Active Leak Detection

Detecting and pinpointing water network leaks through active leak detection can often be viewed as the easy task of water loss management projects. However, often it can be a key stumbling block if not correctly implemented. Successful water main leak detection programs have a few critical items in common:

  • Alignment with utility goals – ensuring the team you engage is working towards solving your problems and contributing towards all strategic goals of your utility (for example, our teams undergo customer service training given they have regular contact with domestic and commercial water customers).
  • Industry-leading equipment – a robust ‘leakage toolbox’ that includes listening sticks, ground microphones, leak noise correlators and acoustic leak detection devices (such as smart water IoT devices).
  • Innovative processes and methodologies – ensuring procedures leverage the power of new acoustic leak detection technologies while ensuring we operationalise field data promptly to reduce leak run-times and minimise leak impact on customer perceptions.
  • Value-add services and data management – recognising the opportunity to collect other valuable data from throughout the water network (examples include intelligence on broken assets, missing fittings and customer theft).
  • Engagement as a true partner – longer-term arrangements where we are an extension of your existing teams for active leak detection and water loss management.

Why conduct Active Leak Detection?

The purpose of active leak detection is to find all the leaks that do not surface or come to the attention of the water utility through their normal procedures (for example, customer contact centre, poor supply, or loss of water).  The process of active leak detection involves teams of skilled leak detection technicians actively surveying an area to find leaks generally using acoustic sounding techniques or similar. This may be in response to an increase in the minimum night flow (MNF) if the area is sectorised into a DMA or Virtual DMA, an increase in the output from a treatment works or suppler reservoir, or simply as a result of a systematic regular leak detection program at predetermined intervals.

How are leaks detected in water networks?

The majority of technologies for water main leak detection utilise acoustic principals to identify and pinpoint leak locations. A pressurised water pipe will create a unique acoustic signature at the leak location due to the pressure differential between the inside and outside of the pipe. The water main acts as a medium for transmitting the acoustic signature of the water leak.

When water is escaping the pipe and it is under pressure, it makes a distinct  ‘hissing’ sound that can carry significant distances along the length of the water pipe and be detected on nearby service connections, hydrants or stop valves. The distance which the leak can travel is influenced by several factors, but largely pipeline material and diameter. (For example, a 100 mm cast iron water main, will propagate the acoustic signal much better than a 300 mm PVC water main). Key factors that influence leak detection capability and accuracy:

  • Pipeline material
  • Pipeline diameter
  • Pipeline pressure
  • Leak size
  • Leak type (or more specifically, leak shape)
  • Backfill type
  • Access to appurtenances
  • Ambient and environmental noise

What technologies are required for Active Leak Detection?

Aqua Analytics uses a range of technologies when undertaking active leak detection work. Acoustic technologies are primary means of detecting and locating water main leaks. This method of acoustic leak detection is a systematic method of using acoustic equipment to survey the water network, identify leak sounds, and pinpoint the exact locations of any underground leaks. It is carried out in a systematic manner, walking all streets and listening on all available fittings (For example, acoustic leak detection surveys are similar to a postman who needs to go down all streets in a particular suburb to deliver the mail).

The most important technology of a leak detection technician is an amplified microphone that can be used to determine the presence of a nearby leak on a connection or appurtenance on the water network.

To pinpoint a leak, more advanced technologies will be used such as a leak noise correlator or ground microphone. At Aqua Analytics, we also use leak noise loggers (such as the Gutermann ZoneScan NB-IoT) from time-to-time when permanent leak detection is required in high consequence locations or when challenging leaks need to be located. A leak detection toolbox should contain the following technologies:

  • Amplified acoustic listening stick
  • Manual listening stick
  • Ground microphone
  • Leak noise correlator
  • Pipe and cable locator
  • Correlating leak noise loggers

If you already have a water loss management program underway, we can provide specialist active leak detection services. Aqua Analytics also provides ‘Leakage-as-a-Service’. These programs see us deploy acoustic leak detection IoT devices under a fully managed agreement to ensure uptime reliability and immediate leakage insights. This approach is particularly important for high consequence locations, such as CBD environments.

How do we find leaks on large diameter trunk mains?

Trunk mains, typically assets that are over 350 mm in diameter, require a different approach to reticulation assets when it comes to active leak detection. These are often assets that are critical to operations and it is important the current condition and presence of leaks is well understood to reduce the likelihood of failure.

Trunk main leak detection is challenging due to the reduced sound propagation in larger diameter pipelines. Many utilities avoid trunk main leak detection activities due to a perceived lack of leakage on these assets, however there are many examples from Australia and New Zealand that proves this is inaccurate. Trunk main leak detection can be delivered with the following solutions:

  1. Free-swimming leak detection technologies – a cylindrical device is inserted into a live pipeline, propelled by the water flow, and is captured downstream. Data is downloaded and the leak location is determined.
  2. Tethered leak detection technologies – a device is inserted into a live pipeline, attached to a long cable and propelled by the water flow. An operator will listen for the acoustic signal from the device hydrophone and determine if any leaks are present.
  3. Trunk main correlators – specialised hydrophones are placed on the trunk main (typically at 1-2 km spacings), listening for specific frequencies and applying traditional correlation equations to detect the presence of leaks.
  4. Real-time trunk main monitoring – specialised devices that monitor large diameter pipelines in real-time for changes in operating conditions that may indicate a new, development or growing leak.

How can Aqua Analytics help with our leak detection efforts?

Our team consists of internationally renowned experts on water leakage reduction, non-revenue water (NRW) and acoustic leak detection methodologies. Over several decades, we have developed customised water loss reduction strategies for conditions in Australia and New Zealand to ensure we achieve lower levels of water loss. We are viewed as leaders in active leak detection through our long-term engagements on projects in Sydney, Melbourne, Adelaide, Brisbane and throughout New Zealand.

If you are looking to achieve results from your active leak detection project – please contact us today.