Rain water harvesting is being increasingly used all over Kerala. The increasing population and residences have increased the demand for water. Maximum utilization of water calls for the use of rain water harvesting. Kochi flats
are increasingly emphasizing the use of rain water harvesting system.
Rain water harvesting is capturing rain where it falls or capturing the run off. It is necessary to keep the water clean by not allowing polluting activities in or around the catchment. Water harvesting can be undertaken through a number of ways like capturing runoff from rooftops, local catchments, seasonal floodwaters from local streams and conserving water through watershed management. The water thus saved can be used for drinking, irrigation water, increasing groundwater recharge, reducing storm water discharges, urban floods and overloading of sewage treatment plants, reducing seawater ingress in coastal areas. It is the activity of direct collection of rainwater. The total amount of water that is obtained in the form of rainfall over an area is called the rain water endowment of the area. Rain is the first form of water in the hydrological cycle and serves as a primary source of water. Rivers, lakes and ground water are secondary sources of water.
A far-reaching network, known as the National Water Harvesterís Network (NWHN), addresses water issues through people from diverse background in India and abroad. Professionals, bureaucrats, grassroots functionaries, interested citizens and those committed in developing or undertaking water harvesting program constitute the members of NWHN. The local issues and the traditional systems relating to water harvesting is addressed and highlighted by the network. They thus help in promoting the cause of community based water management.