How to reuse water, and gain from it

The city’s water crisis is changing the way buildings in Mumbai will be built in future.

The city’s water crisis is changing the way buildings in Mumbai will be built in future.

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The Brihanmumbai Municipal Corporation (BMC) has now made it mandatory for new buildings to set up a grey water recycling plant within the compound to treat and reuse water.

Grey water includes wastewater from the bathroom and kitchen, which is disposed of via the sewer. This water can be recycled in a plant set up in any open space on ground level inside the compound (see box for more on grey water).

Existing and under-construction buildings can also have such plants, with permission from the BMC. In the US, UK, parts of Europe, Singapore and Australia, such plants are the norm.

Last week, the BMC’s improvement committee amended the Development Control rules to allow buildings to set up a treatment

plant in recreational or open spaces inside the society compound, or in the stilt area or basement.

A plant with a capacity of 15,000 litres costs Rs 5-6 lakh and needs about 300 sq ft of space. The cost will have to be borne by the builder.

Apartments that are either built on more than 2,000 sq m, or that contain more than 80 dwellings will have to recycle waste water to use for non-potable purposes like cleaning, washing cars, gardening and in toilets.

According to the new by-laws, apartments consuming over 60,000 litres daily will have to set up such plants compulsorily.

The BMC has proposed a 25 per cent rebate in water and sewerage tax for those who follow the rules.

“We have made it compulsory only for new structures, they will be given the occupation certificate only if they follow this rule.

Existing building societies interested in setting up recycling plants can submit their plans to us,” said Ashok Shintre, chief engineer, Building Proposals department.

Such plants need regular maintenance. “We’ve seen that over the years, a plant becomes non-functional as building societies don’t bother getting them looked at from time to time,” said Sriniwas Bhambore, CEO of Aquachem Systems, which has set up such plants in housing societies in the city.