Fifty shades of greywater

In a city without a perennial source of water, we often look to the skies in nail-biting anticipation of water needs being fulfilled. With rapid urbanisation, the city is moving towards a state of water stress, where demand will soon overtake availability. It’s time now, to expand the horizon of water conservation by taking it towards recycling and reuse.

In 2003, when Chennai was reeling under a severe water crisis and tankers were criss-crossing streets round the clock, a resident of Guindy told me about his water-saving methods. He bathed standing in a large tub that collected water, and then used it to flush. This may be difficult to believe now. But when a pot of water was considered as precious as a pot of gold, this was an innovative idea for many.

Chennai consumes about 830 million litres of water a day (mld), and generates a sewage load of 470 mld. While Chennai Metrowater is trying to add more facilities to deal with its struggle to treat sewage before releasing it into waterways and introduce tertiary treatment to serve industrial needs, more initiatives are necessary to reduce the burden on freshwater sources and to mitigate pollution.

The practice of harnessing rainwater gained focus a decade ago when it was made mandatory. It is said that greywater (waste water generated from domestic activities) contributes to nearly 60 per cent of the sewage load, and by reusing it much of the burden on the sewerage network could be reduced. While some apartment complexes have facilities to treat sewage, a few have adopted traditional methods of filtering and reusing greywater, using a canna plant bed. However, the concept has not caught on in the city.

At a time when the State government is looking at the possibility of making greywater recycling mandatory, it could incorporate a few features of waste water management plans adopted in other cities.

Many cities present role models on waste water management that could be emulated. Jamshedpur for instance, incorporates sewerage services costs in the overall metered water usage charges.

In its attempt to become self-sufficient, Singapore, a leader in water management, has pursued the purification of wastewater, branded ‘NEWater’. While most of it goes for industrial use, a small percentage is fed into the reservoirs and treated again before being supplied to consumers. Officers who are part of the Public Utilities Board, Singapore, told me that nearly 30 per cent of water needs is met through this.

NEWater is distributed to people in bottles at government offices and and I found it tasted exactly like packaged drinking water. While this concept might need a change in people’s mindsets in Chennai, the government could start by making greywater recycling mandatory in commercial and residential buildings. It is also necessary to identify a monitoring agency to sustain the system and create awareness about the significance of the three Rs – reduce, reuse, recycle.