Tracer Gas Leak Detection in London and Surrey
For leaks in buried, screeded or boxed-in pipework where moisture meters and thermal cameras run out of answers, tracer gas finds the exit point without guesswork.
Tracer gas leak detection introduces a safe, non-toxic mix of hydrogen and nitrogen into an isolated, drained section of pipework. The gas escapes at the leak, rises through screed, soil, tiling or plaster, and is picked up at the surface by a sensitive detector. It is one of several methods DML uses, where appropriate, as part of a leak investigation; it is not the first tool out of the bag, because most leaks are found faster by moisture mapping and thermal imaging.
When tracer gas is the right method
- Central heating pipework under screed or suspended floors where pressure is dropping
- Underground mains supply pipes between the stopcock and the house
- Pipes inside concrete, behind tiling or in boxed-in ducts where opening up is costly
- Confirming the exact position after acoustic or thermal methods have narrowed the area
- Very small weeps that do not show as wet patches but keep tripping a pressure test
How a tracer gas test is carried out
- The suspect circuit is isolated and drained.
- Tracer gas is introduced at low pressure.
- The engineer sweeps the surface with the detector, marking the point of highest concentration.
- The result is cross-checked against the layout and other readings before the position is confirmed.
- The report records the location, the access route that will cause least damage, and the repair scope.
Non-invasive first, then precise
Our aim is to open one hole, in the right place, or none at all. The report tells you and your contractor exactly where to go. Repairs and reinstatement are quoted separately by our team or any contractor you choose, and the investigation report supports trace and access claims on your buildings insurance where the policy covers it.
We investigate across Greater London and Surrey. See areas we cover.
Frequently Asked Questions
Is tracer gas safe in my home?
Yes. The hydrogen content is well below flammable concentration and the mix is used routinely in domestic leak detection. The pipework is drained and isolated first.
Will you always use tracer gas?
No. We use it where appropriate. Many leaks are located with moisture profiling, thermal imaging or acoustic listening, which are quicker and cheaper for the client.
Can it find a leak under a tiled floor without lifting tiles?
In most cases, yes. Gas escapes through grout lines and small gaps, allowing the leak to be located to within a tile or two.
Does it work on mains pipes outside?
Yes, for buried supply pipes in gardens and driveways, often combined with acoustic correlation on longer runs.
Do you repair the pipe once found?
DML locates and reports. The repair is quoted separately by our team or your own plumber, using the exact location in our report.
Related services
- Leak detection
- Acoustic leak detection
- Thermal imaging surveys
- Central heating leaks
- Trace and access
Related reading: How thermal imaging leak detection works · Trace and access insurance cover explained
Pinpoint the leak
Independent leak detection using the right method for your property, across London and Surrey.
Last reviewed: 23 October 2026. Independent investigation and written reports. Repairs are quoted separately.