India, Aug. 8 -- India's oldest metro corridor in Kolkata has decided to shift from traditional water-cooled chillers to air-cooled chillers, a move that would help it annually save around 180 million litres of water, enough to fill over 70 Olympic-sized swimming pools.

"In a bid to preserve groundwater, we are going to introduce a new type of cooling system in Kolkata Metro Railway's Blue Line, the oldest metro corridor in India. We are shifting from the traditional water-cooled chillers to air-cooled chillers," said a senior official of the Metro Railway in Kolkata.

The Blue Line of the Metro Railways is a 3.4 km stretch between Esplanade and Bhowanipore (Now Netaji Bhavan station) and was commissioned on October 24, 1984. It now runs...