Rainwater Harvesting

Biome Environmental Solutions Pvt Ltd

Also:

PARADOX ?

Water Era in India

• Rainwater + shallow aquifer < 1850

• Surface water + shallow aquifer+ rainwater 1850 - 1970

• Deep aquifer + surface water + rainwater 1970 --2015

• Rainwater + ….+… 2015 >

The liberator – the hole in the ground which yielded precious

water

A hoary past – Well at Lothal 2600 BCE Photo Mrinalinee Vanarase

Did the Buddha drink from this well ? Sarnath 500 BCE

Local hydrologic cycle – seeking bio mimicry with rainwater harvesting

Rainfall pattern in Delhi NCR (varies between NOIDA and GURGAON

30 years data

MONTH DAYS QUANTITY (mm)

JAN 1.2 14.9

FEB 1 13.1

MAR 0.8 8.9

APR 0.5 6.7

MAY 0.8 22

JUN 2.1 44

JUL 7.4 188

AUG 7.9 191

SEP 4.0 94

OCT 0.8 18

NOV 0.1 5

DEC 0.4 5.5

TOTAL 27 611

RWH Potential (for every 100sqm of surface)

Nature of Surface

Runoff Coefficient

Runoff for average 30mm rain (in KL)

Annual runoff for 611mm (in KL)

Rooftop 0.8 2.4 48

Paved Area / Roads

0.5 1.5 30

Unpaved Areas / Garden

0.1 0.3 6

Case: RWH Potential as a % of Annual Demand

● Daily Demand = 15 KL (500 people x 30 lpcd)

● Annual Demand = 5475 KL (15 x 365)

● Total Campus = 3000sqm (~ 30,000sqft)

● Rooftops = 1500 sqm (50% of total area)

● RWH potential from rooftop = 733 KL (1500* 0.8 * 0.611 )

● Other Paved + Unpaved Areas = 1500 sqm

● RWH potential from non rooftops = 275 KL (1500×0.3×0.611)

● RWH Potential as a % of Annual Demand = 18% (733+275)/5475

Rainwater harvesting

components:

1) Catchment

2) Conveyance

3) Filtration

4) Storage

5) Recharge

<<< The saree is the

Catchment, conveyance

And filter !!!!!!

The collection and storage of rain for future productive use

EVERY ROOF CAN BE A CATCHMENT

Gutters

Gutter-for sloping roof transmitted through- PVC- Polycarbonate- GI

- Aluminium- Stainless steel

PVC GUTTER

Downpipes

Down water pipes made of - HDPE- PVC - Chains

Filters

Filters

RWH - Storage

● HDPE tank● Brick Masonry ● RCC tank

Rain barrel : easiest way to begin rainwater harvesting

Rainwater harvesting in an industry

Rain Barrels harvesting rooftop rainwater

Details of a rain barrel

Aluminium basket filter

Plastic basket filter

Storing in the Underground Tank

Ground Water Recharge

● Recharge Well● Deep Borewell Recharge● Recharge Trenches

The pit has reach the silt layer

Pit and concrete rings

Placing of the rings

The making of a recharge well

Procedure • Locate recharge well in the channel or off

the channel

• Make arrangements to remove silt and leaves before water enters recharge well

• Monitor the rate of recharge and decide on the number of recharge wells necessary for the catchment

Don’t forget the maintenance

Recharge pit around bore wells

Planning for RWH

Nature of Surface RWH Strategy

Rooftop Storage or Deep Aquifer Recharge

Paved Area / Roads Shallow Recharge – through trenches, Open Wells

Unpaved Areas / Garden

Shallow Recharge – through trenches, Open Wells

Sizing the RWH Structures

For Storage :

● Depending on usage and budget● Best to use existing storage structures● New storage structures can be sized for 30mm to 60mm rain

For Recharge : ● Calculate runoff for a 25mm-30mm rain and size accordingly

Designing

● Plot Size : 3000sqm

● Rooftop : 1500sqm,

● Non Rooftop : 1500sqm

● Rooftop Storage : 1500 litres filter and 36KL to 72KL storage

OR

● Rooftop Deep Aquifer Recharge :

● Non Rooftop 1500sqm – basic filters in drains and 1 recharge well or 5ft diameter and 30ft deep or Recharge Trench of 20KL capacity

Costs

S No Item Rate

1 4” PVC pipes – with fittings 80/- to 200/- per foot

2 6” PVC pipes – with fittings 280/- to 380/- per foot

3 Brick masonry storage/filter 10/- to 12/- per liter

4 Filter media 5/- to 7/- per liter

5 Commercially available filters - 500sqm

18,000/-

6 4KL Recharge Well 35,000/- to 40,000/-

6 16KL Recharge Well 85,000/- to 1,00,000/-

7 Deep bore with casing 30,000/- to 40,000/- for a 6” bore of upto 30m, 1000/- per meter

8 RCC storage 13/- to 18/- per liter

9 HDPE Storage (Sintex tanks) 6/- to 8/- per liter

10 Labour + Other misc 15% to 20% of material costs

Cramped Spaces

Local organizations/People that can help with the implementation

● CSE : Center for Science and Environment

● FORCE : Forum for Organised Resource Conservation and Enhancement

● R Balaji Engineering Co: GB Road : 011-66361953

● Flowell India, Mayur Vihar

● Geocon Groundwater consultants, Kalkaji (charges for feasibility study and design): 011-66262250

Maintenance

● Keep the terrace/campus clean● Clean Storm water drains● Dont let water stagnate anyplace● Clean out the filters 2 times during the year● Clean the storage tank

Best Practices

● Metering the borewell● Water Balance – Metering Demand

and Supply● Setup Rain Gauge● Metering the harvested rainwater

Monitoring

● Water Quality● Water Availability● Depth to Water (below ground level)● If the water is actually going into the

borehole (rate of recharge) !!.

Existing Success Stories in the neighbourhood

● Hero Moto Corp, Gurgaon● Surya Vihar, Gurgaon● Tex Corp Limited, Gurgaon● BPCL Housing Complex, NOIDA

Biome Environmental Solutions Pvt Ltd (Rainwater Club)

rainwaterclub@gmail.com www.rainwaterclub.org 1022, 1st floor, 6th Block,

HMT Layout, Vidyaranyapura, Bangalore – 560 097,

Phone : 080 41672790