SINGAPORE: When Ong Guan joined what was then the Public Utilities Board (PUB) as a technician in 1976, detecting water leaks was a tedious, time-consuming affair.
“Sometimes my boss would tell me, can you go at 2am to trace (the leak)?” the 66-year-old recalled.
Detecting leaks 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 trial-and-error process, involving a lot of walking around, said Mr Ong.
The tools back then were quite rudimentary, with the main device for operators and engineers being a listening stick, a 1.5m long stainless steel rod placed on the ground to pick out water leaks from buried pipes.
Singapore has a 5,700km-long network of water pipelines, supplying clean and potable water islandwide.
Regular inspection and replacement of old pipes means the country experiences just five leaks per 100km of pipes per year - down from 10 leaks per 100km of pipes in 2014 - among the lowest incidence rates in the world.
It is impossible for a water pipe network to have no leaks, said Waseem Khan, a senior engineer with the PUB’s water supply network department.
Ageing water pipes, wear and tear, corrosion, changing soil conditions, corrosion and damage caused by excavation - all these could contribute to leaks occurring, said Mr Khan, who leads the leak detection unit.
In most cases such leaks do not affect the water supplied to households here, he said.
“In the event that there is a need for us to shut supply to the customer, we will ensure that the customer receives continuous water by giving them temporary water supply,” he said.
And while leaks where the water shoots up in the air like a geyser often attracts the attention of members of the public, there is no cause for concern, said Mr Khan.
“Our pipelines are pressurised pipelines,” he said, explaining that the pressurised water within the pipes tends to shoot out if there is a leak.
“It's very normal. If you see water shooting up into the sky, it's no cause to be alarmed. Stand back, be safe, call in to the relevant authorities and we'll be able to rectify the situation.”
TIMELESS TOOLS AND NEW TECHNOLOGY
Equipment such as listening sticks are “timeless tools” of the trade in detecting leaks, he said.
Even so, the national water agency is expanding its arsenal of equipment to include smart tools and new technologies.
“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,” said PUB water supply network director Ridzuan Ismail.
These include noise loggers and correlators, first deployed in the early 2000s.
Noise loggers can inspect large areas of Singapore’s pipe network and localise leaks to within a 100m stretch, with correlators subsequently used to pinpoint the exact location of the leak on a pipe.
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In 2017, PUB started testing the use of leak monitoring sensors, with 120 sensors installed along about 70km of large water mains.
These sensors, which work by monitoring and analysing noises in pipes for the presence of leaks, are able to pinpoint the location of a leak to within 3m along a pipe, with advanced analytics used to monitor 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 potential leak on a water pipe along a major expressway, which turned out to be a 13mm corrosion hole at the bottom of the pipe.
PUB aims to have 1,200 such sensors islandwide by next year, said Mr Khan.
The agency is also exploring the use of inline pipe inspection tools, which are inserted directly into large water mains, allowing for more precise inspection of pipe walls to detect cracks or anomalies.
These tools are carried along by the flow of water in pipes and are thus able to survey long stretches in a single deployment.
One such tool, a ball-shaped sensor, can pinpoint leak locations to within two metres using acoustic and noise signatures, Mr Khan noted.
PUB aims to use such sensors to survey around 500km of pipes over the next five years.
The agency’s leak detection teams were also recently equipped with smartphone sensors.
Sensors connected to a phone are placed on pipe fittings such as hydrants and valves to pick up sounds from pipes.
An application on the phone analyses the acoustic signal in real-time to check for leaks. The use of two sensors, placed on two separate pipe fittings can also pinpoint leaks to within two metres.
Such tools have made the job of leak detection much easier, said Mr Khan.
“When you're using the listening stick, it actually is very complicated because there are other ambient noises present - the vehicular traffic, people are using water, environmental 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're using a smartphone sensor, as we are right now, all that filtering amplification is going on in the phone. So all the user actually needs to do is listen out for the leak noise.”
Mr Ong is now an engineer, overseeing both routine and ad-hoc leak detection of the water supply network in the east of Singapore.
His years of experience have brought him to Brunei and Mauritius to provide leak detection consultancy services to the two countries.
Meanwhile, his willingness to learn has helped him pick up the new technologies the PUB is employing, with Mr Ong noting such tools have made detecting leaks easier and more accurate.
“No more, no more,” he told reporters with a laugh, when asked if he still had to walk around at 2am to find leaks.