per 1,000 population

for brown/black/orange water in 2012


46

In 2012, across the whole of the region, out of a total of 4,398 tests there

were nine fai lures of relevant water quali ty standards at consumers’ taps:

iron (3 BRL, 1 SBW, 3 SWT) and manganese (2 SWT). There were no

failures for polycyclic aromatic hydrocarbons (PAH) or turbidity. These

failures did not have any geographical focus , but companies are expected

to have used the data to inform regulatory r isk assessments and DOMS.

In 2012, three iron fai lures recorded by Bristol Water were in zones where

the company is carrying out work to improve water qual ity in distr ibut ion.

A similar situation appl ies to the iron failure reported by Sembcorp

Bournemouth Water. One failure ident if ied a recurring problem at a

property in the Saltford Keynsham and Bitton zone (Br istol) that could not

be resolved by extensive f lushing and the company instal led a f i l ter on the

supply to the property in May 2013.

Annex 4 detai ls the legally binding programmes of distr ibut ion

maintenance work that is scheduled to be completed between now and

2015 to address ongoing distr ibut ion quality problems in the region.

Chapter 5: Drinking water quality events

Chapter 5:

Explains how events are classif ied.

Provides summary f igures of the number and type of events.

I l lustrates industry-wide learning points f rom case studies.

Water quality events are classif ied into f ive broad categories based on the

init ial company report. The categories are:

Not significant: no further information required by an inspector to assess

the event.

Minor: i t is unl ikely that further information would be required by an

inspector to assess the event .

Significant: a ful l company report is usual ly required to enable an

inspector to assess the event.

Serious: in addit ion to a full company report, the assessment may involve

more than one inspector in the investigat ion.

Western reg ion

47

Major: in addit ion to a full company report, wil l require an investigation led

by senior inspectors involving extensive information gathering and usual ly

site vis its.

In 2012, companies in the Western region notif ied the Inspectorate of

58 events. Table 25 shows how these events were classif ied.

Table 25: Water quality events in the region in 2012

Nature of event Risk assessment category (DWI)

Not signif icant

/minor Signif icant Major/serious

2011 2012 2011 2012 2011 2012

Air in water - - - - - -

Chemical 4 2 - 3 - -

Discoloured water 5 4 4 4 - -

Inadequate t reatment - - - - - -

Loss of suppl ies/poor pressure 5 6 2 1 - -

Microbiological 8 4 3 8 - -

Taste/Odour 6 7 2 2 - -

Health concern - - - 6 - -

Publ ic concern 7 8 - 2 - -

Other - - - 1 - -

Region overal l 35 31 11 27 - -

England and Wales 252 235 134 193 2 5

A summary of the nature, cause and durat ion of each event categorised

as signif icant, serious or major along with detai ls of the Inspectorate ’s

f indings are set out in Annex 3 . Most events were of relat ively short

durat ion and the company took appropriate act ion to inform and safeguard

consumers and other stakeholders. A comparison of 2011 events with

those of 2012 show a doubl ing in the numbers of signif icant, serious and

major events.

Wider learning points f rom event assessments in the region in 2012 are

highl ighted by the following case :

West Cornwall trihalomethane failure – South West Water

In early July, the standard for tr ihalomethanes was exceeded in a sample

col lected f rom a consumer ’s tap in one of South West Water’s zones

serving Penzance and the surrounding area in West Cornwall. The result

of 121.5µg/l was unusual and well above the standard of 100µ g/l. The area

suppl ies a populat ion of 17,000 and the supply includes f ive service

reservoirs. The source is water abstracted f rom Drif t impoundment

reservoir and treated at Drif t works. The cause of this part icular short - l ived

event was the company’s failure to proactively adjust the coagulant dose

to enable the treatment works to deal effect ively with a rainfall -related

change in organic qual ity of the raw water that was both predictable and

preventable. Although the Inspectorate was crit ical of this operational


48

fail ing, it is the wider context and ensuing consequential decisions and

act ions by the company that the Inspectorate f inds part icular ly

disappoint ing.

The need for improvements at Drif t works to deal with organics in the raw

water had been long recognised by the company and addit ional treatment

(GAC and UV/peroxide) had been instal led; however, at the t ime of the

event there were unresolved commissioning problems (chlor ine control).

Notwithstanding the situat ion, the event prompted the company to bring

the new GAC process into use at end of July, and in doing so, they

overlooked the need to make essential adjustments to the operating

criteria for the exist ing chlor inat ion process . Therefore, higher than normal

residual chlor ine levels were exper ienced by consumers. Not having been

forewarned of the planned changes to their water supply , unsurpris ingly

consumers began to complain about the change in taste and odour. By

October these circumstances had led the company to feel compelled to

wr ite to around 13,500 consumers to give a retrospect ive explanation and

apologise.

The Inspectorate was part icular ly disappointed about the aforementioned

circumstances. for two reasons. First ly , i t is known that consumers are

sensit ive to changes in water qual ity and wil l report a concern unless they

have been given advance information about planned changes. Companies

are reminded of the published benef its of giving consumers advance

wr it ten information about planned changes to water supply arrangements.

Secondly, the situation exemplif ies how a lack of co-ordinat ion in the way

water companies del iver asset improvements and manage operations has

implicat ions for compliance with Regulat ion 26. Among other things, this

regulat ion requires companies to design, operate and maintain the

dis infect ion process so that DBPs are kept as low as possible without

compromising the ef fect iveness of disinfect ion. Senior management in

companies would be well advised to take steps to s at isfy themselves that

they have reviewed and put in place the ‘hol ist ic design, bui ld, operate ’

process implic it in Regulat ion 26.

The Inspectorate view of the event was that the THM exceedance was

avoidable, although the Inspectorate recognised the actual exceedance

was isolated to a single sample. The concentrat ion of THMs in the

regulatory sample was 121.5µg/l ( the prescribed concentrat ion value is

100µg/l). Regulat ion 26(1A) requires companies to design, operate and

maintain the dis infect ion process so that DBPs are kept as low as possible

without compromising the effect iveness of disinfect ion. I t was considered

the company had taken posit ive act ion since the t ime of the event to

ensure compliance with Regulat ion 26.

No of fences are currently under considerat ion by the Inspectorate in

connection with any of the events that occurred in the region in 2012.

Western reg ion

49

Chapter 6: Technical audit activity

Chapter 6:

Descr ibes the audit strategy of the Inspectorate.

Summarises the audits carr ied out in 2012 in terms o f the

Inspectorate’s main f indings.

Reports on consumer complain t numbers.

I l lustrates industry-wide learning points f rom case studies.

The Inspectorate has operated a r isk -based approach to technical audit

since 2005 and no technical audit takes place without a reason.

During 2012, Parl iament gave the Chief Inspector the power to recover

the costs of regulat ing the water industry and the charging scheme was

introduced in Apri l 2013. Technical audit is the main act ivity included in

the variable element of the charging regime. Detai ls of the charging regime

can be found in the Inspectorate’s Information Letter 03/2013: Cost

recovery – publicat ion of fees and the associated schedule avai lable at

http:/ /www.dwi.gov.uk/stakeholders/ information - letters/ index.htm

Figure 26 i l lustrates the audit act ivity in the region between 2005

and 2012.


50

Figure 26: Audit activity in the region 2005–2012*

*Exc ludes work on schemes and r isk assessments l is ted in Table 28

0

5

10

15

20

25

30

35

2005 2006 2007 2008 2009 2010 2011 2012

Nu

mb

er o

f a

ud

its

Abstraction and treatment

Service reservoir integrity and management

Distribution operational maintenance

Sampling and analysis

Response to recommendations

Other

Consumer complaint handling

Table 27 sets out all the r isk -based technical audits, which took place

in Western region during 2012 together with summary f indings. This is

followed by information about industry -wide themes assessed during

the year and the part iculars of consumer complaint investigations by

inspectors including a case study.

Table 27: Summary of the technical findings from operational audits

in the region in 2012

Company Location and reason

Main f indings from audit

Audit focus: Abstract ion and treatment


Alderney works – improvement works

Unsat isfac tory

Recommendations made regarding:

Accuracy and unders tanding of contact t ime (Ct) ca lculat ions.

Clar i f icat ion of exact works needed to repair leak ing f i l ters.

Ver if icat ion that a l l the issues ident i f ied by internal inspect ion of t reated water reservoirs are complete.

Western reg ion

51



Audit focus: service reservoir integrity and management

Br isto l W ater Frome service reservoirs – sampl ing faci l i t ies

General ly sat isfac tory Recommendations made regarding:

Removal of tree sapl ing growing out of reservoir bank.

Fai lure to address lack of sample taps avai labi l i t y at service reservoirs and consequent ia l cont inuat ion of poor pract ice (sampl ing at proper t ies downstream).


Chase service reservoir – sampl ing faci l i t ies

General ly sat isfac tory

Recommendation made regarding:

No schemat ics on s i te and labels less than clear .


Hightown service reservoir – sampl ing faci l i t ies


Recommendation made regarding:

Spiders web around sample tap, poor hygiene and suggests inadequate tap c leaning pr ior to sampl ing .

Wessex Water

Charmy Down Tower – sampl ing faci l i t ies



Sample point re located but not label led.

Wessex Water

Hol l ies Lane service reservoirs – sample fac i l i t ies



Tree growth around per imeter of reservoir and shrub growth overhanging access hatches, both potent ia l ly af fect ing integr i ty.

Wessex Water

Hampton Down service reservoirs – sample fac i l i t ies

Unsat isfac tory


Concern about absence of membrane on service reservoirs despite previous internal inspect ion indicat ing the need.

Poor s ite condi t ion.

Poor sample point label l ing.

Wessex Water

Pr imrose Hi l l serv ice reservoir – m icrobio logical r isk

Unsat isfac tory


Lack of s i te maintenance, overgrown and fai lure to adhere to complete tasks as ass igned on worksheet.

Poor sample point label l ing.

Evident s igns of animal burrows on reservoir roof .


52



Audit focus: Sampling arrangements


Samplers Unsat isfac tory


Lack of necessary deta i l in sampl ing procedures manual .

No company audits of samplers carr ied out.

Out of date analyt ica l qual i t y contro l (AQC) standards.

