Water harvesting is the deliberate collection, concentration and storage of rainwater that runs off a natural or manmade catchment surface. Catchments include rooftops, compounds, rocky surfaces or hill slopes or artificially prepared impervious/semi-impervious land surfaces. Storage is done in tanks, lined pits, small dams or in the sandy of seasonal rivers.
The amount of water harvested (collected and stored) depends on the frequency and intensity of rainfall, the catchments characteristics and water demand and how quickly and how much runoff occurs.
Just like other water resources, rain water harvesting is an option to be considered when planning an improved water supply system with a community. Depending on local environmental conditions, water harvesting may provide a supplementary supply, an alternative suppply or the only feasible improved supply, especially in the rural areas.