RAIN WATER HARVESTING: The best method of water conservation is rainwater harvesting, in hills and mountainous region people bult gul/kuls  for agriculture, in Rajasthan rooftop rainwater is harvested or stored for drinking, in Bengal inundations channels are developed for irrigation. In arid or semi-arid places agricultural fields were converted into rain fed storage structures that allowed water to stand and moisten the soil known as KHADINS in Jaisalmer and JOHADS in other parts of Rajasthan. The rainwater is stored in big tanks. Rainwater /Palar pani  is referred to these parts as purest form of water. Now the system of making underground tanks have decline due to INDRA GANDHI CANAL providing perennial water to these area.

INTERSTING FACTS: a) In first century by  Sringavrapura  near Allahabad had sophisticated water harvesting system on river Ganga b) During Chandragupta Maurya many dams lakes etc. were built in KALINGA (Odisha) NAGARJUNKAKONDA (Andhra Pradesh) BENNUR (Karnataka) KOLHAPUR (Maharasthra) c) Bhopal Lake largest artificial lake built in 11 century d) tank in HAUZ KHAS Delhi was constructed by IITUTMISH for supply water Siri fort area. e) Tamil Nadu was the first state in India to make compulsory Top roof rainwater harvesting.

Added: b