Many individuals / societies wish to know the quantum of rain water that can be harvested. As it it is not easy to visualise how much rainwater thet can actually save.
The following illustration will help you understand the amount of rainwater that can be saved in a city like mumbai. Please note that the average consumption for bathing, cleaning & flushing needs per family per day in Mumbai is 300 litres (as per BMC estimates). A society with 20 households then would ideally need 6000 litres per day,
The amount of water that can be harvested depends upon the rainfall in the area, the size of the catchment area & the percentage of rain that can be collected.
Suppose the system has to be designed for a building with a rooftop area of 100 sq. m.
Area of the catchment = 100 sq. M.
Avg Mumbai annual rainfall = 2400 mm (2.4 m)
Runoff coefficient (% of water that can be potentially harvested) 0.85
Annual water harvesting potential for this building will be
100 x 2.4 x 0.85 i.e. 204 cu. m.
This is 2,04,000 litres approx.
This would meet the needs of the above mentioned society for at least a month in case there are water cuts.
You can imagine the savings a society would ahve in case they would need to source the same through water tankets which cost from 500-600 Rs. subject to availabilty.
In case you would like to know more on how rainwater harvesting can benefit you please feel free to cal me on 99200 23559 or visit my website www.dndecotech.com