Potential and Limits of Domestic Rooftop Water Harvesting in Una Area of Shiwalik Hills

Water is very scarce resource in Shiwalik hills of Himachal Pradesh. It is very important for the survival of every human being but little attention is being paid for its conservation. Due to indiscriminate use of groundwater the water table is going down abnormally. Rainwater is the main source of water and if rainwater is harvested properly the water shortage problem can be eliminated to a large extent. Rainwater is free from organic matter and soft in nature. It is also bacteriologically pure. This is an ideal solution for a water problem, especially related to hilly areas where the ground water table is low and the surface sources are few and that too are found at a very low elevation in the valleys. The water has to be pumped to a high elevation where the habitations are situated. The rainwater harvested from rooftops can be stored in a tank and can be used directly. It can be used indirectly by diverting it to recharge the aquifer. Though Himachal Government has provided piped drinking water facilities to all of its population in state yet there are areas which face acute shortage of water during dry months. The paper aims toward the development of the framework for domestic rooftop harvesting for household use. The paper is based on the analysis of survey record of 40 houses of different roof areas of Una district in Shiwalik hilly region of Himachal Pradesh in India. The estimation of the appropriate size of the water tanks to fulfill the annual drinking water demand through Domestic Rooftop Harvesting has been done. The domestic rainwater Harvesting (DRWH) has been designed considering the existing rainwater outlets and types of roof prevailing in the area.