Royal Bhutanese Embassy's Rainwater Harvesting System

RAINWATER AVAILABLE FOR HARVESTING

Total rooftop and surface area: 31,363 square metres (sq m)

Average annual rainfall in Delhi: 611 millimetres (mm)

Total volume of rainwater harvested: 7,867 cubic metres (m 3 ) 78,67,000 litres

Therefore, 26 per cent of total rooftop and surface runoff is being harvested.

WATER SUPPLY SOURCE
Two privately owned bore wells in the campus, coupled with MCD supply. On an
average 25,000 litres of water is consumed daily for potable and non-potable
purposes.

RAINWATER HARVESTING SYSTEM
Rooftop rainwater harvesting: Rooftop rainwater from all buildings in the
Embassy directly flows to the ground as these have sloping roofs. The rainwater flowing in a network of storm water drains is intercepted at strategic locations and diverted into recharge wells that are located near officers' quarters, entrance gate and near the Ambassador's bungalow. The recharge wells are 2 m x 2 m x 2 m in size and are provided with a recharge bore of 150 mm diameter and 15 m depth to facilitate recharge. Layers of boulders, pebbles and coarse sand in the recharge will ensure efficient filtration.

The rainwater from staff residence and officers' quarters flowing in
drains is used for recharge through percolation pits. The pits are
0.7 m x 0.7 m x 1 m in size and are provided with recharge
bores of 150 mm dia and 12 m depth. The pits are also filled up with layers of pebbles

Surface runoff harvesting:
The surface runoff behind the Ambassador's residence is captured in a recharge well by means of a trench, filled up with pebbles to arrest the silt and other suspended particles. The recharge well is 2 m x2 mx2 m in size and provided with a recharge bore of 150 mm dia and 15 m depth to facilitate recharge.

Dry well recharging: The rooftop rainwater and surface runoff generated near the Chancery building is flown into storm drains. This water is diverted into
desilting chamber of size 2 m x 2 m x 2 m. The suspended particles settle here because the velocity of water is checked. The filtered water is finally diverted into a dried open well near the entrance gate.

Implementation of this project was completed in June 2004, and the groundwater level as in January 2005 was 18.8 m below ground level (bgl).

Cost of the rainwater harvesting system: Rs 1.10 lakh