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SINGAPORE: When Ong Guan joined what was then the Public Service Board (PUB) as a technician in 1976, detecting water leaks was a tedious and time-consuming business.
“Sometimes my boss would tell me, can you go at 2 a.m. to track down (the leak)?” recalled the 66-year-old.
Leak detection was often done late into the night as it would be too noisy during the day to be able to detect the source of a leak, he explained.
And determining the exact source of a leak was a process of trial and error, involving a lot of walking, Ong said.
The tools at the time were quite rudimentary, and the main device for operators and engineers was a listening stick, a 1.5m long stainless steel rod placed in the ground to detect water leaks from buried pipes.
Singapore has a 5,700km-long network of water pipes, supplying clean, potable water throughout the island.
Regular inspection and replacement of old pipes means that the country experiences only five leaks per 100 km of pipes per year, up from 10 leaks per 100 km of pipes in 2014, among the lowest incidence rates in the world.
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It’s impossible for a network of water pipes to not leak, said Waseem Khan, a senior engineer in the PUB’s water supply networks department.
Aging water pipes, wear and tear, corrosion, changing soil conditions, corrosion and damage from excavation all could contribute to leaks, said Khan, who heads the unit for leak detection.
In most cases, such leaks do not affect the water supplied to households here, he said.
“In the event that it is necessary to close the supply to the customer, we will ensure that the customer receives continuous water by providing a temporary supply of water,” he said.
And while leaks where water shoots into the air like a geyser often attract public attention, there is no cause for concern, Khan said.
“Our pipes are pressurized pipes,” he said, explaining that pressurized water inside pipes tends to shoot out if there is a leak.
“It is very normal. If you see water shooting into the sky, it is not a cause for alarm. Back off, be safe, call the proper authorities and we can rectify the situation. “
A listening stick is one of the oldest tools the PUB has for detecting leaks, depending largely on the hearing and experience of the engineer. (Photo: PUB)
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TIMELESS TOOLS AND NEW TECHNOLOGY
Equipment such as listening sticks are “timeless tools” of the trade for detecting leaks, he said.
Still, the national water agency is expanding its arsenal of equipment to include smart tools and new technologies.
“PUB is always looking for new technologies for the early detection of leaks, so that we can minimize the loss of water in the network and increase the resilience of the service we provide to our customers,” said the director of the supply network of PUB water, Ridzuan Ismail.
These include noise loggers and correlators, first implemented in the early 2000s.
Noise loggers can survey large areas of Singapore’s pipeline network and locate leaks over a 100m span, and then correlators are used to identify the exact location of the leak in a pipeline.
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In 2017, PUB began testing the use of leak monitoring sensors, with 120 sensors installed along some 70 km of large water pipes.
These sensors, which work by monitoring and analyzing noises in pipes for the presence of leaks, are capable of locating the location of a leak within 3 m along a pipeline, with advanced analytics used to monitor the readings and automatically alert PUB in the event of a leak.
The sensors managed to detect 13 leaks over a three-year period and in 2018 alerted PUB to a possible leak in a water pipeline along a major highway, which turned out to be a 13mm corrosion hole at the bottom of The pipe.
PUB aims to have 1,200 of these sensors across the island by next year, Khan said.
The agency is also exploring the use of online pipe inspection tools, which are inserted directly into large water pipes, allowing for more accurate inspection of pipe walls for cracks or abnormalities.
These tools are carried by the flow of water in the pipes and can therefore inspect long stretches with a single deployment.
One such tool, a ball-shaped sensor, can pinpoint the location of leaks to two meters using acoustic and noise signatures, Khan said.
PUB aims to use such sensors to inspect around 500 km of pipeline over the next five years.
This ball-shaped inline pipe inspection tool is carried by the flow of water in the pipes and can therefore inspect long lengths at a time. (Photo: Zhaki Abdullah)
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The agency’s leak detection teams were also recently outfitted with smartphone sensors.
Sensors connected to a telephone are attached to pipe accessories, such as hydrants and valves, to pick up sounds from pipes.
An app on the phone analyzes the acoustic signal in real time to check for leaks. The use of two sensors, placed in two separate pipe fittings, can also identify leaks within two meters.
These tools have made the job of leak detection much easier, Khan said.
“When you are using the listening stick, it is actually very complicated because there are other ambient noises present: vehicle traffic, people are using water, the ambient noises that are present. And you have to do all that processing and filtering in your brain and that takes years and years of training, “he said.
“Whereas if you are using a smartphone sensor, as we are doing now, all that filtering amplification is happening on the phone. So all the user has to do is listen for the noise of the leak. “
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Mr Ong is now an engineer and oversees the routine and ad-hoc leak detection of the water supply network in East Singapore.
His years of experience have taken him to Brunei and Mauritius to provide leak detection consulting services to the two countries.
Meanwhile, his willingness to learn has helped him embrace the new technologies that PUB is employing, and Mr. Ong noted that such tools have made leak detection easier and more accurate.
“No more, no more,” he told reporters with a smile, when asked if he still had to walk at 2 a.m. to find leaks.
