The most expensive leaks are rarely the ones you can see. A dripping tap gets fixed within the week. A pipe weeping quietly under a slab or inside a wall can run for months, softening timber, feeding mould and adding a little to every water bill until someone finally asks why the numbers keep climbing.
The good news is that hidden leaks leave clues, and you can gather many of them yourself. This guide covers the warning signs, a simple meter test you can run at home, the places leaks like to hide, and how professionals find them without tearing your house apart. If you are searching for water leak detection in Perth, it is a good place to start.
Why Hidden Leaks Are Worth Chasing Early
Finding a hidden leak is a skilled job, and it helps to understand what is involved before you book anyone. A plumber’s work is largely about tracking down the hidden water leaks pushing up bills before they damage your home, and the earlier that happens, the smaller the repair tends to be.
Water does not stay put. It follows gravity and the path of least resistance, so the wet patch you notice is often some distance from the actual break. Left alone, a small leak can undermine paving, damage plasterboard and flooring, and encourage mould. That is why a mysterious rise in your bill is worth taking seriously, even when nothing looks wrong.
Warning Signs of a Hidden Leak
One sign on its own can have an innocent explanation. Several together deserve attention. Watch for:
- A water bill that has crept up without any change in how you use water.
- A meter that keeps moving when everything is switched off.
- Damp, stained or bubbling paint or plaster on walls and ceilings.
- A musty smell, or mould appearing in places it did not used to.
- Cracked, lifting or sunken paving, or a soft patch of ground.
- A section of lawn that is unusually lush or boggy compared with the rest.
- The faint sound of running water when the house is quiet.
- Reduced water pressure at taps.
The Water Meter Test You Can Do at Home

Your meter is the simplest leak detector you own. The Water Corporation explains that if the dial changes when no water is being used, you may have a leak. It is usually in the front garden close to the verge. The steps are simple:
- Turn off all taps and every appliance that uses water, and check that nothing automatic, such as a dishwasher or irrigation controller, is about to start.
- Record the numbers on the meter, including the red digits.
- Wait without using any water. Many guides suggest at least 15 minutes, and a longer wait shows a slow leak more clearly.
- Read the meter again. If the numbers have changed, water is going somewhere.
The Water Corporation’s own guide to detecting a leak includes a meter reading template and steps for smart meters, so check it for the method that suits your meter.
A moving meter does not tell you where the leak is, and it does not always mean the pipes are at fault. Automatic sprinklers, pool top-up valves, a rainwater tank topped up from the mains and a running toilet can all trigger it, so rule those out first.
The Toilet Dye Test
Toilets are a common source of silent leaks, because water can trickle from the cistern into the bowl without a sound. To test, add a few drops of food colouring to the cistern without flushing, wait about ten minutes, and check the bowl. If colour appears, the seal or valve is leaking. Flush afterwards so the colouring does not linger.
Where Leaks Hide in Perth Homes
In a typical home, hidden leaks tend to turn up in a handful of places. Underground pipes between the meter and the house can crack or separate at joints, and because they are buried, the water simply soaks away. Pipes running under or through a concrete slab are hard to reach and hard to inspect. Garden reticulation is another common culprit, with broken sprinkler lines and stuck valves wasting water out of sight.
Inside the house, look at the hot water unit and its connections, the cisterns and connections around toilets, and the pipes in wall cavities behind bathrooms and kitchens. Older pipework can corrode or fail at joints, while newer plumbing can be affected by poor fittings or movement. Any of these can leak slowly for a long time before the damage shows.
How Professionals Find Leaks Without Unnecessary Damage
The aim of modern leak detection is to pinpoint the problem before anyone picks up a jackhammer. Several methods are used, often in combination.
Acoustic listening: Sensitive microphones pick up the sound of water escaping from a pressurised pipe, and the loudest point on the surface indicates where to look.
Thermal imaging: A thermal camera shows temperature differences, which can reveal hot water leaks or damp areas behind surfaces without opening them up.
Moisture meters: These measure moisture in walls, floors and other materials, helping to map how far the water has travelled.
Pressure testing: Sections of pipework are isolated and pressurised to see whether the pressure holds, which tells the plumber which part of the system is leaking.
No single method suits every situation, and results can depend on pipe material, depth and background noise, which is why an experienced operator combines them and confirms the finding before any digging begins.
Water Corporation Leak Allowances and Insurance
The Water Corporation notes that once a licensed plumber has fixed a leak, it may be able to offer a leak allowance to help reduce your charges. At the time of writing, its leak allowance page says the allowance can be up to 50% of the estimated water lost, does not cover the cost of repairs, applies to hidden leaks repaired by a licensed plumber, and must be applied for within six months of the repair. Eligibility rules apply and can change, so read the page before you assume you will qualify, and keep your repair invoice and photographs.
Insurance is a separate question. Policies differ on what they cover for gradual or concealed leaks, so check your own policy document or ask your insurer before you rely on it.
What to Do the Moment You Suspect a Leak
Do not wait to see whether it sorts itself out, because leaks only get worse. Start by running the meter test and noting the reading with the date and time. Photograph any damp patches, stains or lifting paving so you have a record of how things look today.
If water is clearly escaping and you can find the stop tap at the meter, turning it off will stop the loss while you arrange help. Then book a licensed plumber with leak detection equipment, and keep the bills that prompted your suspicion, since they help show when the problem started.
Frequently Asked Questions
How do I know if I have a leak under my slab?
A meter that moves with everything switched off, a bill that has risen for no clear reason, damp or a musty smell, or a floor that feels warm in one spot can all point that way. Under-slab leaks cannot be confirmed by eye, so a professional inspection is the reliable answer.
How much water can a small leak waste?
It depends on the size of the leak, but even a slow one runs around the clock. The Water Corporation’s leak checking tool can estimate the water and money being lost once you enter your meter readings.
Will my home insurance cover a hidden leak?
It varies from policy to policy, particularly for gradual or concealed leaks. Read your policy or ask your insurer before you rely on it.
Is leak detection invasive?
Modern methods such as acoustic listening, thermal imaging and pressure testing are designed to locate a leak with minimal disturbance. Once the leak is found, the repair may still need access to the pipe, but the search itself does not usually mean opening up half the house.
Final Thoughts
A hidden leak is a slow drain on both your wallet and your home. Watch your bill, learn what your meter is telling you, and act on the signs early. When the checks point to a problem you cannot see, a licensed plumber with the right equipment can find it quickly and keep the repair as small as possible.






