How do you find a water leak underground? 

Noticing a dripping tap or a burst pipe under the sink is easy, but not all leaks manifest in the same way. 

Finding an underground water leak early can prevent serious property damage and unexpected water bills.

You can find an underground water leak by performing a water meter test and checking for physical signs such as soggy patches, low water pressure, or unusually green grass. If the leak is not visible, professional leak detection equipment may be required.

One drip may not look like much at first, but over time, small drips can accumulate into a big problem. 

A leaking tap can waste up to 10,000 litres of water a year, while a running toilet cistern can waste around 9,000 litres. 

If you suspect a leak in your home or business, this guide will help you identify warning signs and locate the source. 

How to check for an underground water leak using your water meter

Before looking for visible signs of an underground water leak, let’s first confirm if you even have a potential water leak on the property. One of the most effective ways to detect a water leak is to check your water meter. 

You can use the Water Corporation’s online leak detection tool to check whether your property may have a hidden water leak. By entering your water meter readings, the tool helps calculate potential water loss and determine if further investigation is needed.

Follow these steps:

• 1) Turn off all taps, appliances, and irrigation systems.
• 2) Locate your water meter.
• 3) Record the three red numbers on the meter.
• 4) Enter those numbers into the Water Corporation leak detection tool.
• 5) Wait 15 minutes without using any water.
• 6) Recheck the three red numbers and enter the updated reading into the tool.

If the numbers have changed, it may indicate a leak on your property.

Common signs of an underground water leak

If your water meter test suggests there may be a leak, the next step is to look for signs around your property. Underground leaks can show warning signs before they become massive problems. 

Unexplained increase in your water bill 

An increase in your water bill is most often the most obvious sign that you may have a leak on your property, especially if your water usage habits have not changed over time. 

Below is a table showing the average monthly water usage and estimated costs for households of different sizes in Australia.

Average Water Usage & Costs by Household Size (Australia)

If you’re unsure whether your water bill is higher than it should be, you can use this table as a rough guide to determine whether you are spending more than the average. 

If your usage is noticeably above these averages without a clear reason, you may have a hidden leak on your property.

Soggy or damp patches in the garden 

If you have noticed wet, muddy or constantly damp areas in your garden, this may indicate a leaking underground pipe. 

Lush, greener patches of grass 

If a section of your garden looks healthier and greener or grows faster than the rest, that area may be receiving more water, indicating a leak. 

Low water pressure 

If you’ve noticed your shower pressure has dropped or your sink has less running water, this could indicate a leak in your home. 

Hissing or running water sounds 

Hearing running water throughout your property when all taps and appliances are off could indicate a hidden leak.

Cracks in the driveway or paving 

Persistent underground leaks can soften soil, causing soil to shift, sink, or crack, leading to cracks in concrete, paving, or even foundations.

When to call a professional leak detection plumber

Many small leaks can be identified using your water meter or by simply spotting them, but underground leaks can be hard to find without specialised equipment. 

If you’ve done the water meter test and confirm you have a water leak but can’t locate the leak, it might be time to call a licensed plumber. 

You should give your local plumber a call if: 

• Your water meter continues to run when all taps and appliances are turned off.
• You notice soggy patches, pooling water, or unusually green areas in your garden.
• Your water bill has increased significantly without a change in usage.
• You suspect the leak may be under concrete, paving, or your home’s slab.
• You hear running water but cannot find the source.
  

Many professional plumbers use advanced leak-detection equipment, such as acoustic listening devices, pressure testing, and thermal imaging, to locate leaks without tearing up your garden or property. 

Also, using a licensed plumber allows them to respond quickly to prevent further property damage, reduce water waste, and save money on unused water and repairs a leak may cause. 

How professionals find underground water leaks

Professional plumbers use specialised equipment to accurately locate underground water leaks without unnecessary digging. 

Acoustic Leak Detection

Acoustic listening devices and ground microphones detect the sound of water escaping from pressurised pipes beneath soil, concrete, or paving. This helps pinpoint the leak location with precision.

Pressure Testing

Pressure testing determines whether a section of pipe is leaking and helps isolate the affected area before any digging begins.

Tracer Gas Detection

In more complex cases, a safe tracer gas is introduced into the pipe system. Technicians then use sensitive detection equipment to pinpoint the exact location of the gas leak at ground level.

How to apply for a leak allowance in WA

If you’ve had a hidden leak fixed or think you might have a leak, you may be eligible to apply for a leak allowance with the water Corporation. 

A leak allowance is a credit you might be able to receive on your water account if you’ve had a hidden water leak on your property that led to unusually high water usage. It is designed to help reduce the cost of the extra water lost due to the leak. 

You may receive a credit of up to 50% of the estimated water loss resulting from a hidden leak. Please note that the allowance does not cover the cost of repairing the leak itself or any plumbing services. 

For more information on how to apply for a leak allowance, visit the Water Corporation website. 

Suspect an Underground Water Leak?

If your water meter test signals a leak, or you’ve noticed warning signs around your property, professional leak detection can stop further damage and unnecessary water loss.

Early detection reduces repair costs and protects your home’s foundations and landscaping.

Frequently asked questions

Is there a tool to find a water leak underground?

Yes. Professional plumbers use specialised leak detection equipment to locate underground water leaks without unnecessary digging.

Common tools include:

• Acoustic listening devices that detect the sound of escaping water.
• Ground microphones that amplify leak noise.
• Pressure testing equipment.
• Thermal imaging cameras.

These tools allow plumbers to pinpoint the exact location of a leak beneath soil, concrete, or paving.

How to determine where an underground water leak is coming from?

To determine the source of an underground water leak:

• Turn off all taps and water appliances.
• Check your water meter to confirm it is still running.
• Inspect your yard for soggy patches, pooling water, or unusually green grass.
• Listen for hissing or running water sounds when everything is turned off.
• Arrange for professional leak detection if the source is not visible.

An accurate location usually requires specialised equipment to avoid unnecessary excavation.

How to trace the source of a water leak?

Tracing the source of a water leak involves isolating sections of plumbing to identify where water loss is occurring.

Plumbers may:

• Perform pressure tests on different pipe sections.
• Use acoustic detection equipment.
• Inject tracer gas into pipes to locate escaping gas at the surface.
• Conduct CCTV pipe inspections.

This method ensures the exact leak location is identified before any digging begins.

Can I use my phone to detect underground water?

No, a standard smartphone cannot reliably detect underground water leaks.

Some apps claim to measure sound frequencies, but they are not accurate enough for underground detection. Professional acoustic equipment is far more sensitive and designed specifically for leak detection.

How much does it cost to have a leak detected?

In Australia, professional leak detection typically costs between $300 and $800, depending on:

• Property size.
• Leak location.
• Accessibility.
• Equipment required.

Complex cases involving slab leaks or deep underground pipes may incur higher costs.

How deep are most residential water lines?

Most residential water lines in Australia are installed at depths of approximately 300mm to 600mm below ground level.

Depth can vary depending on:

• Local council regulations.
• Soil type.
• Climate.
• Property layout.

Deeper installations may occur under driveways, slabs, or areas requiring additional protection.