Common warning signs
Unexpected meter movement, persistent damp, mould, paint failure, warm patches, reduced pressure and repeated water bills can all justify investigation. None proves where the leak is located, so avoid destructive opening until the available evidence has been narrowed down.
A sensible diagnostic sequence
Confirm whether the meter moves when known outlets are closed, isolate sections where possible, inspect exposed fittings and valves, then use appropriate non-destructive or minimally invasive methods based on the pipe type and building construction. The objective is to reduce the search area before opening walls, floors or ceilings.
Repair versus investigation
The person locating a leak and the person repairing the resulting pipework may use different tools and skills. A useful quote should make clear whether it covers investigation only, repair only, reinstatement of finishes, or all three.
When a leak appears to persist after repair
If water damage continues after an earlier repair, do not assume the first repair failed. A separate leak may remain elsewhere in the system. Repeat isolation and leak-detection testing should be used to establish whether the same point is leaking or whether there is another source.
Related information
Suspected Leaking Pipe in a Wall
Dampness does not by itself prove a concealed supply-pipe leak; drainage, waterproofing and external water can produce similar symptoms.
A Water Leak: What to Do in the First 30 Minutes
The first half hour is about safety, isolation, protecting contents and documenting the event.
Damp Wall Near Plumbing
Dampness near pipe routes can result from a concealed leak, waste leak, waterproofing failure, condensation or moisture from another source.
How to Use a Water Meter as a Leak Clue
A meter can show unexplained water use, but the result must be interpreted carefully before it is treated as proof of a concealed leak.