How to Tell If You Have a Hidden Water Leak in Your Home

A leaking tap or burst pipe is usually easy to spot. A hidden water leak can be much harder to find.

Water can escape from pipes behind walls, beneath floors or underground without producing an obvious puddle. In some cases, the first indication something is wrong is an unusually high water bill, a damp patch that keeps returning or the sound of water running when nothing is turned on.

Finding a hidden leak early can help reduce wasted water and limit potential damage to your home.

In this guide, we explain the common signs of a hidden water leak, how you can perform a simple water meter test and when it is time to call a licensed plumber.

What Is a Hidden Water Leak?

A hidden or concealed water leak occurs when water escapes from pipework or plumbing that isn't readily visible.

Unlike a dripping tap, the source may be behind a wall, underneath flooring, inside cabinetry or underground between your water meter and your home.

The Queensland Government describes a concealed leak as a leak hidden from view, such as a broken or cracked water pipe underground or within a wall.

Because the water may be escaping slowly or somewhere you cannot see, a concealed leak can continue for some time before it becomes obvious.

7 Signs You May Have a Hidden Water Leak

No single symptom automatically means you have a leaking pipe. However, if you notice one or more of the following signs, it is worth investigating further.

1. Your Water Bill Has Suddenly Increased

An unexplained increase in water usage is one of the most useful warning signs of a hidden leak.

If the number of people living in your home and your normal water usage haven't changed significantly, but your consumption has increased, water may be escaping somewhere on the property.

In fact, the Queensland Government notes that a higher-than-normal water bill may be the first sign of a leak if you aren't regularly checking your water meter.

Before assuming there is a plumbing problem, consider whether there is another reasonable explanation for the increase, such as additional occupants, increased garden watering or other changes in household water use.

If nothing has changed, it is worth checking for a leak.

2. Your Water Meter Moves When Nothing Is Using Water

Your water meter can help you determine whether water is still flowing through your property's plumbing when it shouldn't be.

If every tap and water-using appliance is turned off but the meter continues recording consumption, there may be a leak somewhere on the property.

We'll explain how to perform a basic water meter test below.

3. Damp or Discoloured Areas Appear on Walls or Ceilings

Water escaping behind a wall or above a ceiling can eventually become visible on the finished surface.

Possible warning signs include:

• Brown or yellowish water stains

• Damp patches that don't seem to dry

• Bubbling or peeling paint

• Swollen plasterboard

• Warped skirting boards or cabinetry

However, moisture doesn't always mean a plumbing pipe is leaking. Roof leaks, condensation and failed waterproofing can produce similar symptoms, so finding the actual source is important before repairs begin.

4. You Can Hear Water Running When Everything Is Turned Off

If the house is quiet and you can hear dripping, hissing or the sound of water flowing when nobody is using a tap, shower, toilet or appliance, investigate further.

First check obvious fixtures such as toilets and taps.

If you can't identify where the sound is coming from, there could be water escaping somewhere within the plumbing system.

5. You Notice Unexplained Damp Areas Outside

Not every hidden leak occurs inside the house.

The water supply pipe running between your meter and home is generally underground, which means a leak can develop without being immediately visible.

Potential signs include an area of lawn that remains unusually wet, soft or greener than its surroundings, particularly during otherwise dry conditions.

Pooling water or persistently damp soil without an obvious explanation may also warrant investigation.

6. Your Water Pressure Has Dropped

A noticeable reduction in water pressure can sometimes occur when water is escaping from the plumbing system before reaching your fixtures.

However, low water pressure has several possible causes and doesn't necessarily mean you have a leak.

If you've noticed a sudden pressure change alongside other symptoms, such as unexplained water usage or damp areas, it is worth having the plumbing checked.

7. There Is a Persistent Damp or Musty Smell

Moisture accumulating in enclosed spaces can sometimes create a persistent damp or musty smell.

You might notice this inside a bathroom cabinet, laundry, under a sink or in a room adjoining plumbing fixtures.

Don't rely on smell alone to diagnose a leaking pipe. Moisture can also result from condensation, ventilation issues, roof leaks or waterproofing problems. However, a persistent smell accompanied by staining or dampness should not be ignored.

How to Check Your Home for a Hidden Water Leak

If you suspect a leak but can't see where it is coming from, your water meter is a good place to start.

The Queensland Government recommends the following basic process:

1. Turn off taps and make sure nobody will use water during the test.

2. Make sure water-using appliances such as washing machines and dishwashers aren't running.

3. Find your water meter and record the reading.

4. Don't use any water for at least one hour.

5. Check the meter again.

If the reading has changed despite no intentional water use, water is flowing somewhere on the property and you may have a leak.

Before assuming there is a concealed pipe leak, check obvious sources such as toilets, taps, showers and the hot water system.

If you still can't identify where the water is going, it may be time to have the plumbing investigated.

Don't Forget to Check Your Toilets

A leaking toilet can use water continuously without producing the type of visible leak most homeowners expect.

Sometimes you can hear the cistern continually refilling or see water moving into the bowl. Other leaks are less obvious.

The Queensland Government recommends checking toilets when investigating unexplained water consumption. One method is to add a small amount of food colouring to the cistern and see whether the colour enters the toilet bowl without flushing.

