The rainwater collection for direct use is practised by collection the water coming down from the roof into a storage tank of plastic, R.C.C. or masonry. The tank can be placed either above the ground or below the ground depending on the availability of space and cost consideration cleaning and disinfect the tank at regular interval and raking of filters is most. In a campus whose sufficient space is available, the water can be in an open excavated pond, which also acts as a set point for impurities.
Lets us imagine, that a building having the terrace area of 100sq.m. The average annual rainfall of the area is about 600mm. if there is no loss of water due to seepage due to evaporation all the rainfall on the terrace can be retained. The water on the terrace of the said building would be the height of 600mm.
Area of plot [terrace] = 100sq.m.
Height of the rainwater = 600mm. i.e.0.6m.
The volume of assuming that only 60% of the total water over the terrace is effectively harvested
The total value of water harvesting