Rainwater Harvesting System at Centre for Science and Environment

May 18, 2016

 

Location: Tughlakabad Institutional Area, New Delhi
Scale: Site level
Implementing organisation: Centre for science and Environment
Average annual rainfall: 611 mm

Total volume of rainwater harvested: 3,66,600 litres
Area: 1,000 sq. m.
Operational since : 1999
Capital cost : Rs. 36,000
O&M: Rs 5,000

 
 

In CSE campus, the rainwater is recharged into the groundwater aquifers with rain water harvesting potential of 6,11,000 Liters. The main objective of this initiative was to demonstrate the implementation of rain water harvesting (RWH) system at an institutional scale to recharge groundwater in the water stressed area.

 
 

TECHNOLOGY & DESIGN

Number of methods are used for harvesting the rainwater so as to ensure that most of the rainwater falling over the building area is recharged.. Following are the type of structures used to recharge:

1. Recharge well with desilting pond: The rainwater drainpipes from all terraces are connected in series so that the runoff from these terraces falls into the pond in the front of the building. When this pond overflows, water flows to the recharge well located in front of building.

2. Soakways: Thirteen soakaways have been constructed around the building. A soakaway is a vertical shaft of 150 mm (6”) diameter bored in the ground to a depth of 30 feet and cased with a PVC pipe. The mouth of the shaft is covered with an inverted earthen pot with a small hole to prevent the entry of debris into the shaft. A small sump is constructed around the top of the shaft, which is filled with a filter media of brickbats to prevent entry of debris. A perforated RCC cover is placed on top of sump to allow the entry of rainfall runoff.

3. Recharge trench: The recharge trench at the entry gate arrests all the runoff from paved area. The water flows according to the natural slope of the site directed to the recharge trench. Three soak ways have been constructed in the trench under the entrance gate, which is covered with an iron grill. The runoff flowing out through the entrance is collected in this trench to recharge ground water through.

4. Abandon well: Rainwater from the rear portion of the terrace is led through a vertical drainpipe to the 45 m deep abandoned borewell

 
 

BENEFITS

The total 3.6 lakh liters of rainwater is harvested annually here, which is equivalent to nearly 70 water storage tanks of 5,000 liters capacity. (Equivalent to 1,000 litres/day). Furthermore, the ground water level is maintained at 65 meters below ground level due to RWH practice. This also saves energy cost for withdrawal of groundwater from deep water table.

 
 

Dr. Suresh Kumar Rohilla
Programme Director, Water Programme, CSE
41, Tughlakabad Institutional Area
New Delhi, India
Email: srohilla@cseindia.org

Ms. Shivali Jainer
Senior Research Associate, Water Programme, CSE
41, Tughlakabad Institutional Area, New Delhi, India
Email: shivali@cseindia.org