When it rains, they run into the pump house

T  his monsoon, there was something fishy going on at the rundown pumproom of Avanti Niketan, a housing society in Sion. A bunch of society members were often spotted spending days walking in and out of the dingy place, some even sneaked in at midnight to check the motors, while others rushed to the water tank on rainy days with unwarranted excitement, a large bamboo stick in tow.

This motley group of eight — six businessmen, one engineer and a professional — have been on a mission to harvest as much rainwater as possible during the monsoon for the last two years.

Work on the rainwater harvesting (RWH) project started back in 2007 when some sections of the pipelines that carried the BMC’s water were changed because of rusting. After the new pipes were installed, the society was left with the debris of old pipes, some of which were still in good working condition. “We decided to put them to use,” says committee member Gaurang Damani. The rainwater harvesting project was his brainchild.

These pipes were used to channelise the water that gets collected on the building terrace during the monsoon, to an existing well in the society. “However, since large parts of the Sion-Matunga area used to consist of salt pans and is also close to the creek, the salt content in the well was high. As a result, the water we channelised into the well got contaminated and wasn’t fit for use. This year we decided to channelise the water collected on the terrace to an underground water storage tank of the society which is separate from the drinking water tank,” explains Damani. 

The team did rigorous research and planning on the subject before implementing the rainwater harvesting system. They also decided to set up the system themselves without approaching consultants who help set up such systems. It wasn’t an easy task though. The team had to overcome a lot of difficulties — polyvinyl chloride  (PVC) pipes cracked due to pressure and pipes got blocked due to dirt collection. “None of us have a background on setting up a RWH system. We turned to the internet for all our information and learned from a continuous trial and error process,” says Nirav Shah, secretary of the housing society.

“In theory, Avanti Niketan can collect about 8-10 lakh litres of pure rainwater from its terrace in the entire monsoon season. The society on the whole requires 2 lakh litres of water on a daily basis. This monsoon, the rainwater has covered about three per cent of our total water usage during these four months,” explains Damani.

For the past four months, the rainwater has been used in the domestic workers’ toilets, for the cleaning of the swimming pool and building tiles and washing over 170 cars owned by society residents daily. The total expenditure on the project has been a little above Rs1 lakh. “Companies that offer rainwater harvesting models charge close to Rs7 lakh per project. Our project is far more reasonable in terms of costs,” insists Damani.

However, this was merely the first phase of the project. “Next year the society plans to capture rainwater from the entire plot and not just the building terrace. Our estimates show that we should be able to collect around 1crore litres during the monsoon. If we succeed, then the water will last us for the entire year,” adds Damani.