CONSERVING WATER one building at a time

Recycling Water Systems Soon To Be Mandatory In All New Constructions

Clara Lewis | TNN

Mumbai: In an attempt to tackle the city’s growing water shortage problem, the Brihanmumbai Municipal Corporation (BMC) is set to pass a proposal making it mandatory for all new buildings to install water recycling systems. Here, grey water (household non-toxic water) is disinfected and then reused for non-potable purposes (see box).

This is to be made a part of the building by-laws, said D L Shinde, deputy municipal commissioner, in-charge of sewage projects. It will be applicable to all building projects where the plot size is 20,000 sq feet and above. The recycling of grey water — which is the norm in the US, the UK and other parts of Europe, Singapore and Australia — has met with success, and the BMC hopes to introduce it in Mumbai.

Besides grey water recycling, the civic body is also planning to make it mandatory for large complexes over 200,000 sq ft to set up sewage water treatment plants. While 20 per cent of the sewage water can be recycled for the complex’s needs, the rest of the treated water will be released into the civic sewerage network. “We are awaiting the election results and will then present the proposals before the standing committee,’’ said Shinde. “The aim is to reduce the burden on the existing sewerage network. Besides, using recycled water will bring down the demand for municipal water. But this will be applicable only to projects where the plot area is two lakh sq feet and above.’’

The cost of setting up the treatment plants will be borne by the builder. “As such big projects are commercial buildings, it makes sense to set up treatment plants. The BMC charges Rs 80 per 1,000 litres for commercial use. If developers set up a treatment plant, the cost can be recovered within two years, and long-term savings will be more, ‘’ said officials.

But in a city where there’s a premium on every sq cm of land, builders remain sceptical. Sunil Mantri of the Maharashtra Chamber of Housing and Industry said, “Such treatment plants are no problem in a large layout and in fact, will be welcomed. But you can’t ignore the fact that space is a big problem. Today, we harvest rainwater as it is mandatory and also useful. Not much space is required to set it up. With grey water plants, the space will have to be exclusive and that can pose a problem.’’

Recycling, however, may be unavoidable, given the city’s water shortage. Besides, recycling water is also a requirement for funds under the Jawaharlal Nehru National Urban Renewal Mission (JNNURM), said Shinde. “With the city’s population increasing by 2.5 per cent annually, the infrastructure and sources of water are inadequate to meet the needs of all its citizens. Even with Gargai and Pinjal, two new sources that have been identified, the water supply will only be augmented by another 1,320 mld,’’ said officials, adding that it will not be enough to meet the city’s needs on a long-term basis.

According to a master plan prepared in 1999 under the chairmanship of Madhav Chitale, by 2021, the city’s population will be 1.65 crore and its water demand would have risen to an alarming 5,400 mld. Mumbai receives approximately 3,450 million litres daily (mld), of which the civic body officially accepts that 680 mld is lost through theft and leakages. Of the 2,770 mld that is distributed, 80% is finally converted into sewage water. The actual water required for drinking and cooking purposes is not more than 45 litres per capita per day. “So, if the non-drinking water requirements are met through recycled water, then more citizens will get drinking water,’’ said civic officials.

The BMC’s track record in implementing such resolutions leaves a lot to be desired, say activists. “Though rainwater harvesting has been made mandatory, there are few success stories,’’ admitted civic officials.

ALTERNATIVE SOLUTIONS

GREY WATER RECYCLING
This is to be implemented in all buildings where the plot size is more than 20,000 sq feet Water from kitchens and bathrooms will be recycled The onus of setting up the system and the plumbing lines rests on the builder A 300 sq ft area must be designated for the recycling tank.

SEWAGE TREATMENT
It will be implemented in all projects (commercial and residential) where the plot size is more than 200,000 sq feet The developer can use 20% of the treated sewage water. 1,000 sq ft of land must be set aside for the treatment plant

A QUESTION OF MONEY
Plots of land over 200,000 sq ft are largely used for commercial purposes such as malls, business centres, etc, where the daily consumption of water is high
A commercial consumer pays Rs 80-80 per 1,000 litres of water, as opposed to residential users who are charged Rs 3.50 per 1,000 litres of water Once the plants are in place, developers will have no need to.

What is GREY WATER?
Grey water, also known as sullage, is non-industrial wastewater generated from domestic usage — bath and kitchen water

It comprises 50-80% of residential wastewater. It does not comprise water sewage or heavily polluted (detergent) water

It gets its name from its cloudy appearance and from its status as being neither fresh nor heavily polluted (black water) purchase water from the BMC

TRACKING THE FLOW
3,450 mld is used in Mumbai 680 mld of water is lost on account of theft and leakages 80% of the remaining 2,270 mld gets converted into sewage water 4,450 mld is the city’s actual need

DAILY USE
Supply perindividual varies from 240 litres per capita per day in high rises to 45 litres per capita per day in the slums

FUTURE IMPERFECT
A 1999 study conducted under the chairmanship of Madhav Chitale, says the city’s population will be 1.65 crore by the year 2021

Demand for water is expected to rise to 5,400 mld

An additional 1,320 mld from two new water sources, Gargai and Pinjal, will be insufficient

SEWAGE WOES: If the proposal is passed, huge complexes will have to set up plants