Dis infect ion method for sample taps in d irec t conf l ic t wi th best pract ice and SCA method.

Lack of evidence of adequate tra in ing and ref resher t ra in ing for samplers.

Lack of evidence that publ ic bui ld ings are included in random programme (no samples in 2011).

Van f r idge temperatures not recorded, inappropr iate f r idge in use at sample col lec t ion point.

Frequency of sampl ing programme sat isfac tory.

Audit focus: Analysis


Analys is – turb id i ty



Fai lure to agree not i f icat ion cr i ter ia wi th SEW laboratory resul t ing in fa i lure to analyse s tored sample as par t of invest igat ion.

Analyt ica l method sat isfactory and or ig inal resul t va l id .

Wessex Water

Sampl ing f requency

Unsat isfac tory


Records of reservoirs out of supply incorrect.

Inaccurate gr id references for several reservoirs .

Audit focus: Consumer complaint handling

Br isto l W ater Discolourat ion (1)

Sat isfac tory

South W est Water

I l lness (1)

Other (1)

Sat isfac tory

During 2012, the Inspectorate carr ied out a series of themed audits

focusing on the duty of companies to ensure that the samples they col lect

are representat ive of the water supply. Audits must be r isk based and the

evidence support ing this audit act ivity was the relat ively high number of

company compliance assessment reports where a fai lure had been

attr ibuted to the unrepresentat ive nature of the sample facil i t ies at service

reservoirs and works. A to tal of 30 sites (27 service reservoirs, 3 works) ,

Western reg ion

53

operated by six companies , were selected according to r isk combined with

a random element making the f indings and conclusions appl icable to the

industry as a whole. During these visits inspectors assessed t he location

and design of sampling points, hatch cover secur ity, general site

maintenance, and sample schedul ing data and frequency. In total , these

audit reports contained in excess of 30 recommendat ions about actual or

potent ial observed contravent ions o f regulatory duties. Around half of the

audits were general ly sat isfactory (15) or sat isfactory (1) , however,

recommendat ions were made in relat ion to al l s ites and 14 were assessed

as unsat isfactory.

The type of problems observed were as fol lows: absence of sample point

label l ing; taps in rust ing old cabinets in exposed condit ions and, in one

case, drain water appeared to f low back into the body of the reservoir; a

lack of shrub and tree clearing on the roof of the cel ls (a r isk to reservoir

integrity); instal lat ion of secure alarmed hatches where the commissioning

procedures omitted alarm relays back to a control centre and staff training;

evidence that reservoir turnover strategies were not followed because

checks prior it ised maintaining reservoir levels over managing turnover;

sample taps known to be inoperable in cold weather such that it was

routine pract ice for substitute samples to be collected f rom downstream

consumer premises.

Sampling f requency checks were general ly sat isfactory although

companies were not always providing ‘out of supply’ data and on two

occasions the ‘out of supply’ information provided was incorrect.

The Inspectorate was disappointed to note the low pr iority given by several

companies to the replacement of sample points ident if ie d as being

defect ive. In some instances, remedial work had been outstanding for a

number of years during which t ime the company had cont inued to use the

defect ive sample point for regulatory compliance purposes. Overal l , the

Inspectorate considers that the industry’s approach to maintenance of

sampling facil i t ies and site management is s lack and needs improvement

through senior management attention and targeted performance

monitor ing.

Addit ional ly, Table 28 summarises the Inspectorate’s act ivity in relat ion to

enforcing improvements to water qual ity. These act ivit ies cover the putt ing

in place of Notices or undertakings and the checks made to ensure the

work specif ied by the company is technical ly appropr iate , has been carr ied

out in the required t imescales and the benef its to water qual ity have been

real ised.


54

Table 28: Summary of the Inspectorate’s work in 2012 in relation to

enforcing water quality improvements

Activity Number of improvement programmes (and outcomes)

Issuing of

statutory

instruments

Undertakings:

SWT (2)

Notices:

WSX (1), BRL (1)

Reviewing

schemes

Schemes reviewed:

SWT (17), BRL (24), WSX (31), CHO (2), SBW (5)

Changes of

solut ion

Schemes examined:

BRL (1)

Closure of

schemes

Schemes reviewed for closure:

Satisfactory – scheme closed

SWT(1), WSX (3)

Inspect ion of

schemes

WSX (1) – sat isfactory

Friar Whaddon works

BRL (2) – sat isfactory

Washout instal lat ion and mains f lushing

Trunk mains cleaning

Receipt and

review of r isk

assessments

BRL (4) WSX (1)

Consumer complaints to the Inspectorate

The number of consumers in the Western region who had cause to

complain to the Inspectorate because the company failed to resolve a

water qual ity concern was three, the same as 2011. Figure 26 shows how

consumer complaints to the Inspectorate have fallen overal l s ince 2005.

Out of the total of 104,565 consumer contacts to water companies in

England and Wales, 15% were to companies in this region. This ref lects

Western reg ion

55

the general ly poor state of distr ibut ion management and maintenance

in the region.

Rates of consumer contacts to each water company in the region and

numbers of complaints received by DWI are detai led in Table 29.

Table 29: Complaint rates to industry and to the Inspectorate

Company Rate of consumer contacts per 1,000 people

1 to water

companies in 2012

Number of complaints received by DWI in 2012

Br isto l W ater 2.2 1


- -


1.3 -

South W est Water

5.6 2

SSE W ater 0.8 -


0.6 -

Wessex W ater 2.5 -

Industry rate 1.9 49

1Rate o f contac ts for appearance, tas te and odour and i l lness

During 2012, the fol lowing complaint case i l lustrates why the Inspectorate

considers it important that companies have in place ef fect ive arrangements

for diagnosing and responding to consumer contacts.

Case study

Dispute resolution

The Inspectorate was contacted in December by a consumer l iving

in North Devon who was concerned about an ongoing complaint being

investigated by South West Water. The consumer reported a skin al lerg y,

irr itat ion on his wife’s hand and the i l lness of a dog, all of which the

consumer associated with the water supply. The company had had

previous contacts with this consumer for a variety of reasons , but on

this occasion he addit ional ly contacted both t he Inspectorate and the

Consumer Council for Water. The company had already init iated an

investigation including sampling, a f it t ings inspect ion, and advice f rom

a company scientist , and in January 2013 the company replaced the


56

communication pipe and meter. Although sampling and the f it t ings

inspect ion carr ied out in November did not f ind anything to explain the

problems reported by the consumer, it did determine that the consumer

had carr ied out extensive plumbing at the property and had in place a

rainwater harvest ing system which was being used for the washing

machine and toi let f lushing. I t also came to l ight that the consumer had

been exper iment ing in some indeterminate capacity with hydrogen

peroxide. Unqual if ied handl ing of this chemical by the consu mer may well

have given r ise to the reported skin problems , however, other complicat ing

factors were also pert inent. Just pr ior to making his complaint to the

company, the consumer had received a f inal bi l l payment demand. The

company suspended the debt recovery process while invest igating the

water qual ity complaint , but af ter obtaining the consumer’s agreement that

water qual ity was satisfactory (being drunk happi ly by the dog !) they

recommenced debt recovery. Four days later the consumer made a further

water qual ity complaint to the company and a day later to the Inspectorate.

When in February 2013 the inspector closed the case, concluding that the

company had dealt with the matter sat isfactori ly, the consumer threatened

to lodge a complaint about the investigating inspector.

This case serves to i l lustrate for companies the nature of much of the

Inspectorate’s consumer water qual ity complaints handl ing work. While

relat ively few in number, many of these cases ar ise when a consumer

resorts to making allegat ions about water quality as a way of attract ing or

divert ing attention, to or away from, some other dispute or grievance they

have with the company. In this case, two of the most common reasons for

such behaviour were in play: debt recovery for non -payment of a water bi l l

and exercise of the company’s water f it t ings inspect ion and enforcement

powers. While inspectors wi l l mediate to secure a way forward by

impart ing independent knowledge about water qual ity and regulat ion, water

companies must recognise these situat ions quickly and take steps to

appoint a case of f icer, thereby avoiding inspectors being put in the

posit ion of becoming arbiters of f inancial or other types of customer

disputes. I t is a regrettable fact that when a water company does not

pract ice effect ive dispute resolut ion, these cases become vexatious

against the Inspectorate, of ten involving MPs and ministers, and result ing

in Inspectorate staf f receiving unpleasant correspondence and cal ls which

quite of ten persist for years.

For further information on the Water Supply (Water Qual ity) Regulat ions

2000, or the microbiological and chemical parameters covered by the

regulat ions please refer to the DWI website (http:/ /www.dwi.gov.uk) .

I f you have a need for more specif ic information than that o n our website,

please contact us on the DWI enquiry l ine: 0300 068 6400.

Western reg ion

57

Annex 1 Further sources of information

The publ icat ion Drinking water 2012 comprises the regional reports for

England and a report covering Wales. There are four regional reports fo r

England (Central and Eastern, London and South East, Northern, and

Western) and one for Wales ( in two languages). Each report presents

information f rom 2012 under the following headings:

Overview of drinking water qual ity in the region.

Water supply arrangements.

Drinking water qual ity test ing.

Drinking water qual ity results.

Technical audit act iv ity.

Drinking water qual ity events.

There are also separate reports covering private water supplies, one

cover ing England and one covering Wales.

The reports and other content are publ ished on the DWI website

(http:/ /www.dwi.gov.uk).

Content of the CD

The CD suppl ied with the printed report holds all of the above content and

addit ional ly it contains:

Water company look-up tables

These summarise al l the results of water company monitor ing in 2012.

They provide information on:

what was tested;

how many tests were performed;

the range of the results of test ing; and

how many tests failed to meet the standards.

Significant drinking water quality events in England and

Wales 2012

To promote shared learning, the Inspectorate has compiled a l ist of al l

events that occurred in 2012 which i l lustrate the nature and cause of each

event, the main act ions by the company and f indings f rom the inspectors’

assessments. Relevant content f rom this overal l l ist is contained in an

annex to each regional report.


58

Annex 2 Glossary and description of standards

These def init ions wil l assist the understanding of the report where

technical terms have been used.

µg/l microgram per l i t re (one mil l ionth of a gram per l i t re) .

