Rooftop rainwater harvesting involves taking down a PVC or M.S. pipe of 90-120mm. die from the roofs outlet to the ground floor, which can be collected to a water [placed either above the ground level or below be ground level] or to the underground water table. The rainwater before collection should however generally be passed through simple sand or charcoal filters for the removal of suspended particles and microorganisms from the rain run being collected. The roofs or courtyards should also be kept as clean as possible at the time of rain.
When rainwater collection for direct use is difficult or costly or impracticable, then groundwater recharge option can be easily be practice to supplement the falling groundwater to infiltrate into the ground to join the water table either through a recharge pit or through a recharge well or through a recharge well with a pressure flit er, depending upon the available circumstances.