Hidden leaks rarely announce themselves. By the time water is dripping through a ceiling, the leak has usually been running for weeks. Here are seven earlier warning signs worth taking seriously.
1. Your boiler keeps losing pressure
If you're topping up the pressure more than once a month, there's a leak somewhere in the heating circuit — almost always under floors or behind plasterboard.
2. Your water bill has quietly gone up
A sudden 20–30% increase in usage with no lifestyle change points to a mains or internal supply leak. Most water companies will waive part of the bill if you prove it with a detection report.
3. Damp patches that don't dry out
Persistent damp on one wall, especially near a bathroom or kitchen, is rarely condensation. It's usually a slow pipe leak wicking through the wall build-up.
4. Discoloured ceiling bulges
A brown stain on the ceiling is the leak telling you where it exits — not where it is. The actual source can be several metres away.
5. The sound of running water when nothing is on
If you can hear water moving behind walls late at night with all taps closed, you have an active leak somewhere in the supply or heating pipework.
6. A soft patch on the lawn, driveway or paving
This is the classic sign of an underground mains leak between the street and your property.
7. Mould, musty smells or warped flooring
Long-term low-volume leaks show up as mould in corners, musty smells in cupboards, or warping of laminate/engineered wood floors. None of these fix themselves.