1,2-Dichloroethane is a solvent that may be found in groundwater in the v ic in ity of industr ia l s i tes . W here necessary i t can be removed by spec ia l water treatment . A European health-based standard of 3μg/ l appl ies.

Acrylamide European heal th-based s tandard. A monomer is not normal ly found in dr ink ing water. I t is produced in the manufacture of polyacrylamides occas ional ly used in water treatment . I ts presence in dr ink ing water is l im ited by control of the product spec if icat ion. Standard is 0.1µg/ l .

Aesthetic assoc iated wi th the senses of taste, smel l and s ight .

Aggressive

a term used to indicate that the water has a tendency to d issolve copper (and other metals) f rom the inner surface of a p ipe or water f i t t ing such as a tap.

Alkali

a solut ion conta in ing an excess of f ree hydroxyl ions, wi th a pH greater than seven.

Aluminium occurs natura l ly in some source waters . I t is removed f rom dr ink ing water by convent ional water t reatment (coagulat ion and f i l t ra t ion) . Aluminium sulphate and polyaluminium chlor ide may be used as water treatment chemicals at some water treatment works. A nat ional standard of 200μg/ l appl ies.

Ammonium salts are natura l ly present in trace amounts in most waters. Their presence might indicate contaminat ion of sanitary s ignif icance and they interfere wi th the operat ion of the dis infect ion process. An indicator parameter wi th a guide value of 0.5mg/ l.

Western reg ion

59

Analytical qual ity control (AQC)

the method used to ensure that laboratory analys is methods are performing correct ly.

Antimony is rare ly found in dr ink ing water . Trace amounts can be der ived f rom brass tap f i t t ings and solders. A European heal th -based standard of 5μg/ l appl ies.

Aquifer water -conta ining underground s trata.

Arsenic occurs natura l ly in only a few sources of groundwater. Spec if ic water t reatment is required to remove i t . A European health -based s tandard of 10μg/l appl ies .

Benzene is present in petro l. I t is not found in dr ink ing water , but i t can migrate through underground p last ic water p ipes i f petro l is spi l t in the v ic in ity. A European health-based standard of 1μg/ l appl ies . Some bott led waters and sof t dr inks which inc lude sodium benzoate as an ingredient have been reported as conta ining benzene.

Benzo(a)pyrene is one of several compounds known as polycyc l ic aromat ic hydrocarbons (PAHs) . Their source in dr ink ing water is as a resul t of deter iorat ion of coal tar , which many years ago was used to l ine water pipes. Due to extens ive water mains refurb ishment and renewal i t is now rare to detect th is substance in dr ink ing water. A European health-based standard of 0.01μg/ l appl ies.

Boron in surface water sources comes f rom industr ia l d ischarges or f rom detergents in treated sewage ef f luents . The very low concentrat ions found in some dr ink ing waters are not a concern to publ ic heal th. A European heal th -based standard of 1mg/ l appl ies .

Bromate can be formed dur ing d is infect ion of dr ink ing water through a react ion between natura l ly occurr ing bromide and strong ox idants (usual ly ozone). I t may be generated in the manufacture of sodium hypochlor i te d is infectant . Except ional ly, groundwater can be contaminated wi th bromate, re leased f rom an industr ial s i te. A European health-based standard of 10μg/ l appl ies.

Bulk supply water suppl ied in bulk , usual ly in treated form, f rom one water company to another.


60

Cadmium is rare ly detected in dr ink ing water and trace amounts are usual ly due to d issolut ion of impur it ies f rom plumbing f i t t ings. A Europea n health-based s tandard of 5μg/ l appl ies .

Catchment

when used in connect ion wi th water , the catchment is the area dra ined by a r iver or water body.

Chloramination the process of generat ing a chloramine d is infectant res idual in water leaving a treatment works.

Chloramine a substance formed by a react ion between chlor ine and ammonia, used as a d is infectant in d istr ibut ion systems because of i ts long - las t ing propert ies compared to chlor ine.

Chloride is a component of common sal t . I t may occur in water natura l ly, but i t may also be present due to local use of de- ic ing salt or sal ine intrus ion. An indicator parameter with a guide value of 250mg/l .

Chlorine residual the small amount of ch lor ine or chloramines present in dr ink ing water to maintain i ts qual i t y as i t passes through the water company’s network of p ipes and household p lumbing.

Chromium is not present in dr ink ing water . A European health-based s tandard of 50μg/ l appl ies.

Clostridium perfringens is a spore-forming bacter ium that is present in the gut of warm-blooded animals . The spores can survive d is infect ion. The presence of spores in dr ink ing water indicates h is tor ic contaminat ion that requires invest igat ion. The standard is 0 per 100ml.

Coagulat ion a process employed dur ing dr ink ing water treatment to ass ist wi th the removal of par t icu late matter.

Coliform bacteria

are widely d istr ibuted in the environment of ten as a result of human or animal ac t ivi ty, but some grow on p lant mat ter . Their presence in a water supply indicates a need to invest igate the integr i ty of the water supply system. The s tandard is 0 per 100ml.

Western reg ion

61

Colony counts are general techniques for detect ing a wide range of bacter ia, the types and numbers being dependent on the condit ions of the test . These counts , i f done regular ly, can help to inform water management, but they have no direct heal th s ignif icance. The s tandard is ‘no abnormal change’.

Colour occurs natura l ly in upland water sources. I t is removed by convent ional water treatment. A nat ional standard of 20mg/ l on the Plat inum/Cobalt (Pt /Co) scale appl ies .

Communicat ion pipe the connect ion f rom the water main to the consumer’s property boundary.

Compliance assessment a compar ison made by the Inspectorate of data gathered by water companies against standards and other regulatory requirements .

Compound a compound cons ists of two or more e lements in chemical combinat ion.

Concessionary supplies histor ica l f ree suppl ies of water for a householder , es tabl ished when a company wanted to lay mains across land and the landowner might agree, subject to a permiss ion, to take a supply of water f rom the main.

Conduct ivity is a non-spec if ic measure of the amount of natura l d issolved inorganic substances in source waters . An indicator parameter wi th a guide value of 2,500µS/cm.

Contact tank a tank, normal ly s i tuated on a treatment works s ite, which forms par t of the d is infect ion process. A d is infectant chemical (normal ly chlor ine) is dosed into the water as i t f lows into the tank. The per iod of t ime that the water takes to f low through the tank a l lows suf f ic ient ‘contact ’ t ime for the chemical to k i l l , or deact ivate, any v iruses or pathogenic organisms that may be present in the water.

Copper in dr ink ing water comes mostly f rom copper p ipes and f i t t ings in households. In general, water sources are not aggress ive towards copper, but problems very occasional ly occur on new hous ing estates. These ‘b lue water ’ events can be avoided by good p lumbing pract ices. A European health-based standard of 2mg/l appl ies .


62

Cryptosporidium is a paras ite that causes severe gastroenter i t is and can survive d is infect ion. In the UK, cont inuous monitor ing is under taken at works c lassif ied by the company as being at s ignif icant r isk .

Cyanide is not present in dr ink ing wa ter . A European health-based s tandard of 50μg/ l appl ies.

Dead leg refers to a p iece of p ip ing which is stopped of f at one end, but is connected to the supply at the other end and can result in stagnant water in the p ipework.

Distribution systems a water company’s network of mains, p ipes, pumping stat ions and service reservoirs through which treated water is conveyed to consumers.

Drinking water standards the prescr ibed concentrat ions or values l is ted in regulat ions.

EC Drinking Water Direct ive Counci l Direct ive 98/83/EC December 1998 – set t ing out dr ink ing water standards to be appl ied in member states.

Enforcement act ion the means, as set out in the W ater Act 1989 and consol idated into the W ater Industry Act 1991, by which the Secretary of State requires a water company to comply w i th certa in regulatory requirements.

Enterococci see Escher ichia col i .

Environment Agency the Environment Agency is respons ib le for mainta in ing or improving the qual i t y of f resh, marine, surface and underground water in England and W ales.

Epichlorohydrin can be found in trace amounts in polyamine water t reatment chemicals. I ts presence in dr ink ing water is l im ited by contro l of the product spec if icat ion. A European heal th -based standard of 0.1μg/ l appl ies.

Epidemiology a process of s tudying the d istr ibut ion of cases of d isease wi thin a populat ion in re lat ion to exposure to poss ible sources of the infect ion, wi th a v iew to establ ish ing the actual source of the infect ion.

Western reg ion

63

Escherichia col i and Enterococci

are bacter ia present in the gut of warm -blooded animals. They should not be present in dr ink ing water and, i f present , immediate act ion is required to ident i fy and remove any source of faecal contaminat ion that is found. The standard is 0 per 100ml.

Event

water companies have to inform the Inspectorate about occas ions when water qual i t y or suf f ic iency is af fected or when publ ic conf idence in dr ink ing water qual i ty may be impacted. The Inspectorate refer to these ins tances as ‘Events ’ .

Filt ration the separat ion of suspended par t icu late matter f rom a f lu id.

Fluoride occurs natura l ly in many water sources, espec ial ly groundwater. I t cannot be removed by convent ional water treatment so h igh levels must be reduced by b lending wi th another low f luor ide water source. Some water companies are required by the local heal th author i ty to f luor idate water supplies as a protect ion against tooth decay. The dr ink ing water standard ensures levels are safe in e ither c ircumstance. Fluor idat ion of water is a Depar tment of Health pol icy. A European health-based s tandard of 1.5mg/ l appl ies.

Geosmin a substance produced by the growth of a lgae, normal ly in surface waters which g ives r ise to a character is t ic ‘ear thy’ or ‘musty’ taste or odour.

Granular activated carbon an adsorbent f i l t ra t ion media used to remove trace organic compounds f rom water .

Gross alpha/gross beta

radioact iv i ty in raw water can or ig inate f rom natura l substances or f rom a spec if ic point emission. W ater companies are required to screen for radionuc l ides that emit e ither a lpha or beta par t ic les . I f such screening exceeds guide values (gross a lpha 0.1Bq/ l , gross beta 1.0Bq/ l) then fu l ler analys is for spec if ic radionuc l ides is carr ied out to determine the or igin.

Groundwater water f rom aquifers or other underground sources.


