Hidden leaks are expensive twice: once on the water bill and again in the damage they do quietly to slabs, walls and foundations. Most are found late because the early signs are easy to explain away.
The good news is that confirming whether you have a leak costs nothing and takes ten minutes with your water meter. Here is how, plus what the professionals do when the meter says yes.
The ten-minute meter test
Every Australian home with mains water has a meter, usually at the front boundary. It is the definitive leak detector and it is free.
- Turn off every tap and water-using appliance, inside and out; do not forget the toilet cisterns, irrigation and evaporative cooler
- Read the meter, including the small red or dial digits that measure litres
- Wait 30 to 60 minutes without using any water
- Read it again: any movement at all means water is flowing somewhere it should not be
- To isolate further, shut the house stop tap and repeat: if the meter still moves, the leak is in the pipe between meter and house; if it stops, the leak is inside
Warning signs people explain away
Individually these look like small maintenance quirks. Two or more together justify the meter test today:
- A water bill noticeably higher than the same quarter last year with no change in household
- Warm patches on a concrete slab floor (a hot water pipe leaking under the slab)
- The sound of running or hissing water when everything is off
- Damp patches, lifting paint, bubbling plaster or skirting that stays swollen
- Mould that returns in the same spot no matter how often it is cleaned
- One patch of lawn or garden that stays green and soft through a dry spell
- Low or fluctuating water pressure at one end of the house
The usual suspects
Toilets are the most common hidden leak in Australian homes: a worn outlet valve lets water trickle from cistern to bowl continuously, silently wasting hundreds of litres a day. Test by putting a few drops of food colouring in the cistern; if colour appears in the bowl within 15 minutes without flushing, the valve is leaking.
The other regulars are irrigation systems (buried, unmonitored, running at dawn), hot water system pressure relief valves that stick open, and the underground pipe from meter to house, especially where old galvanised pipe runs under a driveway.
What professional leak detection involves
A leak detection specialist arrives with acoustic listening equipment, thermal imaging cameras and, for stubborn cases, tracer gas that escapes through the pipe fault and is picked up at the surface. The point of all this gear is to locate the leak precisely so that only one hole gets dug or one tile lifted.
Expect to pay $300 to $600 for a standard detection visit, with the repair quoted separately once the leak is located. That fee routinely saves multiples of itself in avoided exploratory demolition. Many water utilities also offer a hidden leak allowance that partially rebates a leak-inflated bill once you provide evidence of professional repair, so keep the invoice.
Frequently asked questions
Will my water bill be reduced if a hidden leak caused it?+
Many Australian water utilities offer a one-off concealed leak allowance covering part of the excess water charge, provided the leak was concealed, repaired promptly by a licensed plumber and you supply the invoice. Check your utility's policy; claims usually must be lodged within a few months of repair.
Can a leak under a concrete slab be fixed without jackhammering?+
Often, yes. Once the leak is precisely located, options include cutting a small access point, rerouting that pipe section through the roof or wall cavity, or in some cases internal pipe coating. Rerouting is frequently cheaper and less disruptive than breaking the slab, which is why accurate detection matters so much.
How much water does a leaking toilet actually waste?+
A visibly running toilet can waste hundreds of litres per day, and even a silent cistern-to-bowl trickle adds up to tens of thousands of litres a year. It is consistently among the first things a plumber checks when a household queries a high bill.