Rain Water Harvesting and its potential

Rain Water Harvesting is a wonderful science if implemented in depth, as it has the potential to fulfill 50% of Mumbai’s total water requirements. The total demand of Mumbai is about 4000 MLD (million litres per day) whereas the supply is about 3000 MLD. The lack of 1000 MLD is suffered by people living in far-off places like Vasai and Virar just to supply water 24 x 7 to South Mumbai. This is the bitter truth. But the government has taken some steps like making Rain Water Harvesting mandatory for new and upcoming buildings whose plot area exceeds a certain area, without which there would not be any issuance of an O.C (Occupation Certificate). This has definitely given an impetus to Rain water Harvesting Projects. But it has become namesake and many builders do it at that level and thereby at a very low cost to get the O.C. This is not helping the cause of saving BMC Water.

Let us see what Rain Water Harvesting actually is.

RWH is the method of catching the rooftop water and diverting it to the borewells and hence recharging borewells and increasing the groundwater level. This water in general is recharged in sub-soil even in cities like Mumbai. This water of sub-soil can be utilized by others in nearby area too. This is not an exciting fact for any society who intends to do RWH. But we have come up with a very innovative way of RWH. The way which allows users to fulfill all their required quantity apart from primary usage. They get no water bills for secondary water as they themselves use this water from their own borewells. How we do it, is described ahead.

We basically find out water in a given plot using Water finding Survey (using Dowsing, Pendulum method). We drill borewells and check water hardness, contaminaton and pollution at every 10 feet height of the borewell water. At minimum hardness level, we drill horizontally and inclined to make new borewells to find “Water Streams”. Water flows from top to bottom in these streams. We create an infrastructure which holds a large volume of water to create enough weight of water, so that it injects itself into the water streams and gets stored for further usage. Hence the water that is recharged can be utilized only by the organization who have done the RWH project. It is like a bank account wherein we put a total sum of yearly required amount and withdraw as per our requirements on a daily basis.

For example: My building has got 32 flats (A & B wings 4 floors each). The daily requirement of this building is 16,000 litres (500 litres on an average per household). The plot area we have is 200ft x 200ft i.e. total 40,000 sq. ft. Total requirement of this building per year is 16,000*365 = 58,40,000 litres. Approximately 60 lac litres. Rain Water available in the building per rainy season = 40,000 x 3 x 80 = 96,00,000 (96 lacs) (1” rainfall gives 3 litres of water in 1 sq. ft, Mumbai’s rainfall = 80” on average)

The building requires approximately 60 lac liters and RWH has a potential of providing (96 x 2) 1,92,00,000 litres of water. This quantity is double the rain water is because there are underlying water streams. These streams can take in as much water as it can give out. Hence if we have to recharge the water streams with 96 lac litres, there will have to be a source of 96 lac litres beneath the surface and hence double the quantity.

I think with this example one can definitely measure what RWH is capable of.

The elite list of projects which we have done is

1. Sanjay Gandhi National Park

2. Hiranandani Hospital and Buildings

3. Andheri Sports Complex (very challenging one)

4. United Phosphorus (Juhu) (very challenging one)

5. Hyatt Regency, Pune

6. Shri Ram Mills, Worli (54 storeyed building). (The 1^st and the only residential project to have got Platinum Status in the whole world)

7. Neelkanth Valley, Ghatkopar East

8. All staff quarters of Tata Colonies

9. MTNL Staff Quarters

And many more…..

-By Nisarg Shah