03 9888 2887
How to Find a Water Leak: Inside Walls, Underground, and What It Costs in Melbourne
Knowing how to find a water leak early can save you thousands. Left undetected, even a slow drip can saturate wall cavities, rot structural timbers, and create the kind of mould damage that takes months to fix. The problem is that most leaks aren’t visible — they’re behind plasterboard, under concrete slabs, or buried a metre underground.
Here’s how to spot one, what a plumber does to locate it, and what you can expect to pay.
Signs You Might Have a Water Leak
Before you start searching, know what you’re looking for:
- Water bills that have climbed without any change in usage
- Damp patches, bubbling paint, or soft spots on walls or ceilings
- Mould in areas that shouldn’t be wet
- The sound of running water when all taps are off
- Low water pressure throughout the house
- Warped or discoloured flooring
One of the most reliable checks: turn off every tap and appliance in the house, then watch the water meter. If the dial is still moving, water is escaping somewhere.
How to Find a Water Leak Inside a Wall
Wall leaks are difficult because the source and the visible damage are rarely in the same place. Water travels along pipes and timbers before it saturates enough to show on a surface — which means a damp patch on your ceiling might trace back to a pipe in the wall two metres away.
Start by checking for:
- Damp or discoloured patches that weren’t there before
- Peeling paint or bubbling wallpaper
- A musty smell concentrated in one room or corner
Pinpointing the exact location requires moisture meters or thermal imaging cameras — tools that detect temperature differences and moisture levels through plasterboard without cutting into it. This is where a licensed plumber with the right equipment will save you significant time and unnecessary wall damage.
How to Find a Water Leak Underground
Underground leaks are harder to spot, but they do leave signals. To tell if you have a water leak underground, look outside for:
- Unexplained wet patches or boggy ground in the yard with no recent rain
- Cracks forming in your driveway or paths
- A section of lawn or garden that’s noticeably greener than the rest
- A drop in water pressure that can’t be explained by anything inside
To confirm it, turn off all water inside and outside the property and take two meter readings an hour apart with nothing running. If the reading changes, water is escaping — and underground is the likely culprit.
How Does a Plumber Find a Water Leak Underground?
Plumbers use a variety professional leak detection methods to find a water leak underground, depending on the pipe depth, type, and access.
At O’Shea Plumbing, our plumbers use acoustic listening equipment to detect the sound of water escaping from pressurised pipes beneath the ground. We also use thermal imaging and Testo moisture meters to identify wet zones without excavation.
For more complex jobs — particularly older iron pipes in established Melbourne suburbs — CCTV pipe inspection lets us see inside the line before any digging starts. That means we can confirm the exact fault location and avoid unnecessary damage to your driveway, garden, or paving.
How Much Does Leak Detection Cost?
Leak detection costs in Melbourne vary depending on access, pipe depth, and the complexity of the system. A visible above-ground leak inspection costs less than a job involving underground mains or in-slab pipes. Most licensed plumbers will assess the situation and quote before any work begins.
The more relevant number: catching a leak early almost always costs less than the damage it causes if you wait. Mould remediation, timber replacement, and concrete reinstatement add up quickly — and none of it is covered by standard home insurance once it’s clear the leak was gradual and long-running.
Our water leak detection team at O’Shea Plumbing has been working across Melbourne for over 48 years. We carry out all work to AS/NZS 3500 standards and operate 7 days a week.
Suspect a leak? Call us on 03 9888 2887.
