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Water mains leak detection

Mains supply pipe leak repair

A leak in your water mains supply pipe can be difficult to diagnose and have expensive consequences for your water bill unless fixed quickly.

Water travels through these pipes at high pressure and can cause substantial damage when a hole is created by corrosion, the weather or simple old age.

Discover how we approach water mains leak detection below.

Your mains supply pipe is your responsibility

Many people believe that it’s the job of their water company to fix a faulty mains pipe, but sadly this is unlikely to be the case for the majority of UK properties.

Your external stop valve controls the supply of water to your home from the street and is different to the internal stopcock usually found beneath your kitchen sink.

You are responsible for any leak or issue that occurs between the external valve and your property, whether beneath your garden or the building itself.

Water mains leak detection is the process of finding, fixing and sometimes replacing, the broken underground pipes which transport water from the public network to your home.

Use the contents box to navigate to the part of the page you need or simply call us for free now on 0800 037 7078 to discuss your specific situation with our team, without obligation.

Need extra help? Read our helpful guide: Should I repair or replace my water mains pipe?

The telltale signs of a burst mains water leak

Mains water leaks can be hard to notice due to the fact they are mostly located underground, however there are a number of above-ground clues that could signal a problem.

  • Is your water meter spinning when your stopcock is off? Your water meter will typically be installed on or near the external stop valve of your property. You can quickly determine if your water leak is between the external valve and your internal stopcock by turning off the stopcock and seeing if your meter continues to turn. We recommend leaving the stopcock off for at least an hour or two and monitoring any difference in the meter value. See more on this process below.
  • Have you been surprised by usually high water bills? While it’s common for water usage to fluctuate throughout the year, if you’ve received a bill from your water company that doesn’t seem to reflect your actual usage, it may signal a hidden leak requiring immediate attention.
  • Are you experiencing low water pressure? A leak in your mains pipe can cause the pressure of the supply to your home to drop, resulting in slower running taps and showers. A noticeable change in water pressure with no wider issue reported by your supplier should be investigated. Water travels through mains supply pipes at high pressure and a leak can quickly release large volumes of water in a short period of time.
  • Have you noticed unusual levels of mould, condensation or smell of damp? The escape of water from your mains supply pipe running beneath your home can cause significant areas of damp or mould to develop in your home. We recommend that you urgently investigate the cause of dampness and condensation that you can’t otherwise account for.
  • Does your garden show signs of saturation or subsidence? If you live in a house, the journey from the external stop valve to your internal stopcock will likely travel beneath your front garden from the street. A leak in this area can often be spotted by an unusually wet patch of grass or evidence of subsidence in the ground.
Mains water leak

Locating a leak on mains supply pipework

As a specialist leak detection company, we are well equipped to find even the deepest and most difficult leaks in your mains water pipe using the latest non-destructive methods.

Our leak detection technologies include everything from acoustic equipment and moisture meters, to tracer gas, thermal imaging and endoscopic cameras.

But before we can offer solutions, we need you to spot the symptoms. If you’re reading this, you’ve probably already got a hunch that you have a water leak, but there’s a fairly simple way you can confirm it yourself.

How to confirm a leak using your water meter and internal stopcock

The below test can be carried out without any plumbing experience and used to verify the presence of a leak in your main water supply pipe. By completing the following steps, you will be able to see if you’re using water despite not using water at all.

Step One: Isolate and turn off your home’s internal stop valve (stopcock). Learn how to find this in our guide: What’s the difference between outside and inside stop valves?

Step Two: Open your kitchen tap to confirm that your home’s internal water supply has stopped.

Step Three: Check your water meter – usually found on the ground outside your property (see image below) – for movement. If you notice the dial or the plus (+) sign moving, you probably have a leak.

External stopcock and water meter

I’ve noticed the dial moving. What next?

If you’ve completed the steps above and the dial of your water meter is still spinning, we recommend that the first thing you do is tell your water company about your suspected leak.

Our guide – When to tell your water company about a leak – includes a full breakdown of this process as well as the contact details of major water suppliers, including Affinity Water, Thames Water, SES Water and South East Water.

