1,200 leak monitoring sensors to be deployed islandwide

Some 1,200 leak monitoring sensors are to be deployed islandwide before the end of next year, adding to PUB's toolkit of new leak detection technologies.

The water agency said last Friday that 120 such sensors currently line the large water mains here, monitoring and analysing noises in the pipes to pick up the presence of leaks.

These sensors are able to accurately identify and pinpoint the location of a leak within 3m.

In the three years since the sensors were piloted in 2017, they have detected 13 leaks - including a 13mm hole at the base of a pipe beside a major expressway.

While some may think water leaks are a rare occurrence here, PUB has recorded about five leaks per 100km of pipes yearly in recent years. As Singapore's pipe network stretches over about 5,700km, this makes for about 285 leaks a year, or about five a week.

Mr Waseem Khan, 31, who leads PUB's leak detection unit, clarified that this is actually one of the lowest rates in the world. The senior engineer added that it is not possible to have no leaks in a water system.

"As your pipeline ages, it undergoes wear and tear. (Also), with the soil condition, you might have corrosion. You might have works ongoing, so third-party damage might occur when someone excavates and hits your pipe," he said.

PUB said it is important to continually detect and repair leaks - even small ones - before they escalate, in order to conserve precious water.

The agency last Friday unveiled several new technologies that assist in this endeavour.

These include SmartBall - a round sensor encased in a protective foam covering. It is put into a pipe and propelled along by the flow of the water.

The sensor detects any cracks or anomalies along the walls of the pipe by picking up noise signatures related to leaks. It can survey long stretches of pipe in a single deployment.

Over 500km of pipes will be monitored by these sensors over the next five years, said the agency.

PUB's leak detection teams have also been equipped with smartphone sensors since last year.

One end of the sensor is attached to any smartphone, while the other is placed on a pipe fitting to pick up sounds from the pipe.

An app on the phone will automatically digitise and analyse the sounds picked up by the sensor, while filtering out any ambient noise, accurately pinpointing the location of any leaks.

These complement the noise loggers and correlators, devices introduced in the 2000s that also help to check for leaks.

The use of technology has reduced training time for new technicians, said Mr Khan. "Previously, you'd need a few months, maybe even years, depending on the person, to be able to train them up to use some of these tools for leak detection. Now, with the implementation of technology, the learning curve has shortened to maybe a few weeks, a few months."

PUB director of water supply (network) Ridzuan Ismail said: "PUB is always on the lookout for new technologies for early leak detection, so that we can minimise water loss in the network and increase the resilience of service that we provide to our customers.

"With intelligent leak monitoring and detection technology, we are taking a more preventive and predictive approach and moving away from a resource-intensive operation that requires very specialised skills. This will bring us closer to our goal of transforming our operations through digitalisation to become a smart utility of the future."

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Big leap from 'stethoscope' of yore

When Mr Ong Guan started working as a PUB technician in 1976, he made for an odd sight - with a device that looked like a stethoscope in his ears, the other end connected to two metal discs on the ground.

That was par for the course at the time, as the equipment he was using - known as geophones - was necessary to pinpoint the position of leaks in underground water pipes.

Trained technicians would first press a metal stick with a disc on one end, called a listening stick, against pipe valves to listen for faint noises generated by water escaping from the pressurised pipes.

If they heard an abnormal noise, they would then put on the geophones and slowly walk along the length of ground above the pipes, trying to listen for where the sound was loudest.

But the equipment would also pick up noises such as that of passing cars and ambient sounds. So technicians would have to stand still and tune out the other sounds in their head, focusing only on the faint noise of underground water.

"Sometimes my boss would tell me: 'Can you go and (check the pipes) at 2am?' Because it would be too noisy before then," Mr Ong said last Friday.

Now an engineer at PUB, the 66-year-old recalled it being an extremely tedious and time-consuming process that relied on trial and error and took a lot of manpower.

But things have improved greatly since. Said Mr Ong: "Now, with the (technology), we're able to analyse more accurately... You just need to key in something and it'll tell you where the next (leak) spot is."