Chennai: Battling shortage, metro rail mulls ways to cut dependence on water

CHENNAI: Metro rail has made commuting across the city comfortable and easier, but it takes a large amount of resources like water to keep the facility running.


More than two lakh litres of water is used to run 32 metro stations every day. Nearly 64% of that goes to power the air conditioning systems in the 19 underground stations while the rest is used for the functioning of the 13 elevated stations and for other purposes.

Underground stations consume the most -- 9000 litres a station every day -- as air conditioning systems are kept running both at the concourse and platform level during the operational hours from 4.30am to 11pm.

“The AC systems require 7,000 litres a day for one station as water is used as a primary cooling medium and refrigerants as the secondary medium,” a metro rail official said.

Nearly 3,000 litres of water is used for the functioning of one elevated station. It is mostly used to power the AC systems inside the station control rooms and other rooms that house power systems.

“The water required for daily operations is supplied by Metrowater ,” a metro rail official said.

But Metrowater is struggling to meet the city’s water demands after an already delayed northeast monsoon failed to fill the reservoirs that feed the city. According to India Meteorological Department, rain deficit in Chennai was nearly 55% in the October-December monsoon last year.

To reduce its dependency on Metrowater and to cut down on the massive water consumption on a daily basis to run the network, metro rail has come up with several measures. It has started constructing a sewage treatment plant at Guindy metro station with a capacity of 10KLD. Officials said it is likely to be commissioned in a month.

“We will use this recycled water in restrooms, cleaning the stations and for gardening. We will also be building similar plants in other stations,” an official said.

At present, around 600 litres collected from AC condensation and RO rejects are being reused in restrooms and air-conditioning systems. But the biggest effort would come from metro rail adopting a new gas-based air conditioning technology for three underground stations under construction for phase-1 extension line to link north Chennai.

The new ‘variable refrigerant flow’ (VRF) technology will use refrigerants as the cooling medium. To be installed in three stations -- Washermenpet, Tondiarpet and Korukkupet -- the new technology, according to metro rail, is energy-efficient, requires less space and is cheaper than the existing system. Metro rail is also planning to adopt the same system in its 118.9km phase-2 project.