An
irrigation tank or
tank is an artificial
reservoir of any size, mainly in
India. (The word
sagar refers to a large lake, usually man-made). It can also have a natural or man-made spring included as part of a structure. Tanks are part of an ancient tradition of harvesting and preserving the local rainfall and water from streams and rivers for later use, primarily for agriculture and drinking water, but also for sacred bathing and ritual. Often a tank was constructed across a slope so to collect and store water by taking advantage of local mounds and depressions. Tank use is especially critical in parts of
South India without
perennial rainfall where water supply replenishment is dependent on a cycle of dry seasons alternating with monsoon seasons.