Spotting Hidden Plumbing Leaks Before They Cause Damage

Slow-draining showers, leaking taps or suspicious noises coming from your pipes offer visible clues it's time to call in a professional plumber.

The problem comes when hidden leaks that you can't spot arise. Hidden plumbing leaks that go unnoticed can cause mould growth, structural damage, and skyrocketing water bills. Make no mistake, a small drip behind a wall or under the floor might not seem important—until it leads to costly repairs.

Some of the most expensive callouts we receive are a result of hidden leaks.

The good news? There are warning signs you can watch for, and in this guide, we’ll walk you through the telltale signs of hidden leaks and what to do if you suspect you have one in your home.

Why Hidden Plumbing Leaks Are a Problem

Hidden leaks are, by nature, out of sight and, over time, can cause serious damage. At the lower end of the damage scale is mould growth, but even this can be harmful, especially toxic black mould, that affects indoor air quality. It can also be especially harmful to people with respiratory issues, weakened immune systems, and other health problems such as asthma.

There's also the financial toll of hidden water leaks. Over time, these leaking pipes add up, and we're not just talking about wasting our most precious resource of water, but your utility bills, too.

It's the excess water leaking over time that leads us to the top end of the damage scale—water damage in your home. Besides issues like mould growth, water damage can result in structural weakening, and ruined flooring or walls. These are costly repairs and the longer a leak persists, the worse the damage becomes, which means that early detection is of the utmost importance for protecting your home and finances.

Signs You Might Have a Hidden Plumbing Leak

Here's what to watch out for to catch those sneaky hidden leaks.

Unexplained Increases in Water Bills

Track your water bills. It's useful to know your average cost so that when you suspect one has increased without a valid reason, you can compare it against previous bills. Additionally, check your water meter—if it’s still moving when no water is running, you’ve likely got a leak somewhere.

Water Stains and Discolouration

At some stage in your rental or home-owning life, you've probably noticed yellow or brown stains on ceilings, walls, or baseboards. Besides being unsightly, they’re often a sign of a slow leak behind the surface. It's worth nipping in the bud before becoming a bigger, more serious issue.

Musty Smells and Mould Growth

One step up from the discolouration on surfaces is seeing mould patches, especially in bathrooms or near pipes. It likely means hidden moisture issues. You may also notice a musty smell from drains, which means long-term exposure could also lead to health problems. You will want to address this one promptly.

Peeling Paint or Wallpaper

When you see your paint or wallpaper bubbling or peeling, it's not always just a case of a new paint job required. It could also be a sign of excess moisture behind the wall which has slowly soaked through from a leaky pipe somewhere above. Over time, this can cause serious water damage, weakening the drywall and leading to costly repairs.

Sound of Running Water When No Fixtures Are On

Have you ever heard water running when no taps are in use? It could mean water is escaping somewhere in your walls or under the floor. Don’t panic, but don't ignore it either—it could be causing damage where you can’t see it.

How to Detect Hidden Leaks

There are a few DIY plumbing steps you can take to detect hidden leaks before emergency plumbing is required.

DIY Leak Detection Techniques

Try these simple tests to catch a hidden leak before it becomes a major problem:

• The Water Meter Test – Turn off all water in your home, then check your water meter. If it’s still moving, there’s a leak somewhere.
• Food Colouring Test – Drop some food colouring into your toilet cistern and wait 10–15 minutes. If the colour seeps into the bowl without flushing, your toilet plumbing has a silent leak.
• Use a Moisture Meter – If you suspect a leak behind walls or under flooring, a moisture meter can help detect hidden damp spots before visible damage appears. You can buy these from Bunnings and other hardware stores.

Check Your Garden’s Irrigation Systems – Look for soggy patches and unusually high water usage.

When to Call a Professional Plumber

The advantage of calling in a professional Sydney Eastern suburbs plumber is that they use advanced tools like infrared cameras, pressure tests, and acoustic sensors to track down and fix leaks without tearing into your walls. Plus, they will find every leak and have it fixed promptly, including tap repairs.

Moreover, professional leak detection can save you time, money, and unnecessary damage.

Preventing Future Plumbing Leaks

We always advise that prevention is the best measure, and there are also steps you can take to keep your plumbing in check:

• Inspect Exposed Pipes Regularly – Check what you can see, the visible leaks under sinks, in basements, and around appliances for any signs of corrosion, moisture, or small leaks.
• Monitor Water Pressure – High water pressure can strain your pipes over time. Use a pressure gauge to ensure your plumbing systems within a safe range (typically 40–60 psi).
• Install Leak Detection Sensors – Smart leak detectors can alert you to moisture buildup before you even notice a problem, helping prevent water damage. You can pick these up from Bunnings and other hardware stores, or have a qualified plumber install them for you.
• Schedule Annual Plumbing Maintenance – The absolute best prevention measure you can take is hiring a professional plumber who is trained to spot potential issues early, saving you from costly repairs down the line.

Time to Take Action Against Your Water Leak?

Tackle those hidden plumbing leaks before they lead to serious damage and higher water bills. Look for the early warning signs—water stains, musty smells, or unexplained water usage. While regular maintenance and leak detection tools can help, sometimes you'll require a professional look.

Don’t wait until a small leak becomes a big problem. Stay proactive and protect your home. Contact Plumberoo today for a professional inspection, friendly service and expert plumbing solutions

Frequently Asked Questions

How long can a water leak go undetected?

A water leak can go undetected for weeks or even months, depending on its location and drip flow rate.

Can a water leak under the house cause damage?

Yes, a leak under the house can cause significant water damage, including, foundation damage, mould growth, and structural issues.

How do plumbers detect hidden leaks?

Plumbers use infrared cameras, pressure tests, and acoustic sensors to detect hidden leaks.

Can a small leak cause damage?

Even a small leak can lead to water damage, mould growth, and increased water bills.