Bandra college collects 4 lakh litres of rainwater
across 140 and 400 sq metres, as catchment area. The terrace has drains, ‘V’-shaped parapets that collect rainwater and guide it to pipelines, and ‘U’-shaped pipe channel that further navigate it to a storage tank of 10,000-litre capacity. As of now, two laboratories are functioning on rainwater harvested this season.
Varsha Shah, principal, Rizvi College of Engineering said, “Rainfall of about 50-60mm feeds the tank to its fullest capacity in half an hour. The collected water is utilised in laboratories of civil and mechanical engineering such as applied hydraulics, fluid mechanics and internal combustion engine. It is also used for plantations on the one-andhalf acre campus, and for developing a green wall planted by the institute.”
The faculty plans to ultimately convert all seven rooftops to catchment areas. “Such a system can be easily designed and implemented if designed properly as per the availability of space. Our aim is to reduce our dependency on Brihanmumbai Municipal Corporation’s (BMC) water supply completely over the next year,” said Shah. Domestic users currently spend about ₹5.09 per 1000 litres on BMC water. “An organised, broader, strategic plan to implement rainwater harvesting across much larger areas within Mumbai needs to be done through policy measures rather than making it compulsory for individual societies,” said hydrogeologist Himanshu Kulkarni, director, Advanced Centre for Water Resources Development and Management. According to a civic official, BMC had in 2002 made it mandatory for new buildings to install their own rainwater harvesting systems, but just over a third of the buildings complied with the rule. BMC supplies 3,800 million liters per day (MLD) of water to the city, against the requirement of 4,200 MLD.
“There was a law that said after 2007, any builder who constructs a new building should include rainwater harvesting plants in the plan. However, there is no check on their design, thus rendering them inadequate,” said Janak Daftari, convener, Jal Biradari and water conservationist.
So far, Mumbai has recorded 1,866mm rain – 88% of the season’s rainfall average – in one and half months.