Recharge pits and shafts in open land
Parks, campuses, warehouse yards and road sides can take recharge shafts that reach past the clay layer, so runoff that floods streets goes down to the aquifer instead.
Put back what we pump out
Groundwater falls when more is pumped out than rain puts back. There are only two levers: recharge more and use less. Most districts need both, and the right mix depends on who uses the water.
Ways to recharge and save
Rooftop rainwater recharge
Pipe roof water through a silt trap and filter into a recharge pit or an old borewell. Every 100 m² of roof puts back tens of thousands of litres a year, right where the pumping happens.
Revive village ponds and johads
Desilting old ponds and opening their feeder channels restores natural recharge. A one-hectare pond that soaks in a metre of water over the monsoon puts back about a crore litres.
Treat and reuse wastewater
Treated water from a sewage treatment plant can run flushing, gardens, cooling towers and construction, which today often draw on borewells.
Check dams and contour trenches
On sloping or rocky land, small dams on seasonal streams and trenches along contours slow water down long enough for it to sink in.
Meter borewells and fix leaks
Metered and registered borewells, leak repairs in supply lines and water-efficient fixtures cut pumping without anyone going short.
Switch thirsty crops, water by drip
Where most water goes to fields, moving from paddy and sugarcane to millets, pulses or maize, and from flood to drip or sprinkler irrigation, saves more than any recharge can add.
Permeable paving and green cover
Porous pavers, unpaved tree pits and bioswales along roads let rain soak in instead of racing to the drain.
How a rooftop recharge system works
Catch
Collect rain from roofs and paved areas through gutters and down pipes.
Clean
Pass it through a silt trap and a filter of gravel, sand and charcoal, after letting the first dirty flush run off.
Recharge
Lead it into a recharge pit, trench or an unused borewell that reaches the water-bearing layer.
Maintain
Clean silt traps and filter media before each monsoon so the pit keeps taking water.
Work out your own building
Your building: how much can you recharge?
Water you can put back each year≈ 12 water tankers of 10,000 L
1 mm of rain on 1 m² is 1 litre. The surface factor allows for water lost to splash, evaporation and first-flush.
Not sure of your rainfall? Look up your district: each page shows 20 years of rain and fills this in for you.
Want a recharge plan for your site?
TerraSetu designs and builds rainwater harvesting and recharge systems for homes, housing societies, schools, factories and warehouses, and inspects and repairs existing pits.