In the semi-arid and arid regions of Rajasthan. particularly in Bikaner. Phalodi and Barmer. almost all the houses traditionally had underground tanks or tanks for storing drinking water. The tanks could be as large as a big room; one household in Phalodi had a tank that was 6.1 meters deep. 4.27 meters long and 2.44 meters wide. The tanks were part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard. They were connected to the sloping roofs of the houses through a pipe. Rain falling on the rooftops would travel down the pipe and was stored in these underground tanks. The first spell of rain was usually not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected. The rainwater can be stored in the tanks till the next rainfall making it an extremely reliable source of drinking water when all other sources are dried up. particularly in the summers. Rainwater. or palar pani. as commonly referred to in these parts. is considered the purest form of natural water. Many houses constructed underground rooms adjoining the tanks to beat the summer heat as it would keep the room cool. Rooftop rainwater harvesting is the most common practice in Shillong. Meghalaya. it is interesting because Cherapunjee and Mawsynram situated at a distance of 55 Km. from Shillong receive the highest rainfall in the world. yet the state capital Shillong faces acute shortage of water. Nearly ever household in the city has a rooftop rainwater harvesting structure. Nearly 15-25 per cent of the total water requirement of the household comes from rooftop water harvesting. Today. in western Rajasthan. sadly the practice of rooftop rainwater harvesting is on the decline as plenty of water is available due to the pernnial Indira Gandhi Canal, though some houses still maintain the tanks since they do not like the laste of tap water.Fortunately. in many parts of rural and urban India. rooftop rainwater harvesting is being successfully adapted to store and conserve water in Gendathur, a remote backward village in Mysuru, Karnataka, villagers have installed, in there household's rooftop.