Not long ago, finding a hidden leak meant lifting floorboards and chasing walls until the water turned up. Today, specialist equipment can pinpoint most leaks to within a small area before anything is opened up. Here is how the main methods work. This is how leak detection works in practice.
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How leak detection works: pressure testing first
Before searching, the system is often pressure tested to confirm there is a leak and which part of the system it is on, for example the cold supply, hot water or heating circuit. This narrows down the search straight away.
Thermal imaging
A thermal camera shows temperature differences across walls, floors and ceilings. Hot water and heating leaks show up as warm patches, while evaporating water from cold leaks can show as cooler areas. It is fast and completely non-invasive, and it works especially well for underfloor heating pipes and leaks in screed.
Acoustic leak detection
Water escaping under pressure makes a distinctive noise. Sensitive ground microphones and listening sticks amplify that sound so an engineer can follow it along the pipe run and find where it is loudest. This works well for pressurised pipes under concrete floors, gardens and driveways.
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Tracer gas
For leaks that are hard to hear or see, the pipe is drained and filled with a safe tracer gas mix. The gas escapes through the leak and rises through floors, soil or paving, where a sensitive detector picks it up. It is very accurate for small leaks and long pipe runs, including the supply pipe from the street.
Moisture meters and endoscopes
Moisture meters map how far water has spread through plaster and timber. Small inspection cameras can look inside voids and behind panels through a tiny hole, avoiding larger openings.
After the leak is found
You get a clear location, and usually photos, which is useful for your insurer. The repair is then made by opening up only the small area needed, which keeps making-good costs down.
Frequently asked questions
Is tracer gas safe?
Yes. The gas used is a safe, non-toxic mix designed for leak detection.
Will you need to lift floors?
Only a small area at the exact leak point, once it has been located.
Does insurance cover leak detection?
Many home insurance policies include “trace and access” cover. Check your policy.
