Precious water can be lost through leaks and cracks in aged pipes over time and it is extremely difficult to locate such “hidden” leaks until water reaches the ground surface or shoot up high due to pressure in pipes. By turning to smart tools and new technologies such as leak monitoring sensors, inline pipe inspection tools and smartphone sensors, National Water Agency PUB seeks to enhance its leak detection capabilities to reduce water loss.
With a network of 5,700km water pipelines that conveys clean potable water to 1.6 million customers island wide, PUB has in place a comprehensive pipe maintenance and renewal programme, to ensure our water pipes and fittings are always in good working condition. Through regular inspection and replacement of old and leak-prone pipes, PUB now records 5 leaks per 100km of pipes per year, down from 10 leaks per 100km of pipes in 2014, and amongst the lowest incidence in the world.
As most pipes are underground, small leaks often go unnoticed and eventually develop into bigger leaks. With the use of acoustic sensors and innovative technologies, PUB has been able to locate and repair developing leaks before a pipe burst occurs. This will reduce water service disruption to customers as a badly leaking pipe would need to be shut-off for repairs to be carried out.
Smart tools for more accurate & effective leak detection
Leak monitoring sensors were first trialled in 2017, with 120 sensors installed along approximately 70km of large water mains for early detection of developing leaks. These sensors work by monitoring and analysing noise characteristics in pipes, for presence of leaks. The data is collated in a centralised server, and advanced analytics are used to monitor readings and alert PUB automatically when a leak is identified. The sensors are able to accurately identify and pinpoint the location of the leak within 3 metres along the pipe.
The trial was successful, with the sensors detecting 13 leaks over a three-year period. In one incident, the sensors alerted PUB to a potential leak on a 700mm diameter water pipe alongside a major expressway in 2018. Upon excavation, a 13mm corrosion hole was discovered at the bottom of the pipe, within 0.5 metres of the location reported by the sensors. This early detection allowed PUB to promptly repair the pipe and prevented further water loss. Following up from the trial, PUB plans to progressively scale up the number of sensors in the network and deploy 1,200 sensors islandwide for leak monitoring by 2021.
PUB is also exploring use of inline pipe inspection tools for leak detection in large water mains. The tool is inserted directly into the pipe, which allows for more targeted and precise inspection of the pipe wall, to detect any cracks or anomalies. Propelled by the flow of water in the pipe, these tools can easily survey long stretches of a pipe in a single deployment. One such tool is a ball-shaped sensor that can pinpoint the leak location to an accuracy of 2 metres by picking up acoustic or noise signature related to leaks. PUB will be deploying these sensors to survey 500km of pipes over the next five years.
For smaller water pipes, the PUB leak detection teams were recently equipped with smartphone sensors, a portable and easy-to-use survey tool that has proven to be effective in locating leaks. The sensor, connected to a smartphone, is placed on pipe fittings such as hydrants and valves1 to pick up sounds from the pipe. The smartphone automatically digitalises and analyses the acoustic signal in real-time via a dedicated mobile application to check for leaks. Two sensors can be deployed on separate pipe fittings at once to correlate and pinpoint the leak location within 2 metres along the pipe.
Mr Ridzuan Ismail, PUB’s Director of Water Supply (Network) 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 becoming a smart utility of the future.”
Evolution of leak detection methods over the years
In the early days of leak detection, operators and engineers listened for noise generated by water escaping from buried pipes under pressure. In the 1970’s, mechanical tools such as listening sticks were used to listen for pipe leaks but had limited accuracy as it relied on the hearing and experience of the engineer. There could also be interference from ambient noises in the environment, such as passing vehicles. Nonetheless, listening sticks are highly portable and particularly useful to confirm the precise location of the leak on site prior to excavation of the pipe.
In the early 2000’s, PUB started deploying noise loggers and correlators for more dynamic leak detection. Deployed during the night, the noise loggers would be used to inspect large areas of the pipe network and localise the leak to within a 100m stretch of pipe. Thereafter, the correlators were used to pinpoint the actual leak location on the pipe. Both methods are still in use today to complement the suite of tools for effective leak monitoring and detection.
Public feedback is also an important channel that PUB taps on for leak detection. PUB’s call centre operates 24 hours a day, and members of the public can contact PUB immediately to report any pipe leaks.