Chennai: One day in April, Shyamala Sitaraman, a resident of Chennai’s Valmiki Nagar, discovered that her underground tank was overflowing. Sumps are an essential part of life in the water-starved Tamil Nadu capital—the taps are left open to collect the thin trickle supplied by the Chennai Metropolitan Water Supply and Sewerage Board but the tanks never fill up.

The overflowing tank was therefore a matter of some astonishment. And it wasn’t just hers, every underground tank in the neighbourhood was overflowing, flooding the streets.

Sitaraman, 70, and several others called the water board. “We thought some pipe had been broken and water was just overflowing," she said.

Two days and several calls later, Sitaraman had her answer—she was receiving water from the Nemmeli desalination plant 25 km away.

“It is unbelievable—making potable water from sea water," says Sitaraman, whose home in southern Chennai is near the beach. She could “have never imagined it".

Chennai, with a coastline that stretches about 26 km along India’s east, may well be among the first Indian cities to depend on desalination for most of its water needs.

Last month, Tamil Nadu chief minister J. Jayalalithaa announced a plan to install another desalination plant next to the newly inaugurated Nemmeli facility to treat 150 million litres per day (mld) of sea water, costing 1,000 crore.

That will be in addition to a plant being set up in Pattipulam near Chennai with a capacity to treat 200 mld of sea water, expandable to 400 mld, expected to be completed in four years. The state’s first desalination facility began operating in Minjur in Thiruvallur district in 2010. Both this and the Nemmeli plant have a capacity of 100 mld each.

Add this up and Chennai could have a total supply of 550-750 mld of desalinated water in a few years. That’s 66-90% of the 831 mld of drinking water Chennai’s 4.6 million residents need today.

While the country is home to several low-capacity plants, this is the first time that any state has set up desalination units with a capacity of 100 mld. While Andhra Pradesh and Orissa are also debating the prospects of setting up such plants, Gujarat seems to be further along the way towards having its own desalination units.

But building that capacity won’t be easy.

The Nemmeli plant inaugurated in February was delayed for years by political bickering and execution hurdles. The plant was to be built at a cost of 1,000 crore to pump out 300 mld of treated sea water. While the cost remained at 1,000 crore, the capacity was whittled down to 100 mld.

It was the first large Centrally funded desalination facility to be announced in the country, by P. Chidambaram in July 2004. He was then Union finance minister as he is now, having been the home minister for a time in between.

After the announcement, the Union and the Tamil Nadu governments took about four years to reach a consensus on aspects such as the location and the agency that would build the plant, with Jayalalithaa and Chidambaram blaming the other for the delays. The state government then took two more years to seek bids for the project.

The winning consortium of Chennai-based water management company Va Tech Wabag and Israel-based IDE Technologies Ltd, which specialises in desalination, needed another three years to complete the plant. It has a contract to manage the plant for the next seven years.

The construction was interrupted by the Jal cyclone in November 2010 that washed away a pipeline into the sea, and the Thane cyclone in December 2011 that caused heavy destruction to the marine works, said Rajiv Mittal, managing director of Va Tech Wabag.

“Projects are announced by government in pomp and glory but it takes years before they are finally implemented," says 81-year-old A.K. Sitaraman, Shyamala’s husband.

Desalination isn’t seen as a natural fit for India, despite the country being a peninsula, mainly because of the costs involved. The technology—of separating brine from sea water to make it potable for daily use—is expensive and energy-intensive. That’s why it’s adopted mostly by countries in the Arabian Gulf such as Saudi Arabia that have the money and abundant energy supplies while lacking adequate sources of water—they account for over 50% of world capacity.

Apart from the cost, for every 100 mld of sea water treated, only 40 mld is made potable and the remaining 60 mld of concentrated saline water has to be discharged into the sea.

This discharge by desalination plants impacts marine ecology, says S.S Sivakumar, managing trustee of Pure Water Foundation, Thiruvanmiyur, an organization focused on increasing the availability of clean water to the poor through environmentally safe solutions.

Despite this, “increasing population, industrialization and demand for fresh water has been driving (the) India desalination market, which is all set to grow further at CAGR (compounded annual growth rate) of around 22% for next five years," TechSci Research, a global market research firm, said in a 2012 report.

Growth in India is faster than initially anticipated, TechSci said. It sees India acting as a growth engine for the global water desalination industry.

Corrado Sommariva, president of the US-based International Desalination Association lobby group, insists that the overall lifecycle cost and tariffs, ranging between $0.7 and $1.5 per cubic metre globally, are almost comparable with that of traditional water suppliers.

B. Chandramohan, managing director of the Chennai Metropolitan Water Supply and Sewerage Board, admitted water produced by the process was expensive, but declined to comment on the cost of producing one litre of desalinated water.

Among other coastal states in India, Gujarat is also investing heavily in desalination plants. In March, a consortium of Japanese and Singaporean companies signed a pact with the Gujarat government to build a 300 mld desalination plant in Dahej, involving an investment of about 3,000 crore.

Chennai suffers frequent droughts. The three main waterlines—the Cooum and Adyar rivers and the Buckingham Canal—that flow through the city en route to the Bay of Bengal are too polluted or scant for regular use or to replenish ground water. Most of the average annual rainwater of 1,200-1,300 mm that Chennai receives—more than Bangalore’s 900 mm or Delhi’s 800 mm average—flows into the sea.

The southern city may be headed for another year of scarce water supply because of poor rainfall last year. The combined water level of the three main reservoirs—Poondi, Chembarakkam and Red Hills—that supply water to Chennai was at 2,922 million cubic feet ( it is 2,889) on 8 May, down 47% (it is 48 %) from a year ago.

Desalination cannot be a solution in itself, says R.Sakthivadivel, emeritus professor at the Centre of Water Resources at Anna University, a premier technology institute in Tamil Nadu.

Leaks and pilferage are the bane of Chennai’s water distribution network, he says, adding that only 65% of the water from the city’s treatment plants reach consumers while in Germany this is as high as 95%. That gap needs to be plugged, especially if the people of the state are paying a heavy price for water that’s currently gushing through some of Chennai’s taps.

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