Roof Top Rainwater Harvesting:

In urban areas, the roof top rain water can be conserved and used for recharge of ground water. This approach requires connecting the outlets pipe from roof top to divert the water to either existing well/tube wells/borewells or specially designed wells/ structures. The Urban housing complexes or Institutional buildings have large roof area and can be utilized for harvesting the roop top rain water to recharge aquifer in Urban areas. Table shows the availability of rain water through Roof Top Rain Water Harvesting.

Roof top area (Sq.m)
Rain fall (mm)

100 200 300 400 500 600 800 1000 1200 1400 1600 1800 2000
HARVESTED WATER FROM ROOF TOP (Cum)
20 1.6 3.2 4.8 6.4 8 9.6 12.8 16 19.2 22.4 25.6 28.8 32
30 2.4 4.8 7.2 9.6 12 14.4 19.2 24 28.8 33.6 38.4 43.2 48
40 3.2 6.4 9.6 12.8 16 19.2 25.6 32 38.4 44.8 51.2 57.6 64
50 4 8 12 16 20 24 32 40 48 56 64 72 80
60 4.8 9.6 14.4 19.2 24 28.8 38.4 48 57.6 67.2 76.8 86.4 96
70 5.6 11.2 16.8 22.4 28 33.6 44.8 56 67.2 78.4 89.6 100.8 112
80 6.4 12.8 19.2 25.6 32 38.4 51.2 64 76.8 89.6 102.4 115.2 128
90 7.2 14.4 21.6 28.8 36 43.2 57.6 72 86.4 100.8 115.2 129.6 144
100 8 16 24 32 40 48 64 80 96 112 128 144 160
150 12 24 36 48 60 72 96 120 144 168 192 216 240
200 16 32 48 64 80 96 128 160 192 224 256 288 320
250 20 40 60 80 100 120 160 200 240 280 320 360 400
300 24 48 72 96 120 144 192 240 288 336 384 432 480
400 32 64 96 128 160 192 256 320 384 448 512 576 640
500 40 80 120 160 200 240 320 400 480 560 640 720 800
1000 80 160 240 320 400 480 640 800 960 1120 1280 1440 1600
2000 160 320 480 640 800 960 1280 1600 1920 2240 2560 2880 3200
3000 240 480 720 960 1200 1440 1920 2400 2880 3360 3840 4320 4800