Already spoken to your water company?

If you’ve spoken to your water company or already know that your leak is your responsibility to fix, we can help.

We’re experts at tracing and repairing water leaks in all areas of your home and garden.

Call us free now on 0800 037 7078 to arrange a free visual inspection of your leak by one of our expert technicians.

All calls to us are without obligation. We can provide you with a full fixed quotation before any work is conducted and you won’t pay us a penny before the work is completed.

Why do I have a high water bill?

As living costs rise nationwide, it’s no surprise to see bills shooting up at alarming rates.

Knowing whether your high water bill is the result of wider economic shifts, or a leak in your mains pipe, can save you a lot of time and money.

Most water companies estimate your six-month water usage and collect payments monthly or quarterly through direct debit.

This billing process means it’s not always immediately clear when and by how much your water usage has spiked, but a cost increase usually means more water was used.

High water bill mains leak

Why have I used more water?

A high water bill isn’t always the fault of an undetected water leak in your home. Below are some of the most common reasons:

New water-using appliances: Your bill may have increased due to new or heavier use of water-consuming appliances.

Larger household size: More people or animals in the home often leads to higher water usage.

Outdated fixtures: Inefficient plumbing or leaky fixtures contribute to water waste.

Fast-spinning water meter: A busy water meter can indicate a potential leak, requiring prompt attention to prevent further water loss (see section below).

Detecting leaks in mains water supply pipes

We offer a fixed price trace and access service following the completion of a free visual inspection of your property. This visual inspection does not involve the use of any specialist detection equipment, but allows us to accurately gauge and price the work required.

Upon instruction to complete trace and access works, we will use one or a variety of the methods to locate your mains supply pipe before providing you with a further option for its repair.

These methods include the use of tracer gas, thermal imaging and endoscopic cameras.

1. Call 0800 037 7078

Our trace and access services are approved by all UK insurance companies. Call us for free today to discuss your situation and book in a free visual inspection by one of our expert technicians.

2. We’ll inspect your leak for free

Upon booking, we will carry out a free visual inspection of your reported water leak to provide you with a structured price for the trace, access and repair. The visual inspection will not find your leak by itself.

3. Get a fixed price to find your leak

We know how frustrating it can be when a price changes throughout a job. The price we quote you for the work will be the price you pay. Plus, we’ll provide you with a detailed report to submit to your insurance company.

Why does my underground water main pipe leak?

It’s natural to wonder why a pipe buried beneath your home may suddenly start to leak when it’s worked perfectly fine for many years.

Unfortunately, the breakdown of a pipe over time is mostly inevitable and unavoidable. The best thing to do when it happens is to act swiftly to arrange a repair and ensure that you have appropriate insurance in place to cover the costs.

And remember that sometimes, the most cost-effective long term solution is the full replacement of your mains water pipe.

Here’s three of the most common that reasons water main supply pipes fail:

Water main pipe repair

The pipe is old and prone to corrosion

Many new-build properties in the UK benefit from modern pipework constructed from materials including ductile iron and PVC. Older pipes are a lot more susceptible to corrosion and a lot less resilient to changing temperatures, which can cause fractures and cracks over time.

High water pressure and ruptured the pipe

Regional water suppliers invest a lot of money in pressure management strategies to help maintain a consistent flow of water to your home. Changing water pressure through your mains pipe can lead to extreme surges causing the pipe to either leak or burst.

If you’re concerned about the water pressure supply to your home, we recommend contacting your water supply company directly before a problem has time to develop.

The pipe has been damaged by excavation work

Construction work at your property can lead to your mains supply pipe being damaged by machinery or equipment. The pipe usually runs around six feet below ground and hitting it can trigger a leak that may require repair or replacement completely.

Water mains leak detection FAQs

Dealing with insurance companies can be a frustrating experience, especially when you’re claiming for cover you’ve probably never needed before. We’ve included some of the most common questions regarding water mains leaks below.

Remember, if you still have a question, you can call us now on 0800 037 7078.

