How do I know if I have a hidden water leak?

Signs include unexplained rises in water bills, damp patches on walls or ceilings, mould without an obvious source, the sound of running water when nothing is on, and low water pressure.

How does ATC Plumbing detect hidden water leaks?

We use acoustic detection equipment and thermal imaging to locate leaks without unnecessary cutting or excavation.

How much does leak detection cost in Melbourne?

Water leak detection in Melbourne typically costs between $200 and $500 depending on the property size and leak complexity.

Hidden Water Leaks: 5 Signs You Need Leak Detection

Christopher Unwin
Apr 20, 2025
2 min read

Updated: May 3

5 Signs You Have a Hidden Water Leak

Hidden water leaks can cause significant structural damage and mould growth before you're even aware they exist. Here are the five most common warning signs.

1. Unexplained Increase in Your Water Bill

If your water bill has jumped without any change in your household's usage patterns, water is going somewhere it shouldn't be. Compare bills quarter-on-quarter — a consistent upward trend without obvious explanation is a strong indicator of an underground or concealed leak. Even small leaks waste hundreds of litres per day.

2. Wet or Soggy Patches in the Garden

A patch of lawn or garden that's consistently wetter than surrounding areas — particularly in dry weather when you haven't been watering — suggests an underground supply pipe leak beneath it. Lush green patches in an otherwise dry garden are another indicator. Tree roots often accelerate toward these areas, causing secondary damage.

3. Sound of Running Water

If you can hear water running inside walls, under floors, or underground when all taps and appliances are off, there's likely an active leak somewhere in your pipe system. Conduct the meter test to confirm: turn off all water outlets and watch the meter — if it's still moving, you have a leak.

4. Staining, Mould, or Dampness Inside Walls

Water stains on walls or ceilings, damp or musty smells in rooms with no obvious source, or mould growth in areas that shouldn't be wet are all signs of a concealed leak — often from supply pipes inside walls or roof plumbing. These leaks need to be found and fixed quickly to prevent structural damage and mould remediation costs.

5. Low Water Pressure Throughout the House

A gradual reduction in water pressure across multiple outlets can indicate a leak in the main supply line — water that should be reaching your taps is escaping through a breach in the pipe. If pressure has dropped noticeably, have a plumber assess your supply line. Call ATC Plumbing on 1300 282 758 for professional leak detection across Melbourne's south-east.