64

Hydrogen Ion

(pH)

gives an indicat ion of the degree of ac id i ty of the water . A pH of 7 is neutra l; va lues below 7 are ac id ic and values above 7 are a lkal ine. A low pH water may result in p ipe corros ion. This is corrected by adding an alkal i dur ing water t reatment. A specif icat ion of between 6.5 and 9.5 appl ies.

Improvement programmes water company improvement works, these are legal ly b inding on the company and each programme wi l l remedy an actual or pote nt ia l breach of a dr ink ing water s tandard wi th in a spec if ied t ime per iod.

Indicator organism an organism which indicates the presence of contaminat ion and hence the poss ib le presence of pathogens.

Indicator parameter something that is measured to check that control measures, such as water treatment , are work ing ef fect ive ly.

Information Letter formal guidance to water companies g iven by the Inspectorate and publ ished on the Inspectorate ’s webs ite at ht tp:/ /www.dwi.gov.uk

Inspectorate The Dr ink ing W ater Inspectorate.

Iron is present natura l ly in many water sources. I t is removed by water treatment. Some iron compounds are used as water treatment chemicals. However, the commonest source of iron in dr ink ing water is corros ion of iron water mains. A nat ional s tandard of 200μg/l appl ies .

Lead very occasional ly occurs natura l ly in raw waters, but the usual reason for i ts presence in dr ink ing water is p lumbing in o lder propert ies. I f the water supply has a tendency to d issolve lead then water companies treat the water to reduce consumer exposure. The permanent remedy is for householders to remove lead p ipes and f i t t ings. A European heal th -based standard of 25μg/ l appl ies, but 10μg/l wi l l apply f rom 25 December 2013 onwards.

m3/d cubic metre per day.

Manganese is present natura l ly in many sources and is usual ly removed dur ing treatment . A nat ional standard of 50μg/ l appl ies .

Western reg ion

65

Mean zonal compliance percentage

a measure of compl iance wi th dr ink ing water standards introduced by the Inspectorate in 2004.

Mercury is not found in sources of dr ink ing water. A European health-based standard of 1μg/ l appl ies.

Methyl- isoborneol (MIB) a natura l substance produced by the growth of a lgae, normal ly in surface waters which g ives r ise to a character is t ic ‘earthy’ or ‘musty’ tas te or odour. I t is detected by the method for assessing tas te and odour .

mg/l mil l igram per l i t re (one thousandth of a gram per l i t re) .

Microbiological assoc iated wi th the study of microbes.

Ml/d megal i tre per day (one Ml/d is equivalent to 1,000 m

3/d , 1 mi l l ion l i t res /d or to 220,000

gal lons/d).

Nickel occurs natura l ly in some groundwater and where necessary spec ia l treatment can be insta l led to remove i t . Another source of nickel in dr ink ing water is the coat ings on modern taps and other p lumbing f i t t ings. A European health -based standard of 20μg/ l appl ies .

Nitrate occurs natura l ly in a l l source waters a l though h igher concentrat ions tend to occur where fert i l isers are used on the land. Nitrate can be removed by ion exchange water treatment or through b lending wi th other low ni trate sources. A European health-based standard of 50mg/ l appl ies .

Nitrite is somet imes produced as a by-product when chloramine is used as the essent ia l residual d is infectant in a publ ic water supply. Chloramine is the res idual d is infectant of choice in large d is tr ibut ions systems because i t is more stable and long- last ing. Carefu l operat ion of the d is infect ion process ensures levels of ni tr i te are kept below the standard. A European health -based s tandard of 0.5mg/l appl ies.

Notice

an ins truct ion served by the Secretary of State ( in the case of water suppl ies , the Chief Inspector of W ater) requir ing spec if ic act ions to be taken by the rec ip ient wi th in a spec if ied t imescale.


66

Odour can ar ise as a consequence of natura l processes in surface waters, par t icular ly between late spr ing and ear ly autumn. W ater treatment with act ivated carbon or ozone wi l l remove natura l substances caus ing taste. The s tandard relates to the evaluat ions of a panel of people assessing samples in the laboratory.

Ofwat the water industry’s economic regulator .

Oocyst the res istant form in which Cryptospor id ium occurs in the environment, and which is capable of caus ing infect ion.

Organoleptic character is t ics of a substance as detected by our senses, for example taste, odour or colour.

Ozone process (ozonation) the appl icat ion of ozone gas in dr ink ing water t reatment.

Parameters the substances, organisms and propert ies l is ted in Schedule 2 and Regulat ion 3 of the regulat ions. Parameter def in it ions can be found in th is annex.

Pathogen an organism which can infect humans and cause d isease.

PCV see ‘Prescr ibed concentrat ion or value’ .

Periodic review the economic regulator ’s process of sett ing water pr ices.

Pest icides any fungic ide, herbic ide, insect ic ide or re lated product (excluding medic ines) used for the control of pests or d iseases.

Pest icides – organochlorine compounds (aldrin, dieldrin, heptachlor, heptachlor epoxide)

are no longer used in the UK because they are pers is tent in the environment. They are not found in dr ink ing water . A European chemical standard of 0.03μg/ l for each compound applies .

Western reg ion

67

Pest icides – other than organochlorine compounds

is a d iverse and large group of organic compounds used as weed k i l lers, insect ic ides and fungic ides. Many water sources conta in traces of one or more pest ic ides as a resul t of both agr icu ltura l and non-agr icu l tura l uses, main ly on crops and for weed contro l on h ighways and in gardens. Where needed, wate r companies have insta l led water treatment (act ivated carbon and ozone) so that pest ic ides are not found in dr ink ing water . W ater companies must test for those pest ic ides used widely in their area of supply. Pest ic ide monitor ing thus var ies according to r isk . A European chemical standard of 0.1μg/l for each indiv idual substance and 0.5μg/ l for the tota l of a l l pest ic ides appl ies .

Phosphate dosing t reatment of water that resul ts in a protect ive f i lm bui ld ing up on the ins ide of p ipes minimising the l ike l ihood of lead being present in dr ink ing water suppl ied through lead p ipes.

Plumbosolvency the tendency for lead to d issolve in water.

Polycyclic aromatic hydrocarbons

(PAHs)

is a group name for several substances present in petroleum-based products such as coal tar . (see Benzo(a)pyrene l is ted above for more informat ion) . A European health -based standard of 0.1μg/l for the sum of a l l the substances appl ies.

Powdered activated carbon (PAC)

powdered act ivated carbon is employed in treatment processes to remove pol lu tants.

Pre- and post-renovation assessment (PPRA)

a programme of assessment before and af ter mains renovat ion to demonstrate jus t i f icat ion for the work , and the improvements achieved by the renovat ion.

Prescribed concentration or value (PCV)

the numerical va lue assigned to dr ink ing water standards def in ing the maximal or min imal legal concentrat ion or value of a parameter .

Private supplies water suppl ied for human consumption or food product ion which is not provided by a water undertaker or l icensed water suppl ier .

Protozoan parasites a s ingle cel l organism that can only survive by infect ing a host .

Public suppl ies water suppl ied by a company l icensed for that purpose.


68

Raw water water pr ior to receiv ing treatment for the purpose of dr ink ing.

Regulations The W ater Supply (W ater Qual i t y) Regulat ions 2000 (England), 2010 (W ales).

Remedial act ion act ion taken to improve a s i tuat ion.

Remote operated vehicle (ROV)

equipment for inspect ing areas that are d if f icu lt to access, for example, tanks and pipes.

Residual disinfectant the small amount of ch lor ine or chloramines present in dr ink ing water to maintain i ts qual i t y as i t passes through the water company’s network of p ipes and household p lumbing.

Risk assessment

a review under taken to ident i f y ac tual or potent ia l hazards to human heal th in a water treatment works and assoc iated supply system. Pr ior i t isat ion of r isk is based on cons iderat ion of l ikel ihood and consequence of the r isk occurr ing.

Secretary of State Secretary of State for Environment, Food and Rural Af fairs .

Selenium is an essent ia l e lement and a necessary d ie tary component . Amounts in dr ink ing water are usual ly wel l below the standard. A European health-based s tandard of 10μg/ l appl ies.

Service connect ion connect ion between the water company's main to a consumer’s property.

Service pipe any p ipe subject to mains water pressure or subject to mains pressure but for the c los ing of some valve.

Service reservoir a water tower, tank or other reservoir used for the s torage of treated water wi th in the d istr ibut ion system.

Sodium is a component of common sal t . I t is present in seawater and brack ish groundwater . Some treatment chemicals contain sodium. Concentrat ions in dr ink ing water are extremely low, but some water sof teners can add signif icant amounts to dr ink ing water where they are ins ta l led in homes or factor ies. A nat ional standard of 200mg/ l appl ies.

Springs groundwater appear ing at the surface at the outcrop of the junct ion of a permeable stratum with an impermeable s tratum.

Western reg ion

69

Sulphate occurs natura l ly in a l l waters and is dif f icu lt to remove by treatment. An indicator parameter with a guide value of 250mg/ l .

Supply pipe see service p ipe.

Supply point a point other than a consumer ’s tap author ised for the tak ing of samples for compl iance wi th the regulat ions.

Surface water untreated water f rom r ivers, impounding reservoirs or other sur face water source.

Taste can ar ise as a consequence of natura l processes in surface waters, par t icular ly between late spr ing and ear ly autumn. W ater treatment with act ivated carbon or ozone wi l l remove natura l substances caus ing taste. The s tandard relates to the evaluat ions of a panel of people assessing samples in the laboratory.

Technical audit the means of check ing that water companies are complying wi th their statutory obl igat ions.

Tetrachloroethane and Trichloroethene

are solvents that may occur in groundwater in the v ic in ity of industr ia l s i tes . W here necessary they are removed by spec ia l is t t reatment. A European health-based standard of 10μg/ l for the sum of both substances applies .

Tetrachloromethane is a solvent that may occur in groundwater in the v ic in i ty of industr ia l s i tes. Where necessary i t is removed by specia l is t water t reatment. A nat ional standard of 3μg/ l appl ies .

Time of supply the moment when water passes f rom the wate r company’s pipework in to a consumer’s p ipework.

