Rain Water Harvesting

By Murari Chaturvedi

India gets ample rains but unfortunately there are no proper efforts made by the builders for it. Rain water harvesting gas been used from centuries in India. ‘Johads’ are in use historically in Rajasthan to store rain water. Johads are underground storage facilities and also above ground tanks in most of the forts and ancient buildings in water starved Rajasthan. The tremendous increase in population in all urban areas in the country has put starins on water supply. Clean water to the citizens is must to avoid several diseases. In Mumbai the municipal corporation has made it compulsory to harvest rain water in new constructions. In fact the municipal authorities should pass rules for all buildings old and new to create rain water harvesting system. In Chennai they could solve their acute water problem by rain water harvesting to a great extent. So, why we cannot replicate to construct this system all over India? The system is simple and can be made with local labor and materials. There are two methods of water harvesting which we receive from the rains, namely Rain water Harvesting and Recharging the wells and aquifirs. In the first method there are four elements viz. Catchment area, conduits settlement tank and storage facility. The first, catchment areas in cities are terraces slopping sheds etc. where the runoff water is 70to 80 per cent as most of the water is available for storage. The terrace or sheds must be cleared properly. The conduits or the pipes carry water from the catchment areas or roof tops to storage system. The pipes may be of PVC, asbestos, galvanised pipes or even bamboos. These tanks are basically used to remove the slit and other floating impurities. The tank is ordinary container having provisions for inflow from terrace and outflow to recharge storage facilities and also acts like buffer in system to store the water from rainfall. Bottom layer of the settlement can be filled with filter media of sand and gravel. This filter media is to be removed and cleaned after every 2-3 years. From settling tank the water goes to storage tank through pipes connected to it from the settling tank. Another method is to recharge the wells and aquifirs. When the bore well is used then the casing outer pipe of bore well should be perforated so that more surface area is available for rain water to percolate storage. Rain water for direct use can be done by storing the roof water in underground RCC tanks or above ground PVC/ HDPE tanks for use in dry days rainwater harvesting has proved to be very effective all over the world.

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