  rainwater harvesting is the accumulation and deposition of rainwater for reuse on-site, rather than allowing it to runoff. uses include water for garden, water for livestock, water for irrigation, water for domestic use with proper treatment, and indoor heating for houses etc. in many places the water collected is just redirected to a deep pit with percolation. the harvested water can be used as drinking water as well as for storage and other purpose like irrigation. ==advantages== rainwater harvesting provides an independent water supply during regional water restrictions and in developed countries is often used to supplement the main supply. it provides water when there is a drought, can help mitigate flooding of low-lying areas, and reduces demand on wells which may enable ground water levels to be sustained. it also helps in the availability of potable water as rainwater is substantially free of salinity and other salts. ==quality== the concentration of contaminants is reduced significantly by diverting the initial flow of run-off water to waste.new scientist, 3 april 1999 improved water quality can also be obtained by using a floating draw-off mechanism (rather than from the base of the tank) and by using a series of tanks, with draw from the last in series. the stored rainwater may need to be analyzed properly before use in a way appropriate to ensure its safe use. the quality of collected rainwater is generally better than that of surface water. contamination is always possible by airborne dust and mists, bird feces, and other debris, so some treatment may be necessary, depending on how the water will be used. ==system setup== rainwater harvesting systems can be installed with minimal skills. the system should be sized to meet the water demand throughout the dry season since it must be big enough to support daily water consumption. specifically, the rainfall capturing area such as a building roof must be large enough to maintain adequate flow. the water storage tank size should be large enough to contain the captured water. ==rain water harvesting by freshwater flooded forests==  rain water harvesting is possible by growing fresh water flooded forests without losing the income from the used /submerged land.rain water harvesting by fresh water flooded forests the main purpose of the rain w
Appropriate_technology Aquifers DIY_culture Hydrology_and_urban_planning Irrigation Water_conservation Water_supply