More buildings to adopt rainwater harvesting

In a bid to bring majority of the areas of the city under rainwater harvesting (RWH), the Brihanmumbai Municipal Corporation’s (BMC) Development Plan 2034 has reduced the plot size limit for mandatory implementation of RWH.

RWH will now be mandatory for all plots not less than 500 square metres in size as per the new draft DP, in comparison to the 1,000 square meters mandatory according to DP 1991. However, this provision is in contrast to an earlier provision of 2007, where the BMC had made it mandatory for new buildings on plots above 300 square metres to install rainwater harvesting systems.

Ramnath Jha, officer on special deputation for the DP, said, “The nature of development in Mumbai is such that smaller plots form a significant per cent of the city’s area. If they take up rain water harvesting, we will be able to meet the water demands of the city.”

Such plots can opt for the provision of setting up rainwater harvesting units either on rooftops or in the available open spaces within their compounds.

With this proposal, the civic body expects that it will be able to harvest up to 590 million litres per day of rainwater, out of the 2,000 millimetres of rainfall that the city receives annually.

This is on the basis of the assumption that up to 50 per cent of roof top surfaces, terraces, and balconies can be utilised for harvesting up to 70 per cent of the rain water, amounting to 590 ml per day.