S.Vishwanath

www.rainwaterclub.org

Twitter handle : zenrainman

Rainwater harvesting systems

Water Era in India� Rainwater + shallow aquifer < 1850

� Surface water + shallow aquifer+ rainwater 1850 - 1970

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

� Rainwater + ….+… 2015 >

Rainwater harvesting� The method of collecting rainwater from purpose built catchments….. so for example rooftop rainwater harvesting…

Photo courtesy: Shree Padre

� Catchment

� Conveyance

� Filtration

� Storage

Good clean rainwater with a clean catchment and a good filter

The rainwater tank is a great place to do homework

..and is multipurpose , other waters can be stored. Storage is and is multipurpose , other waters can be stored. Storage is and is multipurpose , other waters can be stored. Storage is and is multipurpose , other waters can be stored. Storage is

access in areas of intermittent availabilityaccess in areas of intermittent availabilityaccess in areas of intermittent availabilityaccess in areas of intermittent availability Rooftop Rainwater harvesting is especially relevant in

Fluoride and Arsenic affected areas

� The ‘Sachetana’ project of the Government of Karnataka has put 10000 rainwater tanks in households across 105 villages. This provides drinking and cooking water for the whole year.

� The tank size is between 5000 litres and 8000 litres.

� It provides 20 litres of water per day per family for the whole year.

A ‘Sachetana’ rainwater harvesting system with details

painted on the wall

An above the ground storage tank RWH during Floods

RWH During non-flood situationQuality check- using the H2S strip test for e.coli

identification

Simple treatment using SODIS www.sodis.ch Urban Water and Sanitation

�The urban water footprint is increasing

Cities search for water

�Chennai: 235 km (Veeranam lake) and now planning to go farther 300 Km (Veeranam extension project).

�Bangalore: 95 km (Cauvery) pumping 300 m elevation.

�Delhi: from Tehri dam (450 km)

(Thanks to Gita Kavarana ).

Chennai

Veeranam

lake

Map of Tamil Nadu

Manjira dam

Hyderabad

Nagurjuna

105 km

100 km

Himayat Sagar

Osman Sagar

Vaitarna cum Tansa

90 km

105 km

Mumbai

Bhatsa

Narmada river

70 km

30 km

INDORE

INDORE

YASHWANT SAGAR

Indira Gandh

i canal

204 km

Rajivgandhi lift canal

Jodhpur

JODHPUR

The issue

• Exploding water demand in cities• Problems of urbanization : water shortage and flooding• Need to manage water in cities holistically

• New paradigm required

• Multiple sourcing of water

• Source control for flood management

• Institutional coordination

• People’s participation in solution’s

• More space for ‘softer’ solutions like education

Realities

Water tanker Bore well

With very little catchment management

Water in the city

Lakes and tanks :261 in 196081 in 199755 in 2000

Lake development authority created to preserve and enhance surface water bodies in city

Why harvest rainwater ?

• Provides supplemental water for city

• Recharges groundwater potential lost due to urban ‘crusting’

• Reduce ecological footprint of water (power/water nexus)

• Helps manage urban floods

• Prevents salinity ingress in coastal area

MONTH DAYS QUANTITY (mm)

JAN 0.2 2.70

FEB 0.5 7.20

MAR 0.4 4.40

APR 3.0 46.30

MAY 7.0 119.60

JUN 6.4 80.80

JUL 8.3 110.20

AUG 10.0 137.00

SEP 9.3 194.80

OCT 9.0 180.40

NOV 4.0 64.50

DEC 1.7 22.10

TOTAL 59.8 970.00

Rainfall pattern in Bangalore

30 years data

Local hydrologic cycle – seeking bio mimicry with rainwater harvesting

Hydro-flows� Surface runoff 15 90

� Recharge 10 5

� Evapo-transpiration 75 5

� The aim of rainwater harvesting is bio-mimicry.

Rain barrel : easiest way to begin rainwater harvesting Details of a rain barrel

Aluminium basket filter

Plastic basket filter

.

Rain barrels at work

Rainwater harvesting in an industry

4 acres > objective 0% runoff

Rain Barrels harvesting rooftop rainwater

EVERY ROOF CAN BE A CATCHMENT

The new rainwater harvesting byeThe new rainwater harvesting byeThe new rainwater harvesting byeThe new rainwater harvesting bye----lawlawlawlaw

� By December 31st 2011 …� For every plot create recharge or storage� @ 20 litres per square metre of roof area� @ 10 litres per square metre of paved area

Minimum depth of recharge well 3 metres

About 50,000 buildings now have rainwater harvesting ..another 50,000 expected by year end.

Aerial View of Theme Park•Training for young plumbers

Creating groundwater banks – the use of the aquifer.A good hydro-geological study a prerequisite for artificial recharge using harvested rainwater

The other key objective of rainwater

harvesting is to keep the 500,000

bore-wells with a sunk cost of Rs 5000

crores alive and well

Excavation

The excavation should reach porous soil / weathered rock / fracture.

Digging the pit

Backfilling. Round hard material. Smaller stones on top

Filling of the pit Finished recharge pit

The pit has reach the silt layer

Pit and concrete rings

Placing of the rings

The making of a recharge well

Don’t forget the maintenance

Recharge wells in storm-water drains

Reflective paints but also potable rainwater A flourishing rainwater filter market

And a technology that helps

Reserving 5 % of any space for water

From a plot to the city

A recharge well in an IT office