Total indicat ive dose is a measure of the ef fect ive dose of radiat ion the body wi l l receive f rom consumpt ion of the water . I t is calculated only when screening values for gross a lpha or gross beta (radiat ion) are exceeded. An indicator parameter wi th a guide value of 0.10mSv/year.

Total organic carbon represents the tota l amount of organic matter present in water . An indicator parameter wi th a guide value of ‘no abnormal change’ .

Toxicology the s tudy of the health ef fects of substances.

Treated water water t reated for use for domestic purposes as def ined in the regulat ions.


70

Trihalomethanes are formed dur ing d is infect ion of water by a react ion between chlor ine and natural ly occurr ing organic substances. Their product ion is minimised by good operat ional pract ice. A European health-based standard of 100μg/l appl ies .

Trit ium is a radioact ive isotope of hydrogen. Discharges to the environment are str ic t ly control led and there is a nat ional programme of monitor ing surface waters . An indicator parameter wi th a guide value of 100Bq/ l .

Turbidity is a measure of the c loudiness of water. At treatment works, measurement is an important non-specif ic water qual i t y contro l parameter because i t can be monitored cont inuous ly on l ine and a larms set to a lert operators to deter iorat ion in raw water qual i t y or the need to opt imise water t reatment. An indicator parameter wi th a guide value of 1NTU. When detected at the consumer’s tap i t can ar ise f rom disturbance of sediment wi th in water mains. A nat ional s tandard of 4NTU appl ies in th is case.

Undertakings

legal ly b inding programmes of work agreed between a water company and the Chief Inspector of Dr ink ing Water to address actual or potent ial water qual i t y issues.

Vinyl chloride may be present in p las t ic pipes as a res idual of the manufactur ing process of polyviny l chlor ide (PVC) water p ipes. I ts presence in dr ink ing water is contro l led by product spec if icat ion. A European health-based standard of 0.5μg/ l appl ies .

Water supply zone a pre-def ined area of supply for establ ish ing sampl ing f requenc ies, compl iance wi th s tandards and informat ion to be made publ ic ly avai lable.

WHO World Health Organisat ion.

Wholesome/wholesomeness a legal concept of water qual i t y which is def ined by reference to s tandards and other requirements set out in the regulat ions.

Western reg ion

71

Annex 3 Not significant and minor drinking water quality events Nature Number of not signif icant and minor events Area a ffected (est imate of populat ion affected)

Chemical

SW T (1) Padstow, Cornwal l (3 )

WSX (1) Dur le igh , Somerset (3)

Discolourat ion

WSX (4) Keinton Mandevi l le , Somerset (2 ,785) Bath, Somerset (5 ,000) Hinton St George and Dinnington, Somerset (3 ,153) Beaminster , Dorset (2 ,959)

Loss of suppl ies / poor pressure

BRL (1 ) Eastvi l le , Br is to l (16,000)

SW T (2) Newquay, Cornwal l (2 ,070) Tiver ton, Devon (2,350)

VW P (1) Tidworth, W i l tsh i re (1 ,500)

WSX (2) L i t ton Cheney, W est Dorset (2 ,000) High Ham, Somerset (750)

Microbio log ica l

BRL (1 ) Radstock, Somerset (3)

WSX (3) Por lock, Somerset (3) Bishopstone , Gloucestersh i re (3) Hooke, Dorset (3 )

Publ ic concern

SW T (3) St Auste l l , Cornwal l (3) Boswinger, Cornwal l (3) St Blazey, Cornwal l (155)

WSX (5) Sparkford, Somerset (3) West Lavington, W i l tsh i re (3) Char l ton Horethorne, Somerset (3) Br idgwater Somerset on two occas ions (3)


72

Nature Number of not signif icant and minor events Area a ffected (est imate of populat ion affected)

Taste o r odour

BRL (4 ) Wot ton-under-Edge, Gloucestersh i re (3) Kingston Seymour, Nor th Somerset (3 ) Frampton Cot tere l l , South Gloucestersh i re (3) Shoscombe, Somerset (5)

SBW (1) Ferndown, Dorset (3)

SW T (2) Newton Abbot t , Devon (5) Tavis tock, Devon (5)

Total 31 –BRL (6) , SBW (1) , SWT (8) , VWP (1 ) , WSX (15)

38,785

Significant, serious and major drinking water quality events

Date and durat ion

Area Est imate of populat ion affected

Nature and cause of the event

Main act ions and f indings from the Inspectorate investigat ion

03 Jan 2012 For 4 weeks (W SX)

Sut ton Bingham raw water impounding reservo i r supplying Su t ton Bingham works serving consumers in Yeovi l area of Somerset .

No consumers d i rect ly a f fected –works out o f supply .

Media in te rest in p lanned works .

Wessex Water Services Ltd act ion:

Ceased p lanned work . DWI comments and f indings:

P lanned work be ing car r ied out on raw water reservo i r reported to media by a member of the publ ic who was cr i t ica l o f waste of wa ter dur ing a per iod of d rought .

Cr i t ica l o f the company for fa i l ing to in form DW I of media in terest , the company has s ince put in p lace measures to ensure a l l media in terest events ( i r respect i ve of actua l r i sk to water qual i t y) are not i f ied as requi red by In format ion Di rect ion.

Risk c lass i f icat ion: Sign i f icant

Western reg ion

73

Date and durat ion




02 Feb 2012 For 14 days (BRL)

Cheddar, Wedmore, Knol l areas in Somerset .

Not re levant . Increase in Cryptospor id ios is in the communi ty.

Bris tol Water Plc act ion:

Sampled af fected a rea.

Reviewed upst ream works t reatment process and catchment .

DWI comments and f indings:

Heal th surve i l lance data showed an increase in cryptospor id ios is in the communi ty ( f i ve reported cases) invest igat ions d id not show any l ink to d r ink ing water . Epidemio logy pointed to the cause as fore ign t ravel .


28 Feb 2012 For 24 hours (SW T)

Tot t i ford works supplying consumers in Dartmoor, Devon .

74.083 E.col i . South West Water Ltd act ion:


Invest igated laborato ry analys is and in tegr i t y o f bot t les .

Invest igated t reatment p rocess and catchment . DWI Comments and Findings.

The works is the subject o f a major upgrade , inc lud ing provis ion o f rap id g ravi ty f i l te rs , a contact channel , pH correct ion and oxidat ion fac i l i t ies . These changes, combined wi th the o ther act ions taken by the company, should prevent recur rence of th is event .



74

Date and durat ion




22 Apr 2012 For 24 hours (BRL)

F ishponds, Br is to l .

6 ,700 Rot ten eggs taste or odour due to p lanned work .


Review of procedures.

Sampled af fected a rea .

Provided bot t led wate r on request .


Cause was incor rect operat ion of network va lves which resul ted in s tagnant water enter ing the network.

Cr i t ica l o f p rocedures and invest igat ion .

Recommended that company puts in p lace measures to ensure that appropr ia te sample parameters are tested for dur ing water qual i t y events as requi red by Regulat ion 17 and 18.

Recommended company reviews i ts provis ion o f in format ion to ensure that the requi rements of the In format ion Di rect ion a re met .

Recommended company revises ca l l cent re scr ip ts to ensure that advice g iven to consumers regard ing safety of water is accurate and is based on evidence.


06 Jun 2012 For 48 hours (SBW )

Alderney works Bournemouth area, Dorset .

185,000 E.col i . Sembcorp Water Action:


Reviewed t reatment p rocess .

Reviewed raw water qua l i ty .


Cr i t ica l o f company invest igat ion of th is event .

Inspectorate audi t o f s i te showed def ic ienc ies in sampl ing pract ice re la t ing to s ter i l isat ion o f the taps and a lso label l ing and handl ing of samples. The s i te audi t ident i f ied that changes were needed in pract ices for ch i ronomid contro l and v is ib i l i ty o f d is in fect ion processes at s i te .

Undertak ing in p lace for mi t igat ion of r isks ident i f ied previous ly wi th locat ion of contact tanks below the s low sand f i l ters . The company has not ye t sat is f ied the requi rements for be ing re leased f rom th is undertak ing.


Western reg ion

75

Date and durat ion




08 Jun 2012 For 2 hours (SW T)

Bastreet works supplying consumers in Launceston, Cornwal l .

12,500 Cryptospor id ium . South West Water Ltd act ion :

Shut down t reatment works.


Repai red fau l ty po lye lec t ro ly te dos ing equipment . DWI comments and f indings:

Suggested on- l ine wate r qual i ty t rend da ta be improved so i t is quant i ta t i ve and presentat ion enables in terpretat ion .

Th is works is ident i f ied as being at r isk f rom Cryptospor id ium in the regulatory r isk assessment .


22 Jun 2012 For 2 days (SW T)

Al lers works supplying consumers in Tiver ton area, Devon .

79,000 Cryptospor id ium . South West Water Ltd act ion:


Review of t reatment process.

Review of catchment . DWI comments and f indings:

Th is works is ident i f ied as being at r isk of Cryptospor id ium in the regulatory r isk assessment and cont inuous moni tor ing is in p lace .

A subsequent event a t th is works where co l i form bacter ia and E.col i were detected led the Inspectorate to

put in p lace a Not ice requi r ing enhanced moni tor ing at th is s i te for microbio log ica l parameters in 2013.



76

Date and durat ion




29 Jun 2012 For 3 days (SW T)

Teignmouth , Devon .

12,173 Discolourat ion due to a mains burs t .

South West Water Ltd act ion:

F lushed mains.


Review of procedures. DWI comments and f indings:

Sampl ing was not t imely enough.

Recommended that company reviews i ts invest igat ional procedure to ensure that i t is t imely , covers the parameters of in terest and conf i rms the extent o f the event as requi red by Regulat ion 17 and 18.


30 Jun 2012 For 8 hours (W SX)

Rockwel l Green, Wel l ington, Somerset .

7 ,500 Discolourat ion due to p lanned work .



F lushed mains .

Rezoned the a rea (brought in wate r f rom a d i f fe rent area) .


Cr i t ica l o f fa i lure of company to ident i f y the potent ia l for d isco lourat ion pr ior to th is p lanned mains rehabi l i ta t ion work .

