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28.1 Organization and managementThe organization of water supplies in Britain, as in other partsof the world, has evolved from initiatives by private com paniesan d public corporations. This situation still exists in m any partsof th e world, but in Britain a f ramework of organization an dmanagement1 has been created by successive Acts of Parliamentstarting with the W aterworks Clauses Act, 1874 through to theWate r Act 1973 (Eng land and Wales) and the Local Go vern-ment (Scotland) Act 1973. Further modifications were intro-duced in the Water Bill 1983.In England an d Wales, the 1973 Act created a framework ofriver basin management, with ten regional authorities respon-sible for the com plete hydrological cycle including conse rvation,water resources, treatment an d distribution, land drainage,sewerage and sewage treatment. However, in Scotland watersupply and sewage are the responsibility of the district council,except in the case of the Central Scotland Water DevelopmentBoard who act as a bulk sup ply authority. River purification isthe respon sibility of separate b oards except in the areas of theisland district councils.The Scottish pattern of management and organization ofwater supply, together with agent water companies (as inEngland an d Wales) has been adopted in m any English-speak-ing countries in local forms to comply with th e form ofgovernment, but there is a movement towards the more logicalformat of total river basin m anagement.

28.2 Present consumption andestimated demandDem and for water varies according to the type of su pply areabut may generally be considered under the three headings ofdomestic, industrial an d agricultural. Within th e year, th emonthly and weekly totals will vary considerably due to seaso-na l effect (wet or dry periods) and socio-economic effects (e.g.holiday periods, festivals, growth seasons). There will also bedaily variations within each week and peak hours during eachd a y . A peak hou rly rate of around 3 times the average rate needsto be considered in the design of distribution systems, and inrespect of local storage requirements.Domestic consumption assessments in Britain during th eperiod 1976-78 are summarized in Table 28.1, together withtypical figures arising from studies in other countries. In Britaindomestic supplies are not generally m etered2 but in most othercountries dom estic meters are a com m on feature. It is dou btfulif metering offers an y saving in cost, bu t with strict supervisionand control it can assist in controlling demand using an increas-ing scale of charges at higher rates of consumption.T a b l e 2 8 . 1 D o m e s tic c o n s u m p t io n p e r h e a d (1976-1978)Area or Consumption (I/head/day)country average rangeEngland & Wales 200 140-330Scotland 275 240-350London (urban) 260 Thames (rural) 210 Middle East (arid) (standpipes) 50-450Far East (tropical) 120-400

28.2.1 Domestic consumption (details)A typical breakdown of the present consumption and anestimate of future demand was made for a group of six selected

28.2.2 Industrial consumptionNo generalization can be made as the industrial consumption ineach town varies considerably according to the nature of theindustry both in quanti ty an d quality requirements. The water isgenerally required during the working day and this factor m ustbe taken into account in the design of pumps, pipes andreservoirs as it affects the peak rates of flow. As generalguidance the following examples are typical.

(1) For brewing, the quantity of water is substantially theamount brewed, but for beer th e water is preferably hard;for stout, soft; cider must be made from pure soft waterwithout iron.(2 ) Canning is best done with hard wate r (except for peas), andiron must be less than 0.5 mg/1: anyth ing between 20 and40 I/kg canned.(3) The dyeing industry requires soft, iron-free water, an dabout 10 0 I/kg, m ercerizing textiles takes 25 0 I/kg.(4) Industries such as distilling, ice-making and mineral-water-making require large am ounts of water, plus that for powerpurposes in steam-raising.(5) Leather requires 80 I/kg of raw hide tanned, water rich insulphates being preferred. Rubber requires 70 I/kg pro-cessed.(6 ) Paper or cardboard manufacture requires anythingbetween 60 and 360 I/kg.(7) A ton of soap requires about 22001 of water in itsmanufacture.(8 ) In the UK, sugar beet takes about 5 I/kg used in washingthe beet, dissolving the sugar, transporting the material inthe factory and in steam-raising.(9) In the heavier industries the following quantities m ay betaken as approximate, e.g. railways take about 0.221/1000kg of goods carried per kilometre. Cement takes3 I/kg. Coke might consume 13 to 181 of crude water perkilogram for cooling. Electricity works take 671 of crude

Water Undertakings in south-east England by Sharp in 1967.32This is shown in Table 28.2.T a b l e 2 8 .2 B r e a k d o w n o f d o m e s t ic c o n s u m p t io n ( 1 9 6 7 )

ComponentDrinking andcookingDishwashing an dcleaningLaundryPersonal w ashingand bathingCloset flushing andgarbage disposalCar washingGarden use andrecreationWaste indistributionTotal

