Madhumitha Viswanath By Express News Service CHENNAI: At a time when both the city and state are facing a severe drought, the unavailability of water and rigorous search for alternative sources is looming large. The continued crisis shows no sign of abating despite desperate measures by its residents. But amid this distress what has been underestimated is the mammoth loss of water during transmission to the consumer. About 40 per cent of water distributed by Chennai Metro Water to the city is lost just during delivery. Even a country like Germany, which is far superior than India when it comes to water supply, loses 17 per cent of its total supply during transportation. The only way to keep this number at a bare minimum while ensuring even distribution is to shift towards a decentralised system of water supply, say experts and officials. The flipside Chennai has a defined water system. Only three water treatment plants function to supply 830 MLD during non-drought periods and 500 MLD or less during drought. Two reservoirs of Chembarambakkam and Red Hills have one plant each and there is one at Kilpauk built by the British before independence. These are in turn connected to 16 water distribution systems which help in circulating water to households that are connected to Metro Water’s water grid. For example, raw water gets treated at Chembarambakkam treatment plant and is sent to two distribution systems at Porur and Mogappair for further distribution. Similarly, treated water from Red Hills goes to a distribution unit in the city and one lane transports raw water to Kilpauk plant to supply to core areas. In both scenarios, water travels through age-old pipes for a distance of 15 km-17 km. This is where the maximum amount of water is wasted. Areas that are located last in the distribution route like Saidapet, Washermanpet, Pulianthope, Purasawalkam and T Nagar to name a few, receive water at low pressure or sometimes get no water at all. “The water distribution system at Choolaimedu supplies water till Vadapalani and the one at Kilpauk sends water till T Nagar. In every zone, there are 400-odd streets that fall under this category of tail-end areas or defective pockets which hardly get any water due to low pressure. This is one of the greatest minuses of a centralised system,” said a former Metro Water official. Other than this, officials said if a sudden technical glitch comes up or the need to carry out repairs arises in any one of the water treatment plants, half of the city’s water supply will be cut off. Because present water treatment plants are of large capacities, upgrading them with latest technology is near impossible. Breaking the system Keeping in mind the many drawbacks of a centralised system, Metro Water will soon install mini modular water treatment plants at a few lakes identified as alternate sources. This way, the main source will not be changed, but each treatment plant will supply water to residents living in a five-km radius, minimising water loss via transmission. Within six to nine months, 10 MLD water treatment plants will be built at Retteri, Perumbakkam and Ayanambakkam lakes. Additionally, the capacity of the present 4-MLD water treatment plant at Porur will be increased to 10 MLD. Waterbodies in west Chennai like Ambattur, Korattur and Villivakkam lakes are also being considered by Metro Water to be brought under this new system. For example, an area like Karambakkam near Porur which suffers from the erratic supply will be supplied with water from the Veeranam dam instead of water from the Chembarambakkam dam. Each 10-MLD water treatment plant will have a command area of 5 sq km radius to which it will supply water from the nearest source. “After this drought comes to an end and once we establish regular supply, a decentralised system will be slowly introduced. Mini treatment plants are easy to maintain, cheaper to construct and water supply can be metered and monitored at the plant,” said a senior Metro Water official. Also, two 10 MLD tertiary treatment plants to recycle sewage will be built in Porur and Perungudi lakes on a pilot basis. This way the water cycle loop can be closed in a sustainable manner added the official.

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