Area of the Building 2000 sq.m. Average Annual Rainfall 1000 mm (or) 1 m. Expected quantity of water 20 lakh litres Rain water available for harvesting 12 lakh litres Requirement for TWAD Head Office: No.of Staff 1000 persons Lpcd required 10 litres Therefore total requirement 10000 Lit./day Requirement per year 30 lakh litres
The rain water harvest will meet out 50% requirement of TWAD House besides there is also a possibility of recharge from the storm water collected in the open area.

TWAD Board has practised rainwater harvesting techniques to conserve
water and use it for its office- use purposes through
3 nos. of recharge bore well trenches &
1 no.of recharge well to augment the existing source.
The total cost of construction of these structures is Rs.1.35 lakhs.

RAINWATER COLLECTED IN THE ROOF IS HARVESTED THROUGH 3 NUMBERS OF RECHARGE TRENCHES WITH BOREHOLES AND 1 NUMBER OF RECHARGE WELL.

TRANSVERSE SECTION OF RECHARGE TRENCH- DETAILS

150 mm DIA BOREWELL IS DRILLED FROM THE BOTTOM OF THE TRENCH AND THIS UNLINED BOREWELL IS FILLED WITH PEBBLES OUT OF THE 2 M DEPTH, THE BOTTOM 0.7 M IS FILLED WITH GRADED PEBBLES AND THE BALANCE 1.3M IS FILLED WITH SAND

Recharge well diameter 1.2 m. Depth 4. 0 m Unlined borewell inside the well 2.0 m packed with pebbles. Outer pit diameter 2.0 m packed with sand followed by pebble.

Water supply to TWAD House is provided from the METRO watersupply and at the rate of RS.9906/month. Up to November 1999. From November 1999 to 12.1.2000 water is obtained from Metro water through lorries at the rate of RS.450/load of water. From 13.1.2000 water is pumped from the shallow borewell constructed near the sump at a cost of RS.5500/-. Capacity of the sump is 54,000 litres Presently the water supply requirements of the TWAD House is being met with from this shallow borewell. The Rainwater Harvesting structures constructed in TWAD House is likely to enhance potentially of the shallow aquifers.

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