8 Warning Signs You May Have a Hidden Water Leak

A water leak isn’t always an obvious burst pipe or dripping tap. Many leaks develop out of sight, quietly causing structural damage, inviting mould, or driving up water bills. These hidden leaks can lurk behind walls, under floors, or within slab foundations—going undetected for months.



Whether you’ve recently noticed musty odours or your water meter’s spinning when no one’s using water, there’s usually a silent culprit behind it. Understanding the early signs of a hidden leak is critical to avoiding serious—and expensive—plumbing damage. Here’s how you can spot the warning signs of a water leak and what to do about them.

1. Unexplained Spikes in Your Water Bill

An unexpectedly high water bill is often the first red flag. If your water usage habits haven’t changed but your costs have, it’s time to investigate further.

Unseen leaks—especially in underground pipes or within wall cavities—can allow hundreds of litres to seep away daily. Unfortunately, many property owners don’t notice until the bill arrives.

Some signs your water bill could be leak-related:

• There’s no increase in household water usage, but your bill has risen sharply
• Water meter readings show continuous usage overnight
• You’ve ruled out appliances like dishwashers or irrigation systems as the cause

Ignoring these signs risks wasting water and money. A licensed plumber can perform detailed leak detection to pinpoint the issue.

2. Damp Patches on Walls or Floors Aren’t Just Cosmetic Issues

Have you noticed a soft patch in the carpet? Perhaps a stain on the wall that wasn’t there last month? These are often early visual cues that water escapes somewhere it shouldn’t be.

While rising damp can come from outside, leaks from interior plumbing can create similar symptoms.

Watch out for:

• Bubbling or peeling paint on interior walls
• Floorboards lifting or warping unexpectedly
• Persistent wet spots that return after cleaning or drying



If the area is warm to the touch, the leak might come from a hot water line—another job for a plumber with thermal imaging capabilities.

3. The Sound of Running Water When Taps Are Off Shouldn’t Be Ignored

It’s one of the most overlooked signs—hearing water trickling, dripping or hissing when every tap is tightly shut. These sounds usually indicate water is escaping inside the walls or under the slab.



This is especially concerning if:

• You hear faint hissing or dripping at night when the house is quiet
• The toilet isn’t running, but water sounds persist
• You suspect the leak may be under concrete or tile flooring

Acoustic leak detection can isolate the sound source, even if it’s buried deep in the structure.

4. Mould & Mildew Growth Can Signal Moisture from Hidden Leaks

Finding mould in places that should remain dry—like behind cabinets, wardrobes, or in corners of bedrooms—often points to excess moisture caused by a leak.

Mould spores thrive in damp, dark spaces and multiply quickly when water is present. Left untreated, this can create a structural issue and a serious health concern.

Warning signs of water-leak-induced mould:

• Musty smells in otherwise dry areas of the house
• Recurring black or green spots on walls or ceilings
• Mould growth in rooms with no plumbing fixtures



Professional plumbing services can trace the water’s source and recommend remediation.

5. Water Meter Changes Without Usage Point to Plumbing Issues

A simple meter test can often confirm whether you have a hidden leak. It’s a fast, DIY-friendly method before calling a plumber.

Follow these steps:

• Turn off all water usage in the house (including irrigation systems and appliances)
• Locate your water meter and record the current reading
• Wait 30–60 minutes without using any water
• Recheck the meter. If the numbers have changed, water is leaking somewhere in your system

Even a small drip can show up over a short testing window, alerting you to call for leak detection services.

6. Leaks may cause Foundation Cracks or Shifting Floors

Sometimes the signs of a hidden water leak aren’t indoors. Foundation movement, cracking tiles, or shifting flooring can all result from prolonged exposure to moisture beneath the home’s slab.

Water slowly escaping from pipes under the slab can erode soil, compromise footings, and lead to expensive repairs.

Look out for:

• Visible cracks in foundation walls or floor slabs
• Uneven or sagging sections of flooring
• Doors and windows sticking or misaligning over time

This kind of damage can escalate if not addressed. Learn more about how undetected leaks affect your home’s structure here.

7. Low Water Pressure Might Be the Result of a Hidden Pipe Leak

Low water pressure is commonly dismissed as a local supply issue, but it could be more serious when it persists only in your home.

Leaking pipes can divert flow before it reaches your taps, meaning you get a trickle instead of a stream. Over time, this can worsen and affect multiple areas.

You may notice:

• Poor flow from taps or showerheads in specific rooms
• Reduced pressure only on the hot or cold side
• The issue getting worse, not better, over time

A professional plumber can assess your plumbing system for pressure irregularities and identify leaks through pressure testing or thermal imaging.

8. Warm Spots on the Flooring Could Mean a Hot Water Pipe Is Leaking

One of the more subtle signs of a hidden leak is warm floorboards or tiles in unexpected areas. If you walk barefoot and notice heat in places away from underfloor heating or appliances, it could be a hot water leak under the slab.

Watch for:

• Isolated warm or spongy sections of flooring
• Condensation on floors in non-humid environments
• A continuous need to reheat water due to system inefficiency

Thermal imaging technology used by plumbers can quickly confirm and locate this kind of leak without unnecessary excavation.

Book Professional Leak Detection in Tamworth Today

At ACS Plumbing, we detect and repair hidden water leaks with precision. If you’ve noticed any of the signs mentioned above, don’t wait until the damage becomes visible—and expensive. Our licensed plumbers in Tamworth can inspect your property, carry out leak detection, and provide the right repairs to protect your home’s integrity.

Book our leak detection services today. For tailored advice or to book a consultation, get in touch via our contact page.