About one million litres a day has been leaking out of the Chakka point, officials say, for eight years.

Do you know that half the drinking water piped to the State capital by the Kerala Water Authority (KWA) vanishes into thin air?

Official statistics show that out of the 300 million litres a day (MLD) of drinking water sent to the pipelines in the city, only 150 MLD is accounted for. What happens to the rest, official sources say, remains unknown.

“It can be distribution loss, leak or illegal connections. But the fact is that only 150 MLD is billed, and we do not know where the rest goes,” a senior official told The Hindu on Monday.

The utility has been troubled for years by leaks from underground pipelines, most of them of 1933 vintage, but has been unable to pinpoint from where exactly the water is gushing out. One such leak point is right in front of the utility’s headquarters at Vellayambalam, while another is at Chakka, near the airport.

About one million litres a day has been leaking out of the Chakka point, officials say, for eight years. But efforts to trace the exact point have been unsuccessful since digging up the entire area is impractical.

The situation, finally, has prompted the utility to look at a novel way for inline leak detection. The KWA Board, which met here on Monday, reportedly approved the deployment of two technologies on an experimental basis.

One is to use SmartBall, an acoustic leak-detection sensor developed by the Canada-based Pure Technologies Ltd. The foam ball, a free-swimming inline leak-detection system designed to operate in live water mains, has an instrument-filled aluminium alloy core capable of detecting and locating very small leaks and air pockets in pipelines. It is inserted into a pipeline to travel with the water and collect information.

The second technology is Sahara, also from Pure Technologies but costlier, which shoots videos as well of the pipe interiors and comprises a small drag chute which uses the flow of water to draw the sensor through the pipeline, recording visuals on the way.

The utility’s plan is to deploy both technologies on an experimental basis for about 35 km of pipes in Thiruvananthapuram, Kochi and Kozhikode, starting with the State capital. The initial idea is sign a contract with the firm and to see how they work before thinking about acquiring any of the two.

“These will help us find the leakages, quantify the loss and tell us the condition of our pipeline network, which is about 80 years old and has never been inspected at a micro level. We can detect illegal connections as well,” a KWA official said, adding that the cost factors and other modalities would be worked out shortly.