- Many thought that given the disadvantages and rising resistance against the multi-purpose projects , the water harvesting system was a viable alternative , both socio-economically and environmentally .
- In ancient India , along with the sophisticated hydraulic structures , there existed an extraordinary tradition of water-harvesting systems .
- People had in-depth knowledge of rainfall regimes and soil types and developed wide ranging techniques to harvest rainwater , groundwater , river water and flood water in keeping with the local ecological conditions and their water needs .
- In hill and mountainous regions , people built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture.
- ‘Rooftop rainwater harvesting’ was commonly practiced to store drinking water , particularly in Rajasthan .
- In the flood plains of Bengal , people developed inundation channels to irrigate their fields .
- In arid and semi-arid regions , agriculture fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil like the ‘khadins’ in Jaisalmer and ‘Johads’ in other parts of Rajasthan .
- In the semi-arid and arid regions of Rajasthan , particularly in Bikaner , Phalodi and Barmer , almost all the houses traditionally had underground tanks or tankas 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 metres deep , 4.27 metres long and 2.44 metres wide .
- The Tankas 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 ‘tankas’ .
- 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 tankas 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 ‘tanka’ to beat the summer heat as it would keep the room cool .
- 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 their households, a rooftop rainwater harvesting system to meet their water needs .
- Nearly 200 households have installed this system and the village has earned the rare distinction of being rich in rainwater .
- Gendathur receives an annual precipitation of 1,000 mm , and with 80 percent of collection efficiently and of about 10 fillings , every house can collect and use about 50,000 litres of water annually .
- From the 200 houses , the net amount of rainwater harvested annually amounts to 1,00,000 litres .
