RAINWATER AVAILABLE FOR HARVESTING
Total rooftop and surface area: 2,00,916 square metres (sq m)
Average annual rainfall in Delhi: 611 millimetres (mm)
Total volume of rainwater harvested: 48,531 cubic metres (m 3 ) or 4,85,13,149 litres.
Therefore, 39.6 per cent of total rooftop and surface runoff is being harvested.
WATER SUPPLY SOURCE
Private bore wells, coupled with municipal supply.
RAINWATER HARVESTING SYSTEM
Rooftop water from the buildings is discharged into storm water drains, and then it flows along with surface runoff. This water is collected in a collection chamber of size 0.45 m x 0.45 m x 0.5 m which is covered with a perforated slab and placed a low lying area so that water can flow into the collection chamber naturally. Rainwater from this chamber will be diverted to a recharge well measuring 1 m x 1 m x 2 m. This recharge well is provided with a 10 m deep recharge bore of 150 mm diameter. The recharge well is also provided with layers of pebbles and coarse sand to ensure proper filtration of storm water used for recharge.
Implementation of this project was completed in January 2004, and the water level as in January 2005 was around 7.3 m below ground level (bgl).
Cost of the rainwater harvesting system: Rs 1.74 lakh.
2, Nizamuddin East,
New Delhi - 110013