Rainwater harvesting provides an independent water supply during regional water restrictions, and in developed countries, is often used to supplement the main supply.
It provides water when a drought occurs, can help mitigate flooding of low-lying areas, and reduces demand on wells which may enable groundwater levels to be sustained. It also helps in the availability of potable water, as rainwater is substantially free of salinity and other salts.
Application of rainwater harvesting in urban water system provides a substantial benefit for both water supply and wastewater subsystems by reducing the need for clean water in water distribution system, less generated storm. Rainwater harvesting is one of the simplest and oldest methods of self supply of water for households, having been used in India and other countries for many thousands of years.
Rainwater harvesting systems use the principle of conserving rainwater.
