The ancient irrigation systems of Sri Lanka have been perfected through consistent improvements and construction over 1600 years. Small village cascades are linked up with massive reservoirs in intricate hydraulic systems. Villagers managed the small village tanks (weva), while the large reservoirs were managed and operated by designated families. Collective decisions were taken in a way to accommodate to the high climate variability characteristic of the tropics. The tank irrigation system blends seamlessly to the natural environment, which has been maintained carefully through the preservation of a diverse array of plants and trees that occupy the surrounding land.

During the 20th century, however, poor knowledge of the function of the ancient tank system has lead to its ignorance and destruction by modern large scale irrigation projects, which yet failed to secure reliable water supplies. The restoration and use of the ancient tanks is, therefore, of great importance. What is more, a proper maintenance of old tanks will also help to reduce the malaria epidemic in the region, since abandoned tanks are breeding media for malaria vectors.