Rainwater harvesting is mainly done for two reasons – one, to store the water for later use, and two, to recharge the ground.
One of the simplest methods of harvesting rainwater is to divert the rain that falls on the terrace into open wells.
In the absence of an open well, a percolation/recharge well could be dug within the premises to inject rooftop water into it for groundwater recharge. A recharge well usually is around 10-15 feet deep. The depth of these baby wells usually depend upon the nature of the soil underneath and the volume of water the recharge well is expected to receive during downpours.
The downtake pipe carrying rainwater from the rooftop is connected to these recharge wells. Care should be taken to not fill it up with debris or gravel. These wells should be left unfilled and covered with concrete slabs of suitable thickness to aid in vehicular movement inside the building.
More info: IndiaWaterPortal
Produced by: Sekhar Raghavan, IndiaWaterPortal
Region: India, South Asia