Suggested learn ing f rom event is incorporated in to d is t r ibut ion, maintenance and operat ion s t ra tegy (DOMS).


Western reg ion

77

Date and durat ion




07 Ju l 2012 For 2 days (SW T)

Pynes works, supplying consumers in Exete r , Devon.

122,580 Cryptospor id ium . South W est W ater L td act ion:

Increased ch lor ine res iduals at t reatment works.



Th is works is ident i f ie d as being at r isk of Cryptospor id ium in the regulatory r isk assessment .

Suggested company review on - l ine da ta befo re i t is inc luded in the company’s event report to ensure that i t i s accurate and in a form that is capable of be ing evaluated.


13 Ju l 2012 For 8 weeks (SW T)

Dr i f t works supplying consumers in Penzance W est Penwi th , Cornwal l .

50,752 Tr iha lomethanes and taste and odour.



Increased turnover in downstream reservo i rs .

Wrote to consumers and p laced not ice on websi te to apolog ise about ch lor ine taste and odour due to react ive ly commiss ion ing new GAC f i l t ra t ion process and fa i l ing to ad just ch lor ine dose.


The cause was an increase in organ ic mat ter in the raw water and fa i lure to ad just t reatment as necessary.

Recommended that the company p lans t imely warn ings to customers of expected changes in wate r qual i ty, par t icu lar l y as par t o f p lanned work, where r isk has been ident i f ied .

Cr i t ica l that the commiss ion ing of a new GAC process was t r iggered by a fa i lu re of t r iha lomethane s tandard in the d is t r ibut ion ne twork.

The company d id not adhere to the requi rements of sect ion 9(3)(g ) o f the In format ion Di rect ion ensur ing reports conta in consumer contact in format ion as appropr ia te.



78

Date and durat ion




06 Aug 2012 For 2 weeks (W SX)

Dur le igh works supplying consumers in Br idgwater , Somerset .

54,200 Col i form bacte r ia . Wessex Water Services Ltd act ion:

Increased ch lor ine res iduals at t rea tment works.


Shut down t reatment works.

Review of the t reatment process.

Reviewed Regulat ion 28 r isk assessment . DWI comments and f indings:

The company fa i led to ident i fy a cause of seasonal detect ions of co l i form bacter ia , but act ion p lan in re la t ion to d isso lved a i r f lo ta t ion p lant pu t in p lace

The company has updated i ts Regulat ion 28 r isk assessment us ing learn ing f rom th is event .


11 Sep 2012 For 1 week (W SX)

Taunton, Somerset .

128 Gastroente r i t is in propert ies on a pr ivate d is t r ibut ion network.



L ia ised wi th cont ractor work ing on p r iva te onward d is t r ibut ion network.


Cr i t ica l that no water f i t t ings inspect ion car r ied out and poor l ia ison between s takeholders invest iga t ing th is event to obta in and share sample resul ts taken by th i rd par ty to a l low vis ib i l i ty and ass is t invest igat ion o f even t .

Recommended that company develops cr i ter ia and procedures for t r igger ing water f i t t ings inspect ions.

Cr i t ica l that company d id not carry out a f i t t ings inspect ion at any of the propert ies and th is resul ted in not be ing able to demonstrate that company ne twork was protected.

Recommended that company puts in p lace measures to ensure compl iance wi th Regulat ion 17 and 18.


Western reg ion

79

Date and durat ion




19 Sep 2012 For 3 days (W SX)

Taunton, Somerset .

4 ,000 Discolourat ion due to a mains burs t .



Repai red main.


Provided an a l te rnat i ve supply by tanker /bowser .

F lushed mains.


Company invest igat ion and act ions sat is factory .

No recommendat ions or suggest ions made.


25 Sep 2012 For 72 hours (BRL)

Sing le commerc ia l property in Br is to l .

3 Petro l sp i l lage. Bris tol Water Plc act ion:



Issued a do not dr ink no t ice .

Carr ied out a water f i t t ings inspect ion .


Cause was sp i l lage o f fue l a f fec t ing p last ic service p ipe detected by wate r f i t t ings inspect ion made by the company.




28 Sep 2012 For 2 days (SW T)

Holemoor v i l lage, Devon.

23 Mains burs t . South West Water Ltd Action:

F lushed mains.

Issued a boi l wate r not ice.

Provided an a l te rnat i ve supply by tanker/bowser .


DWI Comments and Findings:

Company invest igat ion and act ions sat is factory.




80

Date and durat ion




28 Sep 2012 For 8 weeks (W SX)

Food premises in W interborne St ick land, Dorset .

3 E.col i . Wessex Water Services Ltd act ion:


Issued boi l wate r advice .

Water f i t t ings inspect ion found that the s torage tank and long supply p ipe caus ing deter iorat ion in qual i t y o f water . F i t t ings Regulat ions Not ice issued requi r ing improvements to the tank.


Th is event arose as a consequence of a water sample taken by an Envi ronmenta l Heal th Of f icer (EHO) as par t o f a food safety inspect ion. The water company recognised that th is p roperty had been a t the centre of a previous water qual i t y event .

Company invest igat ion and act ion sat is fa ctory. Risk c lass i f icat ion: Sign i f icant

11 Oct 2012 For 5 days (SW T)

Tamar works supplying consumers in Bude, Cornwal l .

20,700 Pest ic ide (meta ldehyde).



Review of catchment .

Arranged to submi t an under tak ing to car ry out appropr ia te invest iga t ions and act ions wi th o ther s takeholders .


Meta ldehyde was detected in raw water in the impoundment reservo i r for the f i rs t t ime , poss ib ly as a consequence of land run of f a f ter heavy ra i n fa l l .

The company was advised to submi t an undertak ing. Risk c lass i f icat ion: Sign i f icant

Western reg ion

81

Date and durat ion




12 Oct 2012 For 1 day (SW T)

Al lers works supplying consumers in Tiver ton, Bampton, South Mol ton, Cul lompton, Honi ton Lyme Regis , Devon.

78,663 E.col i . South West Water Ltd act ion:


Review of t reatment process .

Cleaned and inspected contact tank .

Audi ted labora tory method. DWI comments and f indings:

A Not ice was put in p lace requi r ing enhanced moni tor ing for microbio log ica l parameters .


01 Nov 2012 For 9 hours (SW T)

St . Dennis , Cornwal l .

140 Loss of suppl ies /poor pressure due to th i rd par ty damage to mains.


Issued a precaut ionary bo i l water not ice.

Raised ch lor ine res idua ls .


Repai red main. DWI comments and f indings:

The company was advised to use the in fo rmat ion gained dur ing th is event to in form i ts DOMS programme .

Suggested that the company should revis i t i ts po l icy of on ly provid ing in format ion to contractors carry ing out p lanned work when requested, company encouraged to take a proact i ve approach.



82

Date and durat ion




17 Nov 2012 For 72 hours (BRL)

Shipton Moyne and Tetbury, Gloucestersh i re .

250 E.col i . Bris tol Water Plc act ion:

Sampled af fected a rea a f ter unsat is factory mains repai r sample.

Issued a boi l wate r not ice.

Increased ch lor ine at supplying works . DWI comments and f indings:

Cr i t ica l that the company fa i led to take samples to invest igate th is event and fa i l ed to meet requi rements of Regulat ion 10.

Recommended that the company revises i ts p rocedures for sampl ing fo l lowing loss of water suppl ies .

Cr i t ica l that va lve operat ion procedures were not fo l lowed and there was unauthor ised opera t ion of a va lve which is l ike ly to have cont r ibuted to negat ive pressure drawing contaminated water through fau l ty and f looded a i r va lves.

The company has taken act ions to rep lace fau l ty va lves and modi fy p rocedures to prevent a recurrence o f th is event .


21 Nov 2012 For 5 days (W SX)

Taunton, Somerset .

23 E.col i . Wessex Water Services Ltd act ion:

Sampled af fected a rea a f ter unsat is factory mains repai r sample .

Issued boi l wate r advice .

Provided advice to the consumer . DWI comments and f indings:

Invest igat ion by company showed that th is event was caused by ingress of ground water whi le a repai r o f a main was being made.

The Inspectorate requi red the company to demonstrate that s ta f f had received the addi t ional t ra in ing ind icated by the company in the i r response.


Western reg ion

83

Date and durat ion




23 Nov 2012 For 1 day (W SX)

Maundown works supplying consumers in West Somerset .

40,000 E.col i . Wessex Water Services Ltd act ion:


Review of t reatment processes .

Increased ch lor ine res iduals at works . DWI comments and f indings:

The cause was a laboratory e rror , the resul t was f rom a raw water sample.


No recommendat ions or suggest ions made . Risk c lass i f icat ion: Sign i f icant

05 Dec 2012 For 24 hours (W SX)

Boyne Hol low works supplying consumers in Shaf tesbury, Dorset .

15,334 Cryptospor id ium . Wessex Water Services Ltd act ion:


Review of catchment .

Review of t reatment processes . DWI comments and f indings:

No recommendat ions or suggest ions made. Risk c lass i f icat ion: Sign i f icant

05 Dec 2012 For 4 weeks (BRL)

Barrow Gurney, Somerset .

43 Petrochemical de l ivery e rror to a pr ivate wate r supply tank.


Sampled af fected a rea fo l lowing report o f ‘o i l y ’ tas te by res ident . Supply subsequent ly iden t i f ied as p r iva te supply system wi th mains fed tanks.

Issued a do not dr ink no t ice.



The factors contr ibut ing to th is event were

water tanks were not secured by locks.

water and o i l tanks were not c lear l y label led . Risk c lass i f icat ion: Sign i f icant


84

Date and durat ion




12 Dec 2012 For two days (SBW )

Wimborne, Dorset .

6927 Discolourat ion due to p lanned work .

Sembcorp Bournemouth Water Ltd act ion:


F lushed mains . DWI comments and f indings:

Cr i t ica l that the company fa i led to provide in format ion wi th in the t imescales spec i f ied in the In fo rmat ion Di rect ion.

Reminded the company that the in i t ia l no t i f icat ion of events should fo l low the cascade proced ure.


13 Dec 2012 For 74 hours (W SX)

Fulwood, Tru l l , Taunton, Somerset .

3 Chemical tas te or odour.


Issued a do not dr ink no t ice .

