11. 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
12. 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
13. 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
14. 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
29. The pit has reach the silt layer
Pit and concrete rings
Placing of the rings
The making of a recharge
well
30.
31. 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
35. 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
36. 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
37. 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
38. 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
40. 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
41. 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
42. Best Practices
● Metering the borewell
● Water Balance – Metering Demand
and Supply
● Setup Rain Gauge
● Metering the harvested rainwater
43.
44. Monitoring
● Water Quality
● Water Availability
● Depth to Water (below ground level)
● If the water is actually going into the
borehole (rate of recharge) !!.
