Leak Detection Sydney

We find hidden water leaks in slabs, walls, ceilings, underground pipes and pool pipework, then repair them. For gas, our licensed gas fitters find and repair leaks the same day.

On this page: Our jobs · Signs of a leak · Sydney Water allowance · Questions

Leak detection jobs

Castle Hill: tracer gas finds a leak under a big tree

A customer’s water bill came in at five times the usual amount. We traced her water service, then used tracer gas to find the leak under a big tree. We repaired the pipework and helped her with the paperwork for Sydney Water’s hidden leak allowance.

Baulkham Hills: a gas smell that came and went

A gas smell kept coming and going. The leak turned out to be small, and we found it using nitrogen and our underground scanning equipment. Then we repaired it.

Reviews from leak customers

“We had a water leak underneath one of my properties in castle hill that was proving difficult to locate. Johnny came out, found the problem and repaired it properly. He was knowledgeable and professional throughout, and the quality of the work was outstanding”

Joshua B., Google review, 2026

“The team has been amazing! I had a leak and Alex was able to identify the issue with no fix required. I really appreciate the help. 10/10 service”

Leah A., Google review, 2026

What other customers say on Google

Signs of a hidden leak

• A water bill that has jumped even though the household uses water the same way.
• Wet patches on the lawn, or a strip of grass greener than the rest.
• Damp walls, bubbling paint, or a stain spreading on a ceiling.
• Water running somewhere with every tap turned off.
• Loose or cracked tiles around a shower, or a musty smell in a bathroom.
• A smell of gas, which needs action straight away. More on gas leak detection.

Check for a water leak yourself

Sydney Water suggests a simple meter test:

1. Turn off every tap and every appliance that uses water, including the dishwasher, the washing machine and any garden drippers.
2. Find the water meter. It’s usually just inside the front boundary. Leave the meter tap on.
3. Write down the numbers on the meter.
4. Leave all water off for an hour or more.
5. Check the numbers again. If they have changed, there is a leak.

How we find leaks

We use the methods that suit the job, so we open as little of the building as possible.

• Thermal imaging shows temperature differences on walls, floors and ceilings, which can point to water behind them. More on thermal imaging.
• Acoustic listening hears water escaping from a pipe under pressure.
• Pressure testing isolates sections of pipe to show which one is losing water.
• Moisture meters measure how wet a wall or floor is, and how far the damp spreads.
• Tracer gas finds leaks in pipes under slabs and paths, where other methods struggle.
• Underground scanning helps trace buried pipes and other services before we dig.
• Gas leak detectors follow a gas smell back to the fitting or pipe it comes from.

Leaks we find

• Under concrete slabs, in walls and in ceilings.
• In underground pipes between the meter and the building, including fire hydrant lines. More on water leak detection.
• Behind showers and tiles. More on shower leak detection.
• In pool pipework, including pressure tests on a new pool’s pipes before the concrete is poured. We don’t test pool shells or surfaces. More on pool leak detection.
• Gas leaks at appliances, fittings and gas lines, found and fixed today.

After the leak is found

We talk you through the cause and price the repair before we start. Where it can be done on the same visit, we fix it then. If the cause isn’t the plumbing, such as failed waterproofing, we tell you who to call.

Water from a hidden leak can damage floors, walls and ceilings, and damp areas can grow mould. The Insurance Council of Australia advises telling your insurer about water damage as soon as possible. Take photos before you move or throw out anything that is damaged, and ask us for a written report with photos.

Sydney Water’s hidden leak allowance

Once a licensed plumber or qualified technician has found and repaired a hidden leak, Sydney Water may credit part of your bill. Here is how it works:

• The credit is half the water usage charge for the worst-affected quarter.
• The leak must be hidden, one you didn’t know about and couldn’t see or hear. Visible leaks, such as dripping taps, toilet cisterns, appliances or damp soil, do not count.
• You must have maintained your water service.
• Apply within a year of the repair. Each property can get one allowance every five years.
• Only the owner or an authorised contact can apply, by phone.
• Sydney Water asks for the plumber’s business name, ABN, phone number and licence number, and the repair invoice. It also wants a photo of the meter reading after the repair.

Our invoice shows the business details Sydney Water asks for.

Before we arrive

• Note when you first saw the signs, and where.
• Have a recent water bill handy, so we can compare use.
• Clear access to the water meter and to the damp area.

Whose leak is it?

If you see water leaking in a public space, such as the street, report it to Sydney Water so it can investigate. Who fixes a leak depends on whose pipe or fitting is leaking, not only on where the water shows. If the leak is in your home or garden, Sydney Water’s advice is to call a licensed plumber. The pipes and fittings between Sydney Water’s main and your house belong to the property owner, and that includes the meter tap. The water meter itself is Sydney Water’s.

What does leak detection cost?

A weekday call-out, 7am to 5pm, is $0. The plumber looks at the signs and gives you a price for finding the leak. What affects that price is the type of leak, the methods needed and how easy it is to reach. The repair is priced separately, once we know what it involves.

Evenings, weekends and public holidays have a call-out fee of $275 to $385 with GST. You’ll know the amount before we leave for your place. Book online and $50 comes off any quote you accept.

Why All Day for leak detection

• Our contractor licence, 339748C, covers plumbing, drainage and gasfitting.
• Licensed gas fitters, so gas leaks are found and fixed on the day.
• Fully insured.
• 20+ years of experience behind every job.
• Repairs backed by our warranty.

Leak detection questions

Areas we cover

Our leak detection covers metropolitan Sydney, and we’re based in Seven Hills. In the Hills, our Hills District plumbers page covers the local suburbs. Every other suburb is listed on the locations page.