How to Tell If You Have a Hidden Water Leak

Honestly, a hidden leak is tricky because it's, well, hidden. Water can get loose inside a wall or under your slab and you won't see a single drop — but you will start noticing the effects. The real trick is knowing what those effects look like before things spiral.

The warning signs of a hidden leak

Because leaks happen in places you can't actually see — behind walls, underneath floors, buried in concrete — you're going to notice symptoms first. Here's what to watch for:

• A higher water bill that doesn't line up with what you're actually using. The Water Corporation amount creeps up but nothing about your routine has changed. This is honestly one of the most reliable early warnings you'll get.
• Damp patches or discolouration showing up on walls, ceilings or floors. Paint sometimes bubbles or starts peeling in odd spots too.
• Mould or mildew in a place that has no reason to be damp, or a musty smell that just won't shift no matter how much you air things out.
• Reduced water pressure because the pipe is losing water before it even reaches your tap.
• The sound of running water when every single tap and appliance has been switched off.
• Warm spots on the floor — possibly a hot water line that's leaking underneath the slab.
• Cracked or lifting tiles and patches of your lawn that suddenly look way greener than everything else, usually sitting right above where a pipe runs.

The water meter test (do this yourself)

You can actually confirm a leak pretty quickly with this one, and you won't need any tools at all. Just follow along:

• Turn everything off. Every tap, inside and out. Dishwasher, washing machine, irrigation — make sure nothing is running.
• Find your water meter. Around Perth it's typically up near the front boundary, often sitting inside a box in the ground. Write down the reading, including those small dials.
• Wait 1–2 hours and make sure you don't use any water during that time.
• Check the meter again. If the numbers have shifted, water is going somewhere it shouldn't be on your property.

Some meters have a little red or black leak indicator dial that spins even when just a trickle of water passes through. If that thing is turning while everything's off, you've basically got your answer. Not sure where your meter is? Our guide on finding and turning off your water mains walks you through the whole thing.

What to do while you wait to confirm

Sometimes the meter test is a bit inconclusive — the reading might have shifted only slightly, or you're second-guessing whether you read it right. Try running the test overnight when nobody in the house is using water. A leak becomes a lot more obvious over eight or ten hours. It also helps to eliminate the easy stuff first: double-check that a garden tap isn't dripping, make sure the reticulation controller hasn't snuck in a cycle, see that no appliance is quietly filling up somewhere in the background. Rule all that out, and you're likely looking at a genuine hidden leak — which is exactly the kind of thing professional detection is designed for.

Toilet leaks: the silent water waster

A toilet that's leaking can run through thousands of litres without ever producing a visible drip. To test yours, drop a few drops of food colouring into the cistern, then leave it alone for fifteen minutes without flushing. If colour shows up in the bowl, water is passing from the cistern through to the bowl and that seal or valve needs looking at. It's a straightforward toilet and fixture repair that more than pays for itself.

Common places hidden leaks happen

Leaks have favourite spots, and knowing what they are helps you catch things early. Around Perth these are the usual suspects:

• Under the slab. Pipes buried in or below the concrete can leak quietly for months — you might notice a warm patch on the floor or a bill that makes absolutely no sense.
• Inside walls. Joints behind plaster weep slowly, causing damp and bubbling paint long before any actual water shows up on the surface.
• Under sinks and vanities. Seals wear out, fittings work loose, and drips collect inside cabinets you probably don't check all that often.
• At the hot water system. A tank or connection starting to go will often leak slowly at the base.
• In the irrigation or reticulation system. Underground garden lines are honestly one of the most common causes of a mysterious usage spike.

Why hidden leaks matter

It isn't just the bill. A leak left to its own devices will cause real damage:

• Structural damage to timber, plaster and flooring
• Mould that messes with air quality and health
• Damage to your home's foundations or slab
• Wasted water — and in WA's climate that actually matters

Finding it sooner means a smaller repair. A slow leak caught this month is a patch job; the same leak left for a year could mean ripping out flooring and cabinetry.

How professional leak detection works

Once you know there's a leak, the tricky part is pinning it down without tearing up walls or floors. That's where professional water leak detection earns its keep. Licensed plumbers come in with non-invasive gear — acoustic listening equipment, thermal imaging, pressure testing — to work out the exact spot. The repair stays targeted and minimal, no exploratory demolition required.

If the leak turns out to be a cracked or corroded pipe, it can be sorted before it turns into a burst pipe situation and a far bigger headache.

When to call a plumber

Get a licensed plumber involved if your meter test shows water is moving with everything off, your bill has jumped without explanation, or you're seeing damp, mould or warm spots you can't account for. Trying to track down a hidden leak on your own usually just means unnecessary holes in walls — professional detection finds the thing fast and keeps the fix small.

Think there's a leak you can't find? Call our licensed Canning Vale plumbers and we'll track it down without wrecking your house.

Frequently asked questions