Sampled area.

Issued bot t led water on request . DWI comments and f indings:

Cr i t ica l that the company d id no t issue a wr i t ten not ice re la t ing to the in f r ingements of the f i t t ings regulat ions to the householder and tha t the householder was in formed in a le t ter da ted 20 February 2013 that samples f rom both the hot and co ld water systems in the i r p roperty were sat is facto ry and showed no evidence of chemicals f rom the so lar heat ing system, whi le in fac t chemicals used to prevent f reezing of the system were s t i l l present in the hot water system.

Suggested that the company uses learn ing f rom the s imi lar event a t Up ton Eco Housing Development to in form i ts appra isa l o f r i sks to water qual i ty where these systems are f i t ted.


Note: A complete table of events in England and W ales in 2012 can be found on the CD in the fo lder. I t is named Signif icant drinking water events in England and Wales 2012.pdf . I t is also avai lable on the DW I webs i te (ht tp:/ /www.dwi.gov.uk).

Western reg ion

85

Annex 4 Planned drinking water quality improvements

Company Parameter , hazard or dr iver

Site Due for complet ion*

Status* Legal Instrument

BRL Cryptospor id ium Cheddar 30-Jun-14 Ongoing Not ice

BRL Cryptospor id ium L i t t le ton 31-Dec-13 Ongoing Not ice

BRL Cryptospor id ium Pur ton 31-Dec-11 Completed

05-Jan-12 Not ice

BRL Cryptospor id ium Shipton Moyne 31-Dec-12 Completed

01-02-13 Not ice

BRL Cryptospor id ium Stowey 31-Dec-13 Ongoing Not ice

BRL I ron Trunk mains rehabi l i ta t ion

31-Mar-15 Ongoing Undertak ing

BRL Lead Sherborne 31-Ju l -13 Ongoing Not ice

BRL Meta ldehyde Banwel l catchment 31-Mar-15 Ongoing Undertak ing

BRL Meta ldehyde L i t t le ton and Purton catchments


BRL Meta ldehyde Stowey catchment 31-Mar-15 Ongoing Undertak ing

BRL Ni t ra te Frome 04-Sep-14 Ongoing Undertak ing

BRL Tota l t r iha lomethanes

L i t t le ton 31-Dec-11 Completed

15-Dec-12 Undertak ing

SBW

Iron, turb id i ty and polycyc l ic aromat ic hydrocarbons

Dis t r ibut ion system 31-Mar-15 Ongoing Undertak ing

SW T I ron and turb id i ty

Greatwel l 30-Jun-12 Completed

17-Aug-12 Undertak ing

SW T Lead Dr i f t , Restormel Centra l , Dot ton and Pynes Centra l


SW T Manganese Tot t i ford 31-Mar-12 Completed

12-Mar-12 Undertak ing

SW T Pest ic ides Dr i f t 31-Mar-12 Completed

30-Mar-12 Undertak ing

SW T Pest ic ides Restormel 31-Dec-14 Ongoing Undertak ing

SW T Tota l t r iha lomethanes

Wendron 31-Dec-14 Ongoing Undertak ing

WSX

Chlor to luron, isoproturon, MCPA, MCPB, 2,4-D and metazachlor

Fr iar W addon 31-Jan-11 Completed

01-Jan-12 Undertak ing

WSX

Col i form bacter ia

Moorbrake Camp 31-Mar-13 Completed

03-04-13 Not ice

WSX Cryptospor id ium Dunkerton 31-Mar-13 Completed

28-02-13 Not ice

WSX Cryptospor id ium Tatworth 31-Mar-13 Completed

28-02-13 Not ice

WSX Cryptospor id ium To l le rdown 31-Aug-13 Ongoing Not ice


86

Company Parameter , hazard or dr iver

Site Due for complet ion*

Status* Legal Instrument

WSX Cryptospor id ium W iddenham 31-Aug-13 Ongoing Not ice

WSX I ron, manganese and turb id i ty

Trunk mains renova t ion


WSX

Isoproturon, pest ic ides, mecoprop, ch lor to luron and taste and odour

Sut ton Bingham 31-Mar-14 Ongoing Undertak ing

WSX Lead Dis t r ibut ion system 31-Mar-15 Ongoing Undertak ing

WSX Meta ldehyde Dur le igh catchment 31-Mar-15 Ongoing Undertak ing

WSX Ni t ra te

Dunkerton, Chi r ton , Fonth i l l B ishop , Sturminster Marshal l /Shapwick , Hooke, Bulb r idge and W ylye


WSX Taste and odour Blashford 30-Jun-13 Ongoing Undertak ing

WSX E.col i Const i tu t ion Hi l l 31-Dec-13 Ongoing Not ice

*Dates used are those for the complet ion of the agreed programme of work. There is a fur ther per iod of 12 months before a p rogramme is o f f ic ia l ly c losed to ascer ta in the benef i ts o f the work to consumers.

Acknowledged actions to sustain safe, clean drinking water

Additional acknowledged act ions

to mitigate r isk (as at Dec 2008)

Acknowledged act ions completed (as at Dec 2011)

Acknowledged act ions completed (as at Dec 2012)

38 25 26

Western reg ion

87

Annex 5 Competition in the water industry

The following table indicates the extent of competit ion in the water industry in England and Wales .

Inset appointments in place in 2012

Site Appointee Incumbent and region Status

Shotton Paper , Shotton

Alb ion W ater Dŵr Cymru W elsh W ater , Wales

Supplying water

Buxted Chicken, Fl ix ton

Angl ian W ater Essex and Suf fo lk W ater, Centra l and Eastern region

Supplying water

W ynyard, near Wolviston

Har t lepool Water Nor thumbr ian W ater, Nor thern region

Supplying water

Berryf ie lds , Aylesbury

Independent Water Networks Ltd

Thames Water, London and South East region

Supplying water

Brook lands, Mi l ton Keynes


Angl ian W ater, Centra l and Eastern region

Supplying water

Great Bi l l ing W ay, Nor thampton



Supplying water

Kings Cross, London



Supplying water

Long Crof t Road, Corby



Supplying water

Pr iors Hal l , Corby Independent Water Networks Ltd


Supplying water

The Br idge, Dar tford



Supplying water

Media City, Salford Quays

Peel Water Networks Ltd

Uni ted Ut i l i t ies, Nor thern region

Supplying water

Brewery Square, Dorchester

SSE W ater Wessex W ater, Western region

Supplying water

Bromley Common, Bromley

SSE W ater Thames Water , London and South East region

Supplying water

Farndon Road, Market Harborough

SSE W ater Severn Trent W ater/Angl ian Water, Centra l and Eastern region

Supplying water

Grayl ingwel l , Chichester

SSE W ater Portsmouth W ater/Southern Water, London and South East region

Supplying water

Great Western Park , Didcot

SSE W ater Thames Water, London and South East region

Supplying water

Hale Vi l lage, Tottenham


Supplying water

Kennet Is land, Reading


Supplying water

Kingsmere, Bicester


Supplying water

L lani l id Park , South W ales

SSE W ater Dŵr Cymru W elsh W ater, Wales

Supplying water

New South Quarter, Croydon


Supplying water


88

Site Appointee Incumbent and region Status

Norwich Common, W ymondham

SSE W ater Angl ian W ater, Centra l and Eastern region

Supplying water

Park Views, Epsom


Supplying water

Rivers ide, Bark ing SSE W ater Essex and Suf fo lk Water/Thames W ater, Centra l and Eastern region

Supplying water

The Portway, near Sal isbury

SSE W ater Wessex W ater, Western region

Supplying water

MoD T idworth, near Andover

Veol ia W ater Projects

Wessex W ater, Western region

Supplying water

New inset appointments in 2012

Site Appointee Incumbent and region

Status

Oakham North, Oakham


Severn Trent W ater, Centra l and Eastern region

Appointment granted

Kennet Is land (Phase 7) , Reading


Appointment granted

Marine W harf , Deptford


Appointment granted

River l ights (T ideway Wharf ) , Bat tersea


Appointment granted

Western reg ion

89

Annex 6 Water company indices

Key

Bristol Water (BRL)

Cholderton and Distr ict Water (CHO)

Sembcorp Bournemouth Water (SBW)

South West Water (SWT)

SSE Water (SSE)

Veol ia Water Projects (VWP)

Wessex Water (WSX)

Industry average (Industry)

Overall drinking water quality

99.94 99.95 99.96 99.97 99.98 99.99 100.00

Industry

SWT

WSX

BRL

SBW

SSE

VWP

CHO

Percentage compliance


90

Process control index

99.92 99.93 99.94 99.95 99.96 99.97 99.98 99.99 100.00

SWT

WSX

Industry

VWP

SBW

CHO

BRL


Disinfection index

99.88 99.90 99.92 99.94 99.96 99.98 100.00

SBW

Industry

SWT

WSX

VWP

CHO

BRL


Western reg ion

91

Distribution maintenance index

99.80 99.85 99.90 99.95 100.00

Industry

SWT

BRL

SBW

WSX

VWP

SSE

CHO


Reservoir integrity index

98.50 99.00 99.50 100.00

CHO

Industry

SBW

WSX

SWT

BRL

VWP



92

Bristol Water plc

Water supply arrangements

Company assets Water supplied

Number of treatment works 17 Water suppl ied (Ml/day)

301

Number of service reservoirs 170 Percentage f rom surface sources

81.5

Number of water supply zones 52 Percentage f rom ground sources

11.9

Length of mains p ipe (km) 6,702 Percentage f rom mixed sources

6.6

Population served Area of supply

Gloucestershire, Wiltshire, Bristol , Somerset

Populat ion supplied 1,201,000

Number of local author it ies 9

Drinking water quality summary data

Company f igure Industry average

2010 2011 2012 2012

Overal l drinking water quality* 99.96% 99.96% 99.99% 99.96%

Water t reatment

Process Contro l Index 99.86% 99.99% 100% 99.99%

Dis infect ion Index 99.97% 99.99% 100% 99.97%

Distribution systems

Dis tr ibut ion Maintenance Index 99.89% 99.59% 99.94% 99.88%

Reservoir In tegr i ty Index 99.99% 99.98% 99.99% 99.95%

Building water systems

Parameters inf luenced by domest ic water systems

99.96% 99.92% 99.97% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers

Tota l number 1,028 888 935 N/A

Rate per 1 ,000 populat ion 0.90 0.77 0.78 1.33

Acceptabi l ity of water to consumers

Tota l number 2,935 2,567 2,588 N/A


Complaints to the Drinking Water Inspectorate

A tota l of 1 consumer of Br isto l W ater p lc d irect ly contacted DWI in 2012.

