Signs to look for
- Your water bill jumps, if you’re on a meter.
- Damp patches or stains on ceilings, walls or floors.
- Peeling paint, bubbling plaster or loose tiles.
- A musty smell, or mould that keeps coming back.
- Lower water pressure than usual.
- The sound of running water when nothing is on.
- Warm patches on the floor, which can mean a leaking hot water pipe underneath.
- Wet patches in the garden in dry weather.
Check your water meter
If you have a water meter, this simple test shows whether water is escaping. If you have a water tank in the loft, give it time to fill first.
- Turn off every tap, and anything that uses water, like the washing machine and dishwasher. Don’t flush the toilet.
- Write down the reading on your water meter.
- Wait 30 minutes without using any water, then read it again.
If the reading has gone up, water is escaping somewhere. Thames Water’s version of the test turns your stopcock off first: if the meter still moves, the leak is on the pipe between the meter and your stopcock.
What to do next
- If water is coming through a ceiling, turn off your stopcock.
- If water is near sockets or lights, switch the electricity off at the fuse box, if it’s safe to do so.
- Take photos of any damage for your insurer.
- Book a leak detection visit. We always use non-invasive methods first, and only dismantle if needed. Need a written report for your insurer? Tell us before the job starts.
Source: Thames Water, identifying leaks (checked October 2026).