The final option
With the surface and groundwater options either running dry or proving highly undependable, Chennai is now looking at the sea. In several parts of the world, desalination projects have reliably met the water needs of large urban populations and in a cost-effective manner. Chennai's experience with treating brackish groundwater has been positive (see table: Saline features). Metro Water has established five such units. Using the technology of reverse osmosis, the plants provide potable water to about 40,000 people at the rate of Rs 36 per kilolitre.
Exactly what will be the cost of a working desalination plant (treating seawater) in Chennai is not known as yet. A Rs 1,000 crore seawater desalination plant for Chennai is on the anvil. Union finance minister P Chidambaram, who is from Tamil Nadu, said the plant will be executed and operated by the state government. The Chennai Desal Company Limited was formed in June this year to take up desalination projects. The company's directors would include the managing director of Chennai Metro Water and the commissioner of the Chennai Corporation.
Varying estimates have been given for various technologies based on model desalination plants, with the minimum treatment cost of Rs 50 per kilolitre. The cost of desalinated water will far exceed the cost of water from other sources.
Saline features
Treating brackish water | | No of desalination plants | 5 | | Plants in operation | 4* | | Aggregate capital cost | Rs 1.73 crore | | Quantum of water produced | 500,000 litres per day | | Cost of water | Rs 36 per 1,000 litres | | Number of new borewells sunk | 5,500 | | Daily expenditure (in Rs lakh) | 55 | *The fifth plant is closed for maintenance
Source: Chennai Metro Water | |
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