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Water
Rainwater harvestingRebuilding an urban
water cultureShubha Ramachandran
Biome Environmental Trust
The liberator – the hole in the ground which yielded precious
water
Did the Buddha drink from this well ? Sarnath 500 BCE
Vijayanagar Kingdom – 500 years ago
Bangalore – living history (100 years
old)
BANNERGHATTA ROAD
Photo : Norma Angelica Hernandez Bernal
Ultimate source of all water :
RAIN
Local hydrologic cycle
Twin problemsUrban FloodingWater Scarcity
PARADOX ?
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
Rainfall pattern in Tirupur
MONTH QUANTITY (mm)
JAN 14
FEB 6
MAR 13
APR 57
MAY 82
JUN 20
JUL 27
AUG 43
SEP 62
OCT 163
NOV 115
DEC 40
TOTAL 642
How much water can I harvest
How much water do I use ?
Use Litres/person
Drinking 3
Cooking 4
Bathing 20
Flushing 40
Washing-clothes 25
Washing Utensils 20
Gardening 23
Total 135
Real Consumption range :
from 50 to 300 liters per person per day
National Town planning Norms :
Urban : 135 Lpcd
Rural : 55 Lpcd
RWH Potential (for every 100sqm of surface)
Nature of Surface
Runoff Coefficient
Runoff for average 30mm rain (in KL)
Annual runoff for 642mm (in KL)
Rooftop 0.8 2.4 51
Paved Area / Roads
0.5 1.5 32
Unpaved Areas / Garden
0.1 0.3 6
Case: Industry: 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
….So how clean is Rainwater ?....
Rainwater in a Glass
-Guess
Which is which ?
A Bucket of Rainwater
A clean roof means clean water
Downpipes
Down water pipes made of - HDPE- PVC - Chains
Join all the pipes……
Gutters
Gutter-for sloping roof transmitted through- PVC- Polycarbonate- GI
- Aluminium- Stainless steel
PVC GUTTER
Clean Rainwater :FRS & Filtration
First rain separation – let the rain clean the roof
Details of a rain barrel
Aluminium basket filter
Plastic basket filter
Filter
Commercial Filters
Rain barrel : easiest way to begin rainwater harvesting
Rainwater harvesting in an industry
Rain Barrels harvesting rooftop rainwater
Bring it to a Storage
Storing in the Underground Tank
LEVELS !!!!
Ground Water Recharge
● Recharge Well● Deep Borewell Recharge● Recharge Trenches
Groundwater recharge : Wells & Borewells
Wells
`
The pit has reach the silt layer
Pit and concrete rings
Placing of the rings
Recharge Well :The making of a recharge well
Recharge wells details
Silt and leaves trap in a stormwater drainCovers : grilled or perforated RCC
Rainwater sent for recharge
Recharging a bore wellOutlet pipe in recharge well
Schema Front Section - Recharge
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
Borewells !
How does it look inside ?
Recharging directly into borewells
Need to be very very careful About water quality
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
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) !!.
Biome Environmental Solutions Pvt Ltd (Rainwater Club)
[email protected] www.rainwaterclub.org 1022, 1st floor, 6th Block,
HMT Layout, Vidyaranyapura, Bangalore – 560 097,
Phone : 080 41672790
Multi sourcing : Increasing urban reality(Case of Bangalore)
Piped Water : Cauvery River
• Unreliable/erratic ?• Scarcity• Infrastructure growth• Too cheap• 100km from B’lore• 500m below B’lore
Ground Water : Bore/Open well
• Drying up • Bad quality
Ground Water :Tanker Water • Availability ? • Quality ?• Cost ?
Bottled Water•Groundwater ? •Why ? • Is it really necessary or worth it ?
Waste Water Treatment
The product