Rainwater harvesting is a technique of collecting and storing rainwater for future use. It is a traditional method of storing rain water in underground tanks, ponds, lakes, check dams and used in future.
The main purpose of rainwater harvesting is to make the rainwater percolate under the ground so as to recharge ‘groundwater level’.
(i) Roof top rainwater harvesting: Roof-tops are excellent rain catchers. The rain water that falls on the roof of the houses, apartments, commercial buildings etc. is collected and stored in the surface tank and can be used for domestic purpose.
(ii) Recharge pit: In this method, the rainwater is first collected from the roof tops or open spaces and is directed into the percolation pits through pipes for filtration. After filtration the rainwater enters the recharge pits or ground wells.
People living in rural areas adopt a variety of water collecting methods to capture and store as rain water. Some of the methods used are
(i) Digging of tanks or lakes (Eris): It is one of the traditional water harvesting system in Tamil Nadu. Eris are constructed in such a way that if the water in one eri overflows, it automatically gets diverted to the eri of the next village, as these eris are interconnected.
(ii) Ooranis: These are small ponds to collect rainwater. The water is used for various domestic purposes (drinking, washing and bathing). These ponds cater the nearby villages.
Rainwater harvesting helps to
i. Overcome the rapid depletion of ground water levels.
ii. To Meet the increase demand of water.
iii. Reduces flood and soil erosion
iv. Water stored in ground is not contaminated by human and animal wastes and hence can be used for drinking purpose.