Signs You Have a Water Leak at Home and What to Do About It

Water leaks are one of those problems that tend to be discovered either very early or far too late. The early ones are easy, like a dripping tap, a wet patch under the sink, something obviously wrong that gets fixed quickly. The ones that go undetected for months are the expensive ones. They sit inside walls, under floors or beneath concrete slabs, quietly causing damage until something visible finally gives them away.

By the time most hidden leaks show up, the water has usually been travelling through the structure of the building for a while. Timber rots. Mould establishes itself. Insulation gets saturated. In Perth's warm climate, these problems move faster than they would in cooler states, which makes early detection genuinely important rather than just good practice.

Here's what to look for and what to do if you think something is wrong.

Warning signs of a water leak

Some signs are obvious. Others are easy to dismiss until you know what you're looking at.

Unexplained rise in your water bill. This is often the first signal that something is wrong. If your water usage habits haven't changed but your bill has gone up meaningfully, it's worth investigating. The Water Corporation of WA has a useful leak detection guide on their website and can assist if you suspect a leak on the mains supply side of your meter.

The sound of running water when nothing is on. If you can hear water moving somewhere in the house when every tap, appliance and toilet is off, that's worth paying attention to. It's not always a leak — some sounds have other explanations — but it's not something to ignore.

Damp or musty smell in a room with no obvious cause. Water that's been sitting in a wall cavity or under a floor for any length of time develops a distinct smell. If a room consistently smells musty and there's no visible explanation, moisture is a likely cause.

Soft, stained or bubbling areas on walls or ceilings. Paint that's bubbling, plaster that feels soft to the touch or discolouration on a ceiling directly below a bathroom are all signs that water is getting somewhere it shouldn't be.

Mould appearing in unexpected locations. Mould in a shower recess is common and manageable. Mould appearing on an internal wall that isn't a wet area is a different situation and usually indicates moisture behind the surface.

Wet patches in the garden with no irrigation explanation. If a section of your garden is consistently wet or particularly green compared to the surroundings and you haven't been watering it, there may be a leak in an underground pipe. This is particularly common with older galvanised steel pipes, which Perth has a significant number of given the age of much of its housing stock.

Cracking in concrete paths or driveways near the house. Sub-slab leaks can cause soil movement that results in surface cracking. It's not a definitive sign on its own, but combined with other symptoms it's worth noting.

How to do a basic leak check at home

Before calling a plumber, you can do a simple check that confirms whether water is moving through your system when it shouldn't be.

Turn off every tap, appliance and the toilet cistern fill valve if you can. Go to your water meter — usually located near the front boundary of your property — and note the reading. Wait thirty minutes without using any water at all. Check the meter again.

If the reading has changed, water is moving through the system somewhere. That doesn't tell you where the leak is, but it confirms that something is happening and gives you a clear basis for calling a plumber.

The Water Corporation of WA has a step-by-step guide to reading your meter and checking for leaks that's worth looking at before you call anyone.

Who is responsible for the leak?

This is a question Perth homeowners and landlords frequently ask, and the answer depends on where the leak is located.

The Water Corporation of WA is responsible for the water main and the infrastructure up to your property meter. Everything on the house side of the meter — the pipes, fixtures and fittings within your property — is the homeowner's responsibility.

For rental properties, the Residential Tenancies Act 1987 (WA) is clear that landlords are responsible for maintaining the property in a reasonable state of repair, which includes the plumbing. The Consumer Protection division of DMIRS provides guidance on landlord and tenant responsibilities in WA, including what constitutes an urgent repair — and a burst or active leak generally qualifies.

Types of leaks and what causes them

Tap and fixture leaks. Usually a worn washer or O-ring. Straightforward to fix but easy to ignore. A dripping tap wastes more water than most people realise. The Water Corporation estimates that a single dripping tap can waste thousands of litres per year.

Toilet leaks. A toilet that keeps running or refills periodically without being flushed is leaking. Often caused by a faulty inlet valve or flapper. Easy to confirm by adding a few drops of food dye to the cistern and checking whether colour appears in the bowl without flushing.

Pipe leaks within walls. Caused by corrosion, joint failure, movement in the building or poor installation. Harder to detect and harder to fix — usually requires a licensed plumber to locate and repair.

Sub-slab leaks. Leaks in pipes that run beneath the concrete slab of the house. These are the most serious type, can cause significant structural issues over time and require specialist detection equipment to locate accurately. Perth has a large number of homes with older cast iron or galvanised pipes beneath the slab that are reaching the end of their service life.

Hot water system leaks. Pressure relief valves that drip constantly, corroded tanks and failing connections are all common. A hot water system that's leaking from the tank itself typically needs replacement rather than repair.

Plumbing licensing requirements in WA

All leak repair and plumbing work in Western Australia must be carried out by a licensed plumber registered with Building and Energy under the Plumbers Licensing Act 1995 (WA).

Most plumbing repairs also require the plumber to submit a Plumbing Notice to Building and Energy. This is a legal requirement, not optional, and a plumber who doesn't mention it is worth asking about directly.

DIY plumbing repairs are illegal in WA, void most home insurance policies and create real problems if they surface during a property sale. It's not worth the risk.

What to do if you find a leak

If water is actively flowing and causing damage, locate your mains water shutoff valve — usually near the meter at the front of the property — and turn it off. Then call a licensed plumber.

If the leak is less urgent, note what you've observed, do the meter check described above and call a plumber to investigate. Don't wait to see if it gets worse on its own. It generally does.

If you're a tenant, report the issue to your landlord or property manager in writing as soon as you notice it. Under the Residential Tenancies Act 1987 (WA), landlords are required to address urgent repairs promptly. The Consumer Protection division of DMIRS has clear guidance on what tenants can do if urgent repairs aren't addressed.

This & That provides leak detection and plumbing repairs across Perth for homeowners and landlords. Request a quote here or call 0487 606 491 to talk through what you're seeing.