'Chennai's desalinated water will be expensive'

Chennai, the capital of Tamil Nadu, has always been known for its chronic water problems.

Chennai's Metropolitan Water Supply and Sewage Board, or Metrowater as it is better known, which is in charge of the city's water supply, recently announced that a desalination plant had been set up that would supply 100 million litres per day (MLD) of drinking water to the parched city. A plant that would supply water once in three days, even if all the reservoirs ran dry.

A Ganesh Nadar spoke to Sunil Paliwal, managing director of Metrowater, about the existing supply and future plans to augment Chennai's water supply.

Tell us about this new desalination plant.

It is in Minjur, Chennai, and is being implemented under a DEBOOT plan, ie, design, build, own, operate, transfer. The transfer will be after 25 years. We gave the land. A special project vehicle was created, IVRCL, with Befessa of Spain, for the purpose.

That is the company which will implement this project. We also have an agreement to buy that water from them at Rs.48.66 per kilo litre, which is less than 5 paise per litre. This rate is for one year only. After that the rate is flexible and will depend on the rate of power supplied to them.

To supply 100 MLD of water they will be using 237 MLD of seawater. After desalination the remaining 137 MLD will be pumped back into the sea.

Won't that affect marine life?

It will not. The process results in the temperature of water going up by 5 degrees. It is ok up to 7 degrees by international standards. Here the difference will not exceed 5 degrees. As for salinity, the area affected is only 50 metres by 100 metres. Beyond that it completely dissipates in the seawater. Thus sea life will not be affected.

What about erosion of the sea wall near the plant where they are drawing in water?

Water pipes have been put up keeping the wind direction in mind. The water will not be pumped in. It will flow in because of gravity. There will be a filter to make sure sea life does not come in with the water. We have told them to put additional concrete blocks on both sides of the pipe drawing in water.

The water being discharged goes in the opposite direction so that it doesn't come back immediately.

What is the cost of water to the government?

The present cost of water to us is Rs 7 per kilo litre when we get it from our reservoirs, Rs 12 per kilo litre when we get it from the Veeranam project. The desalination plant water is expensive in comparison, at almost Rs 49 a kilolitre.

At present we are supplying 655 MLD (million liters per day).

What is the capacity of the present water sources and how much will be added by this plant?

At present our reservoirs are Red hills, Poondi, Chembarapakkam and Sholavandan. The total capacity if all of them are full is 3,11,300 ML (million litres). This will add 100 ML per day which means 36,500 ML a year. The total capacity will be enhanced by almost 12 per cent.

Please keep in mind that we lose up to 50 per cent of the water in the reservoirs due to evaporation.

A city like Mumbai has four times the population of Chennai and still has a better water supply system. Why can't you do that?

The problem is not with the infrastructure but with the source. Mumbai has a much better water source because of the Western ghats. The availability of water is more there. Chennai is rain-dependent only. Mumbai gets its water from reservoirs in the Western ghats which are well-fed.

Will power cuts affect the supply of water from the desalination plant?

There will be no power cut for the plant. It has separate transformers which are linked to two substations. Even if the supply fails from one substation it will be supplied from the other station.

There is a complaint against Metrowater, that even those buildings that don't have water or drainage facilities have to pay charges?

That is the law. You are supposed to pay 30 pc tax of the rental value of the building, of which  23 pc goes to the municipal corporation and we get 7 pc.

Unlike a city like Mumbai where the expansion is vertical, Chennai can expand in three directions. The city is expanding at a very fast pace. Is Metrowater keeping pace? What are your plans for the newly developing areas?

Some 45 local bodies around the city have been identified for projects. Project reports for underground drainage system have been prepared. The same goes for water supply. We will soon be applying for funds and the schemes will be implemented as the population grows.

Recently it was announced that skyscrapers, hitherto unknown in Chennai, will now be allowed to come up. This will result in larger population in a limited area. What are your plans for these buildings?

At the moment the pipeline will not support additional water supply. We will put up bigger pipes as the needs grow.

What about sewerage treatment?

The sewage generated per day in the city is normally 430 MLD. We already have the capacity to treat 486 MLD. We have called for tenders for another 60MLD. We have applied for funds for another 54 MLD. There is another 12 MLD in the planning stage. 

What about charges to the consumers?

Domestic consumers pay us Rs 50 per month and there is no meter. This is very low. We need massive inputs of funds for infrastructure. Industrial consumers pay more and they are metered.