Rainwater harvesting Concept and Principles

1. Water
Rainwater harvesting
Concept and Principles
Shubha Ramachandran
Biome Environmental Trust

2. Rainwater
harvesting
components:
1) Catchment
2) Conveyance
3) Filtration
4) Storage
5) Recharge
<<< The saree is the
Catchment,
conveyance
The collection and storage of rain for future productive
use

3. Rainfall pattern near Tirupur (Tamilnadu)
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

4. Rainfall pattern in Anekal (in Karnataka)
MONTH QUANTITY (mm)
JAN 5.3
FEB 6.3
MAR 8.8
APR 42.2
MAY 118.6
JUN 60.7
JUL 91.3
AUG 116.7
SEP 140.8
OCT 156
NOV 65.4
DEC 15.9
TOTAL 828

5. Rainfall pattern near Mumbai (Maharashtra)
MONTH QUANTITY (mm)
JAN 0.6
FEB 1.5
MAR 0.1
APR 0.6
MAY 13.2
JUN 574.1
JUL 868.3
AUG 553
SEP 306.4
OCT 62.9
NOV 14.9
DEC 5.6
TOTAL 2401

6. 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

7. How much water can I harvest

8. 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

9. Case: Home with 6 members + 2 cows (near Anekal)
● Daily Demand =
● Annual Demand =
● Plot size = 2 acre
● Rooftops =
● RWH potential from rooftop =
● Other Paved + Unpaved Areas =
● RWH potential from non rooftops =
● RWH Potential as a % of Annual Demand =

10. ….So how clean is Rainwater ?....
Rainwater in a Glass
-
Guess
Which is which ?
A Bucket of Rainwater

11. A clean roof means clean water

13. Join all the pipes……

14. Gutters
Gutter-for sloping roof transmitted through
- PVC
- Polycarbonate
- GI
- Aluminium
- Stainless steel
PVC GUTTER

16. Clean Rainwater :FRS & Filtration

17. First rain separation – let the rain clean the roof

18. Details of a rain barrel
Aluminium basket filter
Plastic basket filter

19. Filter

21. Commercial Filters

23. Rain barrel : easiest way to begin rainwater harvesting

24. Rainwater harvesting in an industry
Rain Barrels harvesting rooftop rainwater

25. Bring it to a Storage

26. Storing in the Underground Tank

29. LEVELS !!!!

30. Ground Water Recharge
● Recharge Well
● Deep Borewell Recharge
● Recharge Trenches

31. Groundwater recharge : Wells & Borewells

32. Wells
`

33. The pit has reach the silt layer
Pit and concrete rings
Placing of the rings
Recharge Well :The making of a recharge well

34. Recharge wells details
Silt and leaves trap in a stormwater drain
Covers : grilled or
perforated RCC

35. Rainwater sent for recharge
Recharging a bore well
Outlet pipe in recharge well

36. Schema Front Section - Recharge

40. 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

41. Don’t forget the maintenance

43. Borewells !
Howdoesitlookinside?

44. Recharging directly into borewells
Need to be very very careful
About water quality

46. 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

47. 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

53. SOLAR
DISINFECTION

58. 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

59. Best Practices
● Metering the borewell
● Water Balance – Metering Demand and Supply
● Setup Rain Gauge
● Metering the harvested rainwater

61. Monitoring
● Water Quality
● Water Availability
● Depth to Water (below ground level)
● If the water is actually going into the borehole (rate of recharge) !!.

62. 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