The tell-tale signs
Hidden leaks usually show themselves slowly. The longer they go unnoticed, the more damage they do to floors, plaster and joists – so it pays to know what to look for.
- Damp patches or staining on ceilings and walls, especially below bathrooms
- Flooring that lifts, bubbles, feels soft or smells musty
- Mould or a damp smell in a room that wasn't damp before
- The sound of running water when everything is turned off
- A water bill that's risen with no change in how you use water
- Low water pressure throughout the house
- A boiler that keeps losing pressure (on a sealed heating system)
A simple check with your water meter
If you have a water meter, turn off every tap and appliance that uses water, make sure the toilets have finished filling, and read the meter. Wait an hour or so without using any water and read it again. If the number has gone up, water is escaping somewhere – inside the house or on the supply pipe outside.
If you don't have a meter, listen at the stopcock with everything off. A faint hissing or running sound can point to a leak.
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Leaks that aren't plumbing
Not every damp patch is a plumbing leak. Rain getting in through a roof, a blocked gutter or a cracked downpipe can look very similar, as can condensation in a cold room. If the damp gets worse after heavy rain, the cause may be outside. If it's there in dry weather, or directly below a bathroom or kitchen, plumbing is more likely.
Finding and fixing the leak
A plumber will start by checking visible pipework and fittings near the damp area, then test sections of the system. Failed shower tray seals, leaking wastes and weeping compression joints are frequent culprits. If the leak is under a solid floor or inside a wall, specialist leak detection – thermal imaging, acoustic listening or tracer gas – may be needed to pinpoint it before anything is opened up.
Check your home insurance before work starts: many policies include trace and access cover, which pays for finding the leak and making good afterwards.