What should I do if I can’t find my external stop valve?

Locating your external stop valve is essential if you’re planning to self-diagnose the cause of your water leak. However, if you’re struggling to find it, your water supplier should be able to point you in the right direction. If you’re not sure who your supplier is, this handy tool from Water UK can help.

What if I live in a flat or a building containing multiple properties?

Blocks of flats or apartments may have either a single of multiple stop valves to control water supply to the building. Meters inside communal properties are specific to each home and you will only be charged for your own use, not that of your neighbours!

What does it mean when there’s a leak in my mains supply pipe?

A leak in your mains supply pipe signifies a disruption in the system that transports water from the public supply to your home. Mains pipe leaks can be challenging to identify and may result in higher water bills and potential property damage if left unattended.

Who is in charge of rectifying a leak in the mains supply pipe?

Contrary to common belief, for most properties in the UK, it is the property owner who is responsible for rectifying issues or leaks occurring between the external stop valve and their property and not the water company.

What might happen if a mains water leak isn’t addressed promptly?

Ignoring a mains water leak can lead to a range of consequences from inflated water bills to extensive damage to your property due to dampness, mould and even subsidence.

We repair mains water leaks throughout the UK

Water leaks can happen at any time and can go unnoticed for weeks, months or even years. Miracle Leak Detection offers an unrivalled five-star water mains leak detection service across the UK.

Visit the links below to explore our most visited counties. including Hertfordshire, Surrey and London.


Get your water leak found and fixed fast in all areas of Hertfordshire, from Bishops Stortford and St Albans, to Watford and Ware.

Water Mains Leak Detection in Hertfordshire


We cover all areas in Surrey and south London, including Guildford, Epsom, Haslemere and more. View all of our Surrey locations below.

Water Mains Leak Detection in Surrey


Need us to find your leak in London? We work throughout greater London and the suburbs, as well as deep within the heart of the city itself.

Water Mains Leak Detection in London


The historic county of Cambridgeshire is home to thousands of old and new properties liable to mains leaks. Don’t be caught out when trouble strikes.

Water Mains Leak Detection in Cambridgeshire


The county of Essex stretches from rural Sawbridgeworth to the sea of Southend. We find underground leaks from countryside to coastline.

Water Mains Leak Detection in Essex


Nestled between our other areas of service, Bedfordshire is perfectly placed for our team to quickly and efficiently repair your mains water leak.

Water Mains Leak Detection in Bedfordshire

Testimonials from our mains leak customers

We’re proud of the mains leak detection service that we offer our customers, with five star reviews on Google, Trustpilot and Checkatrade. Read a selection of our reviews below.

Underground mains leak detectionWatford WD3, Sept. 2023

I can highly recommend Barrie and his company. Visited our property to give a quote and a thorough run down of the work required ensuring that I understood the detail. After booking them in they turned up on time at very short notice and completed the work quickly and professionally - keeping us informed of their progress throughout. They even went above and beyond to improve the plumbing that was not part of the original quote to save digging up the driveway again. They did a great job - highly recommended.

Flooded garden mains leakHertford SG13, Sept. 2023

Water had been leaking for some time causing lots of damage to a field and entrance which made it impossible to use. Tractor had managed to get stuck! Called Miracle Leak Detection having seen their van locally and they were available that day due to a job cancellation. They fully explained the detection process and sent a cost breakdown before the work started so no surprises. Found the leak to a stopcock we didn't even know existed. Repairs were completed and reinstatement made as best as they could considering it was a quagmire there. Really efficient and professional. Many thanks guys.

Internal water mains pipe leakTrustpilot, Aug. 2023

We had a leak which was extremely difficult to access but Barrie was not going to be beaten. Barrie talked us through what he thought needed to be done and gave us quote which he said would not change. He worked so hard and in a very confined space. It wasn't at all straight forward and took far longer than expected but he was true to his word the price did not change! We don't think many people would have been prepared to do the job he did and we feel very fortunate that we chose Miracle Leak Detection. Would have given many more stars if it were possible.