Note: Summary resu l t s for each company o f tes ts for i nd i v idua l parameters are supp l ied on the DW I webs i te a t h t tp : / /www.dwi .gov.uk

* Overa l l d r ink ing water qua l i t y as rep resented by mean zona l compl iance fo r 39 parameters .

http://www.dwi.gov.uk/

Western reg ion

93

Cholderton and District Water Company Ltd Water supply arrangements



2.1


0


100

Length of mains p ipe (km) 30 Percentage f rom mixed sources

0


Small parts of Wiltshire and Hampshire

Populat ion supplied 3,000




2010 2011 2012 2012

Overal l drinking water quality* 100% 100% 100% 99.96%

Water t reatment

Process Contro l Index 100% 100% 100% 99.99%

Dis infect ion Index 99.36% 100% 100% 99.97%


Dis tr ibut ion Maintenance Index 100% 100% 100% 99.88%

Reservoir In tegr i ty Index 100% 100% 99.06% 99.95%



100% 100% 100% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers

Tota l number 0 0 0 N/A

Rate per 1 ,000 populat ion 0 0 0 1.33



Rate per 1 ,000 populat ion 0 0 0 1.90


No consumers of Cholder ton and Distr ic t W ater Company Ltd d irec t ly contacted DW I in 2012.





94

Sembcorp Bournemouth Water Ltd Water supply arrangements



105


84


16


0


Parts of Dorset , Hampshire and Wiltshire





2010 2011 2012 2012

Overal l drinking water quality* 99.94% 99.98% >99.99% 99.96%

Water t reatment


Dis infect ion Index 99.87% 99.95% 99.92% 99.97%


Dis tr ibut ion Maintenance Index 100% 99.82% 99.94% 99.88%

Reservoir In tegr i ty Index 100% 100% 99.95% 99.95%



99.73% 99.95% 99.96% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers







No consumers of Sembcorp Bournemouth Water Ltd d irec t ly contacted DWI in 2012.




Western reg ion

95

South West Water Ltd Water supply arrangements



430


93


6


1


Devon, Cornwall, Somerset (part) , Dorset (part)





2010 2011 2012 2012


Water t reatment

Process Contro l Index 100% 100% 99.95% 99.99%

Dis infect ion Index 99.97% 99.97% 99.98% 99.97%


Dis tr ibut ion Maintenance Index 99.89% 99.94% 99.91% 99.88%




99.91% 99.97% 99.93% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers

Tota l number 1,812 1,113 1,602 N/A



Tota l number 11,085 11,653 9,377 N/A



A tota l of 2 consumers of South W est Water Ltd d irect ly contacted DWI in 2012.


* Overa l l d r ink ing water qua l i t y as rep resented by mean zona l compl iance fo r 39

parameters .



96

SSE Water

Water supply arrangements



1


59


28


13


Old Sarum, near Sal isbury;

Hale Vi l lage, Tottenham; Grayl ingwell , Chichester; Bromley Common, Bromley; Kennet Island, Reading; Park Views, Epsom; Llani l id Park, South Wales; Kingsmere, Bicester; Great Western Park, Didcot; Barking Riverside , Barking; Farndon Road, Market Harborough New South Quarter, Croydon; Brewery Square, Dorchester; and Norwich Common, Wynmondham





2010 2011 2012 2012

Overal l drinking water quality* 100% 100% >99.99% 99.96%

Water t reatment

Process Contro l Index N/A N/A N/A 99.99%

Dis infect ion Index N/A N/A N/A 99.97%



Reservoir In tegr i ty Index N/A N/A N/A 99.95%



100% 100% 100% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers







No consumers of SSE Water d irect ly contacted DW I in 2012.

Note: Summary resu l t s for each company o f tes ts for i nd i v idua l parameters are supp l ied on the DW I webs i te a t h t tp : / /www.dwi .gov.uk * Overa l l d r ink ing water qua l i t y as rep resented by mean zona l compl iance fo r 39 parameters .


Western reg ion

97

Veolia Water Projects Ltd Water supply arrangements


Number of treatment works 2 W ater suppl ied (Ml/day)

3.5


0


100


0


Tidworth, Wil tshire Populat ion supplied 8,000




2010 2011 2012 2012

Overal l drinking water quality* 100% 100% 100% 99.96%

Water t reatment


Dis infect ion Index 100% 100% 100% 99.97%



Reservoir In tegr i ty Index 100% 100% 100% 99.95%



100% 100% 100% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers


Rate per 1 ,000 populat ion 0.12 0 0 1.33





No consumers of Veolia W ater Projects Ltd d irect ly contacted DWI in 2012.

Note: Summary resu l t s for each company o f tes ts for i nd i v idu a l parameters are supp l ied on the DW I webs i te a t h t tp : / /www.dwi .gov.uk




98

Wessex Water Services Ltd Water supply arrangements



332


27


71


2


Large parts of Somerset , Dorset and Wiltshire, small areas of Gloucestershire and Devon





2010 2011 2012 2012


Water t reatment

Process Contro l Index >99.99% 100% 99.98% 99.99%

Dis infect ion Index 99.95% >99.99% 99.99% 99.97%


Dis tr ibut ion Maintenance Index 99.97% 99.91% 100% 99.88%




99.94% 99.92% 99.93% 99.89%

Consumer contacts


2010 2011 2012 2012

Informing consumers

Tota l number 1,051 1,066 1,297 N/A



Tota l number 3,224 2,988 3,050 N/A



No consumers of W essex W ater Services Ltd d irec t ly contacted DWI in 2012.

Note : Summary resu l t s for each company o f tes ts for i nd i v idua l parameters are supp l ied on the DW I webs i te a t h t tp : / /www.dwi .gov.uk



Western reg ion

99

Annex 7 Information relating to public water supplies published by the Inspectorate in 2012 Information Letters Ref Title

01/2012 Update of the Inspectorate’s structure

02/2012 Arrangements for demonstrat ing that the laboratory analysis of

samples of drinking water and the associated report ing of

analyt ical results meet regulatory requirements

03/2012 Publ icat ion of research report on human pharmaceuticals in raw

and treated r iver water to inform regulatory r isk assessment

methodology

04/2012 Water supply hygiene – summary f indings of technical audits of

distr ibut ion depots and associated network opera tions between

July and November 2011

05/2012 Collect ion of data under the Pr ivate Water Suppl ies Regulat ions

2009 and the Private Water Suppl ies (Wales) Regulat ions 2010

06/2012 Regulat ion 15 compliance arrangements

07/2012 Publ icat ion of further research on nitrosamines in water

treatment coagulants and drinking water

08/2012 Outline of the Drinking Water Inspectorate cost recovery regime

09/2012 The Water Industry (Suppl ier ’s Information) Direct ion 2012

The le t te rs , and the i r assoc ia ted annexes , ca n be found on the Inspec tora te ’s webs i te a t ht tp : / / www. dwi . def ra .gov.uk /s takeholde rs / in fo rmat ion - le t te rs / index.h tm

Technical guidance

Joint Drinking Water Inspectorate/Environment Agency Guidance: The

Contr ibut ion of the Water Supply (Water Quality) Reg ulat ions to the

implementat ion of the Water Framework Direct ive in England and Wales

Copies o f the above gu idance can be found on the Inspec tora te ’s webs i te a t ht tp : / / www. dwi . def ra .gov.uk /s takeholde rs /gu idance -and-codes -o f -prac t ice /


100

Research

Ref Title

DWI 70/2/209 Impacts of Lining Materials on Water Quality

DWI 70/2/231 Targeted monitoring for human pharmaceuticals in

vulnerable source and f inal waters

DWI 70/2/235 Desk-based study of current knowledge on Veter inary

Medicines in drinking water and est imation of potential

levels

DWI 70/2/239 Investigation into the potent ial formation and removal of

nitrosamines in drinking water treatment

DWI 70/2/244 Impact of language and cognit ion on compliance dur ing a

natural disaster – and improving communicat ion on

Cryptosporidium and ‘Boi l Water’ notices

DWI 70/2/246 Review of the r isks posed to dr inking water by man -made

nanopart ic les

DWI 70/2/251 A survey of tap water consumption patterns amongst

chi ldren under 16 years of age

DWI 70/2/257 A review of sk in irr itat ion and tap water quality

DWI 70/2/259 Potent ial opt imisation and improvement of the Mean

Dissolved Oxygen Difference (MDOD) test to assess the

abi l i ty of non-metal l ic materials of construct ion to

enhance microbial growth

DWI 70/2/263 Health impacts f rom extreme events water shortages

DWI 70/2/266 A review of latest endocrine disrupting chemicals research

implicat ions for drinking water

DWI 70/2/269 Quantifying the benef its of water quality catchment

management init iat ives

DWI 70/2/279 Workshop on Val idat ing the cause of coliform failures in

drinking water

Copies o f res earch repo r ts and exec ut ive summar ies can be found on the Inspec tora te ’s webs i t e at h t tp : / / www.dwi .def ra .gov.uk / res earc h/comple ted - researc h/2000todate .h tm

Western reg ion

101

Annex 8 Distribution of private water supplies

Drinking water2012Public water supplies in the Western region of EnglandJuly 2013A report by the Chief Inspector of Drinking Water

Drin

king

water 2

01

2

Public water supplies in the W

estern region of England

PB 13951

Drinking Water Inspectorate | Nobel House, 17 Smith Square | London | SW1P 3JR | Tel: 0300 068 6400

www.dwi.gov.uk

Drinking water 2012 · 2013. 7. 12. · Drinking water 2012 4 Chapter 1: Summary Chapter 1:...

Documents

Transcript of Drinking water 2012 · 2013. 7. 12. · Drinking water 2012 4 Chapter 1: Summary Chapter 1:...