If it does, components inside the cistern may require attention.

Checking toilets first can help rule out a relatively common source of unexplained water usage before investigating concealed pipework.

Where Do Hidden Water Leaks Commonly Occur?

Hidden leaks can occur anywhere water supply pipes and plumbing fixtures are installed.

Areas worth investigating include:

• Behind bathroom and kitchen walls

• Under sinks and inside cabinetry

• Around toilets

• Behind washing machines and dishwashers

• Around hot water systems

• Beneath floors or concrete

• In underground water supply pipes

• Around outdoor taps and irrigation connections

It’s also important to distinguish a leaking water pipe from a drainage problem. Pooling water, unusual smells, gurgling fixtures or water backing up around sinks, showers or outdoor drains may instead indicate a blockage or damaged drainage pipe. If you’re noticing these symptoms, learn more about our blocked drains services in Brisbane.

The location of the visible moisture isn't always the location of the leak. Water can travel along pipes, framing or other building materials before appearing elsewhere.

This is one reason finding concealed leaks can sometimes require professional testing rather than simply opening the wall where a stain has appeared.

What Should You Do If You Think You Have a Hidden Leak?

Start by checking the obvious possibilities and performing the water meter test.

If the meter indicates ongoing water consumption but you can't identify the source, a licensed plumber can investigate the plumbing system and determine what is causing the water loss.

For a significant leak, shutting off the property's water supply may help limit further water loss until the problem can be assessed.

Avoid cutting into walls, floors or underground pipework yourself simply because you suspect where the leak might be. The visible symptom and actual source of a leak aren't always in the same location.

Queensland plumbing regulations also require regulated plumbing and drainage work to be carried out by appropriately licensed plumbers and drainers.

Who Is Responsible for a Water Leak in Brisbane?

It depends on where the leak occurs.

For homeowners, plumbing and fittings on the property side of the water meter connection point are generally the property owner's responsibility.

For Brisbane residents, Urban Utilities manages the water and wastewater network and is the organisation to contact for issues such as burst water mains and network water leaks.

If the leak is within your private plumbing, you will generally need a licensed plumber to investigate and repair it.

If you're unsure whether a problem is part of your private plumbing or the external water network, Urban Utilities can provide further guidance.

Can You Get Help With a High Water Bill Caused by a Concealed Leak?

Potentially.

Queensland has arrangements that may provide eligible customers with some relief where a concealed leak has resulted in unusually high water charges.

Eligibility requirements apply, so don't assume every leak or high water bill will qualify.

If you discover a concealed leak, keep records of the problem and any plumbing repairs and contact your water service provider to find out whether you may qualify for a concealed leak remission.

When Should You Call a Plumber?

You don't necessarily need to call a plumber because you've noticed one unusually high water bill or a small damp patch.

However, professional investigation is sensible when:

• Your water meter records usage while everything is turned off

• Your water consumption has increased without explanation

• Damp patches continually return

• You can hear running water but can't find the source

• You suspect an underground or concealed pipe is leaking

• Water is damaging walls, ceilings, flooring or cabinetry

• You have a substantial or active leak

The sooner the source is identified, the sooner you can stop unnecessary water loss and address any plumbing problem before it causes further damage.

Suspect a Hidden Water Leak in Your Brisbane Home?

Hidden water leaks aren't always obvious, but changes in your water usage, damp areas, unusual sounds and movement at the water meter can provide important clues.

If you've completed the basic checks and still can't determine where the water is going, MSV Plumbing Services can help investigate the problem and identify the source.

We provide plumbing services across Brisbane and can assess leaking or damaged pipework, plumbing fixtures and other potential sources of unexplained water loss.

Think you may have a water leak? Contact MSV Plumbing Services to arrange an inspection.

Sources & Further Reading

The following official resources provide additional information about water leaks, plumbing responsibilities and licensed plumbing work in Queensland:

• Queensland Government – Leaks: Guidance on identifying household leaks, performing a water meter test, concealed leaks and homeowner responsibilities.

• Brisbane City Council – Water Supply and Sewerage: Information about Brisbane's water supplier, water and sewerage leaks and who to contact for problems on private property or the network.

• Queensland Building and Construction Commission – Plumbing Problems: What Queensland Homeowners Need to Know: Information about regulated plumbing work and using appropriately licensed plumbers in Queensland.

• Queensland Government – Plumbing Laws: Information about plumbing requirements, licensed plumbers and notifiable plumbing work in Queensland.

This blog article was written by Matthew Main, Founder and Lead Plumber at MSV Plumbing Services.

Disclaimer:The information provided in this article is intended for general informational and educational purposes only. It does not constitute definitive technical, legal, or plumbing advice for any specific property or situation. While managing minor plumbing inconveniences can sometimes wait, active burst pipes, structural leaks, and sewage overflows present serious property damage, electrical, and biohazard health risks.

Always prioritize personal safety; if you suspect an issue poses a threat to your health, safety, or property integrity, isolate your water supply immediately if safe to do so, and consult a qualified professional. MSV Plumbing Services and its technicians accept no liability for actions taken by individuals attempting DIY diagnostics or repairs based on the content of this article. Always verify that your attending tradesperson holds a current, valid QBCC license before work commences.