Estimated 1967average consumption

gallons/head/day

133

1011

15

34

litres/head/day

4.51 3 . 51 3 . 54 5 . 550

4.52 2 . 5

154

Forecast of possibleaverage consumptionin 2000gallons/head/day

145

1314168

52

litres/head/day

4.5182 2 . 5596 3 . 54.52 7 . 53 6 . 5

236

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water pe r kilowatt generated, fo r make up or loss incooling towers, and 1.51 of fresh water per kilowatt forboilers. Steelworks would consume some 91 of mostlycrude water per kilogram of steel man ufactured.(10) Th e cost of industrial water or metered supplies variesconsiderably but is generally in the range 2p to 1Op pe r1000.28.2.3 Agricultural requirementsIn addition to the hum an population, allowance must be m adein a dairy farming district for the cow population. A cowrequires as much as 135 to 180 I/day and there may be specialrequirements such as for bottling - 1001 milk means 2001 ofwater; ma nufacturin g 455 kg dried milk needs 5501,455 kg alumneeds 45001, 455 kg cheese needs 7501. Where intensive fruitfarming is practised a complete network of pipes is requiredthrougho ut an orchard for treatm ent and irrigation. Similarly,considerable quantities of water are required to maintain bowl-ing greens, golfcourses and racecourses, and overhead irrigationof crops by rotary sprinklers is on the increase. In the ThamesValley a total of 90 Ml/day has been estimated as the require-m ent for irrigation by the year 2000. Very high consumptions ofthe order of 50 000 to 100 0001/ha per day would be required bya m arket gardener, and for tomatoes und er glass approxim ately20 0 0001/ha pe r day.Again, the watercress industry 4 at certaintimes of the year consumes very large quantities of water andm ay requ ire between 2.5 and 5.7 m illion 1/ha per day. Paradoxi-cal as it m ay seem, m ore water may be required in winter to keepwatercress from freezing than in summer to keep it fromscorching.5

28.2.4 Fire protectionGenerally, hydrants are spaced not more than 13Om apart.Important buildings may require additional protection, i.e.more than two hydrants within 90 m. For less important build-ings one hydrant within 140 m may suffice. Hydrants should be6 m or m ore away from buildings, are best placed at crossings orcorners, and are usu ally fixed on short 80 mm branches from them ain which should not be less than 100 mm . Fire mains shoulddeliver 5501/min at each hydrant expected to be in use at thesame time (generally two). As pressure in a main to commandthe highest bu ildings is generally impracticable, fire engines areused to deliver 1200 to 20001/min to a height of 50 m through a24-mm dia. nozzle; the larger fire engines deliver up to 45001/min. A residual pressure of 3 m at the ground is desirable toavoid the engine creating a vacuum in the main on the suctionside.In town s the calculation for the distribution o f water is basedon very general assumptions of the am oun t of water required atany given moment, and it may not be practicable to designadequately for fire protection if the mains are assumed to betaking th e maximum hour's domestic an d industrial require-ments as well. A good practical arrangement of valves andhydrants based on experience and checked occasionally bysimple network analysis is of more value than any very exactcalculations. Nowadays the fire authorities work closely withthe water authorities to determine the positions of fire hydrants.28.2.5 WasteSome consumption of water by waste is inevitable and fewstatutory undertakers can seriously claim a figure of less than10%, whilst in some areas where pressures are higher or themains and services are old or in poor condition, or whereefficient waste prevention m ethods are not applied, the wastagemay amount to as much as 50% or more. Waste m ay be due to a

number of factors including: (1) leakage from reservoirs, mainsan d other works of an undertaking, and from consumers' pipesand fittings through apertures, fractures, defective joints; (2 )faulty washers and valve seatings; (3) bad design, failure to turnoff taps; and (4) in all cases leakage and waste are intensified byunduly high pressures. Waste can be detected by detailedexamination of the distribution system or house-to-house in-spection, apart from a detailed check on the m ain reservoirs andaqueducts, etc.28.2.5.1 Examination of the systemIt is best to examine the water system section by section betweenmidnight an d 5.00a.m. an d check the night flow by a metercapable of reading small flows and recording them on a chart. Aspecific test on a 12mm lead pipe under 3.2kgf/cm 2 pressuregave a loss of 46 000 I/day for a 0.6 cm hole, 17 000 I/day for a0.3cm hole and 1600 I/day for a 0.15cm hole. Tests on newlylaid mains often call for a loss not exceeding 1 I/da y percentimetre of diameter pe r kilometre of length. House-to-houseinspections are probably in most cases the most effective way ofchecking waste. A dripping tap wastes up to 500 I/day and onerunning full as much as 10 000 I/day . The provision by the waterauthority of facilities for the rewashering, renewal and adjust-ment of taps, and repairs to service pipes at the lowest possiblecost, undoubtedly encourages consumers to report leakagespromptly and is an overall economy. In recent years severalm ore sophisticated systems 6 have been developed to detect leaksin mains, and to identify the precise points of leakage, thussaving a lot of abortive exploratory excavation.

28.3 Transmission and distribution ofwaterWater may be transmitted under gravity along open or coveredchannels, through tunnels or through pipes.7 Open channels areoften used for catchwaters, waste-water channels or for riverintakes to pumping stations in pumped storage schemes. Nowa-days they are not generally used for the transmission of treatedwater due to the danger of pollution. In some cases canals areadapted as aqueducts for the transmission of water. Some largeaqueducts have been constructed with sections of coveredchannel constructed by 'cut an d cover' methods an d modernpractice is to construct these of plain or reinforced concrete.Where an aqueduct is required to pass through ground appre-ciably higher than the hydraulic gradient, tunnelling is neces-sary. Th e general principles of tunnelling are described else-where but for waterworks purposes the tunnels are usually lined,even in rock, partly to ensure that a fall does no t block thewaterway bu t also to reduce the friction. The use of pressuretunnels through the centre of a congested city with moderntunnelling methods is now becoming an economically satisfac-tory alternative to large trunk mains laid near th e surface,provided the strata below the city are satisfactory. London isfortunate in this respect and several trunk aqueducts have beenconstructed in the London Clay.28.3.1 PipesTh e major part of water transmission is through pipes and therehas been a considerable increase in the num bers of new types ofpipes and joints of all sizes in the last few years, including spunand cast iron, ductile iron, steel, concrete, asbestos cement, an dtheir range of joints. The ducts also include unplasticized PV Can d polythene pipes with their corresponding joints. Severaltechnical factors affect the final choice of pipe material, includ-ing internal pressures, hydraulic an d operating conditions,