Most leaks don't announce themselves with a burst pipe and water pouring through the ceiling. The costly ones hide — inside walls, under floors, beneath the house — quietly wasting water and damaging timber, plaster and concrete for months before the first stain appears. By then the repair bill is bigger than it needed to be. Here are the checks we suggest to catch a hidden leak early, and when it's time to call us in.
Signs there's a leak you can't see
Your house will usually tell you something's wrong before you ever see water:
- A water bill that's crept up. Compare the usage figures, not just the total. A steady rise with no change in the household points to water going somewhere it shouldn't.
- Musty smells or new mould. Damp behind walls and under floors feeds mould, especially in bathrooms, laundries and kitchens.
- Stains, bubbling paint or soft plasterboard on walls and ceilings, or skirting boards that are swollen or discoloured.
- Floors that warp, lift or feel spongy, particularly near wet areas.
- The sound of running water or hissing when every tap in the house is off.
- A warm patch on a slab floor. Often a hot water line leaking underneath.
- Water pressure that's dropped off across the whole house.
- A suspiciously green patch of lawn, or soggy ground that never dries out — a classic sign of an underground pipe leaking.
The water meter test
This is the quickest way to confirm a leak, and it costs nothing:
- Turn off every tap, the dishwasher, washing machine and any irrigation. Don't flush the toilet during the test.
- Find your water meter — usually near the front boundary — and write down the reading. Many meters also have a small leak indicator dial.
- Wait 30 to 60 minutes without using any water.
- Check the meter again. If the reading has moved, or the small dial is still turning, you've got a leak somewhere.
To check the toilet, put a few drops of food colouring in the cistern and wait 15 minutes. If colour shows up in the bowl without flushing, the outlet valve is leaking — one of the most common hidden water wasters we find.
Where hidden leaks usually turn up
In the homes we work on across the Northern Beaches and North Shore, the usual suspects are:
- Under sinks and behind dishwashers and washing machines
- Hot water systems, especially the relief valve line that drains away outside unnoticed
- Shower recesses with failed waterproofing
- Old galvanised or copper pipes under the house that have corroded through
- The underground supply line between the meter and the house
- Garden irrigation with a cracked join
Found a leak? What to do next
If water is actively escaping, turn the supply off at the meter straight away and treat it as an emergency — especially if it's anywhere near power points or appliances.
There's another reason not to sit on it: insurers generally cover sudden damage but can knock back claims for leaks that have clearly been running for months. Early detection protects your claim as well as your house.
For everything else, the sooner a leak is pinpointed the less it costs. We use acoustic listening gear, thermal imaging and moisture meters to find leaks without tearing walls or floors apart, then fix the pipe properly the first time. If any of the signs above sound familiar, get in touch through our general plumbing maintenance page or call us on 0450 876 713. A hidden leak never fixes itself, and it never gets cheaper on its own.
