Two desalination plants, set up in Minjur in north Chennai and Nemmeli on the East Coast Road, in 2010 and 2013, respectively, have ensured that Chennai gets an assured drinking water supply of 200 million litres a day (more than one-third the total water supply).
This week, the State government inaugurated a third, ₹1,259 crore plant, with a 150 mld capacity, also in Nemmeli. By the end of the year, Chennai Metrowater will float tenders for a fourth plant.
This sounds like a solution. Environmentalists, however, point out that the plants not only consume huge energy, they affect marine life and discharge harmful byproducts. With average annual rainfall of 140 cm, experts argue that Chennai doesn’t need desalination plants, which are more suited to arid areas with limited fresh water.
So what’s a sustainable alternative? Restore existing freshwater sources, say experts. The use of treated sewage is another option. Chennai Metrowater has made some headway here, with a proposal for tertiary plants from where treated sewage will be conveyed to lakes. Reducing over-dependence on fresh water and replenishing the ground water, finally, remain the best bets.