Not all water leaks are obvious. A burst pipe under a sink is hard to miss, but many leaks run silently behind walls, under floors, or underground in the garden for weeks before anyone notices. The longer a hidden leak runs, the more water it wastes and the more damage it causes. Here are the five most common signs you may have a water leak.
1. An unexpected increase in your water bill
A sudden jump in your water bill is one of the clearest signs of a hidden leak. Because hidden leaks run continuously, they waste water around the clock, which adds up significantly over a billing cycle. If your bill has risen without an obvious change in household usage, a leak is one of the first things to check. See our guide on sudden water bill increases
2. Damp patches or mould
Damp patches on walls, ceilings, or floors — especially where there's no obvious source — are a strong sign of a hidden leak. Mould growth is a particular warning, because mould needs constant moisture to thrive. If you're seeing mould in places that shouldn't be damp, a hidden leak may be feeding it. Musty smells in a particular room can also indicate a slow leak behind a wall.
3. The sound of running water when nothing is in use
If you can hear water running or trickling when no taps or appliances are on, water is moving somewhere it shouldn't be. This is often a leak in a pipe behind a wall or under the floor. Try turning off all taps and water-using appliances and listening carefully near walls and floors where plumbing runs.
4. Water meter activity when everything is off
This is the most definitive test. Turn off all taps and water-using appliances in the house, then check your water meter. If the meter is still moving, water is flowing somewhere — which means you have a leak. If you can isolate the hot water system, irrigation, and individual fixtures (by turning off their isolation valves), you can narrow down the source.
5. Damaged walls, floors, or ceilings
Long-running hidden leaks eventually cause visible damage: bubbling or peeling paint, warped or lifting floorboards, sagging plaster, or water stains on ceilings. By the time these signs appear, the leak has been running for some time, so it's worth investigating promptly to limit further damage.
Other signs to watch for
- Unexplained lush or green patches in the garden (a sign of an underground leak)
- Cracks in the driveway or paths near underground pipes
- A drop in water pressure (a leak reduces pressure to the fixtures downstream of it)
- Hot water running out faster than usual (a leak on the hot water line drains the tank)
What to do if you suspect a leak
If you've confirmed the water meter is moving with everything off, you have a leak. The next step is locating it. For leaks you can see — under a sink, at a fixture — you can often isolate and repair directly. For hidden leaks behind walls, under floors, or underground, professional leak detection using acoustic equipment can pinpoint the leak without destructive guesswork.
Our burst pipe and leak detection services use non-destructive acoustic leak detection to locate hidden leaks accurately. If you suspect a leak on the Gold Coast, contact our team to arrange detection before the leak causes further damage.
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