Rainwater harvesting is the accumulation and deposition of rainwater for reuse on-site, rather than allowing it to run off. Its uses include water for garden, water for livestock, water for irrigation, water for domestic use with proper treatment, and indoor heating for houses etc.
Rainwater Harvesting and Conservation is the activity of direct collection of rain water. The conservation of rain water so collected can be stored for direct use or can be re-charged into the ground water. The main goal is to minimize flow of rain water through drains / nallahs to the rivers without making any use of the same.
It is a known fact that ground water level is depleting and going down and down in the last decades. Thus Rainwater Harvesting and Conservation aims at optimum utilization of the natural resource that is rain water, which is the first form of water we know in the hydrological cycle and hence is a primary source of water for us. The rivers, lakes and ground water are secondary sources of water. In present time, in absence of Rainwater Harvesting and Conservation, we depend entirely on such secondary sources of water and in the process it is forgotten that rain is the ultimate source that feeds to these secondary sources. The value of this important primary source of water must not be lost. Rainwater Harvesting and Conservation means to understand the value of rain and to make optimum use of rain water at the place where it falls.
Why to harvest rain?
- In areas where there is inadequate groundwater supply or surface resources are either lacking or insufficient, rainwater harvesting offers an ideal solution.
- Helps in utilising the primary source of water and prevent the runoff from going into sewer or storm drains, thereby reducing the load on treatment plants
- Reduces urban flooding
- Recharging water into the aquifers help in improving the quality of existing groundwater through dilution.
The artificial recharge to ground water is a process by which the ground water reservoir is augmented at a rate exceeding that obtained under natural conditions of replenishment.
The basic purpose of artificial recharge of ground water is to restore supplies from aquifers depleted due to excessive ground water development. There are two main techniques of rainwater harvesting:
- Storage of rainwater on surface for future use
- Recharge ground water
Rainwater Harvesting from roofs consists of collecting, storing, and putting to use rooftop rainwater from houses or any construction is Rooftop Rainwater Harvesting.
Rainwater Harvesting can also be collecting, filtering and recharging ground water through percolation pits, open wells or bore wells.