Underground water leak detection along the buried supply pipe

Where does United Utilities' pipe end and your supply pipe begin?

United Utilities' pipe ends at the boundary of your property: the communication pipe from the main in the road to the boundary, and the external stop tap in the footpath, are United Utilities', and the supply pipe from the boundary into your home is yours, with every pipe inside.

The drawing walks the pipe from the street to the house. The main runs under the road, and a short communication pipe leaves it for the property boundary, with the external stop tap in the footpath on the way; United Utilities looks after all three. From the boundary the supply pipe crosses the drive or garden to the internal stop tap indoors, and that length, the stop tap and every pipe beyond it are the owner's.

• United Utilities says the common supply pipe that connects each branch pipe "is the collective responsibility of all connected homeowners", while each branch pipe and the pipework inside each home belong to that homeowner.
• United Utilities says: "If the pipe only supplies your home, you're usually responsible for maintaining it, even where part of the pipe is outside your property boundary."
• United Utilities says that in some cases, particularly in rural areas, an owner may be responsible for more pipework, between the part of the street where the main is laid and the property, or where the supply pipe crosses someone else's land.
• United Utilities says: "If you live in a rented property, it is your landlord's responsibility to repair the leak."
• United Utilities' meter terms say the water meter remains United Utilities' property.

Three parts of the region follow other companies' rules. Severn Trent supplies the city of Chester with water only: it took over Dee Valley Water's operations in Chester in 2018, when Dee Valley Water's customers in England moved to Severn Trent. Severn Trent's responsibility stops at the boundary of the highway where its main or communication pipe is laid; from there, Severn Trent says, the supply pipe is the owner's, even where it crosses other private or public land before it reaches the home.

Pendle Borough Council's Infrastructure Delivery Plan says United Utilities manages water supply in Pendle "with the exception of the area around Earby, which is the responsibility of Yorkshire Water", and Yorkshire Water's own supply-area checker places Earby, Barnoldswick, Kelbrook and Salterforth inside its area. In the Craven villages of the LA2 and LA6 districts, including High and Low Bentham, Ingleton, Burton in Lonsdale, Clapham and Austwick, United Utilities' checker shows it as the wastewater provider, and Craven District Council's plan says "clean water supply is provided by Yorkshire Water."

Anyone unsure of their own supplier can check it town by town on the page of which water company supplies your area, or read United Utilities' Water Supply Pipes page for its own rules in full.

What are the signs of a leak on an underground supply pipe?

The signs of a leak on an underground supply pipe are a waterlogged front garden, lush growth or damp patches on the ground, lower pressure at the taps, and, on a metered bill, a rise with no other explanation.

• Outside the home, a waterlogged front garden (WaterSafe) and lush growth or damp ground patches (Wessex Water) are listed as signs of a leak.
• Falling pressure at the taps is another sign: Aviva names lower water pressure, WaterSafe less pressure at the kitchen tap, and Wessex Water a big fall in water pressure.
• United Utilities says that when a metered bill has gone up, "It could be because you have a leak, but you may also be using a lot more water than you normally would and don't realise."

The meter test in the next section checks for a leak whether or not any of these signs has shown.

How does a water meter reveal an underground leak?

A water meter reveals an underground leak when its reading keeps rising with every appliance off and the internal stop tap closed, which United Utilities says makes a leak on the underground supply pipe likely.

United Utilities normally fits a water meter inside the home, on the supply pipe close to the stop tap, usually under the kitchen sink or in a downstairs toilet or garage; where it cannot go inside, it fits the meter outside, in a box on an outside wall or in the street close to the property boundary. United Utilities' steps, in its order, run as follows.

1. Turn off every appliance that uses water.
2. Wait 30 minutes for tanks and cisterns to fill.
3. Take a meter reading, including the red digits.
4. Wait 3 to 6 hours without using any water, then take a second reading.
5. Turn off the internal stop tap, wait 30 minutes and take a third reading.
6. Wait another 2 hours and read the meter again.

If the reading has gone up with the stop tap closed, United Utilities says "it's likely you have a leak on your underground supply pipe". If it has stayed still, the leak is more likely inside, and pipe leak detection takes over from there. These steps come from United Utilities' Perform a leak test page, which also asks whether the meter is inside or outside the home. United Utilities' leakage code of practice gives other timings for the same test, asking you not to use any water for at least one hour, and longer, ideally overnight, if you can.

Without a meter, Wessex Water's listening test applies. With taps and water-using appliances off, listen at the internal stop tap, where a hissing or knocking noise is the clue, then close the tap and listen again: a noise that carries on puts the leak most likely outside the property, and a noise that stops puts it most likely inside.

How is a leak under a drive or lawn pinpointed?

A leak under a drive or lawn is pinpointed by pressure testing the supply pipe to confirm it is losing water, then listening at the surface with a ground microphone, or filling the drained pipe with a hydrogen and nitrogen tracer gas and finding where it comes up through the surface.

Sewerin's method moves the listening stick from point to point along the pipe and its fittings: the two loudest points bracket the leak's approximate position, and a ground microphone then narrows it to one spot.

Hydrogen is used because its molecules are the smallest and lightest of all, which lets it out through the finest opening; Sewerin says it rises quickly through concrete, tarmac, block paving and grass. Sewerin and INFICON both say the 5% hydrogen blend, which INFICON calls forming gas, is not flammable, not toxic and not corrosive.

Red Rose Leak Detection uses these readings to place the leak before a floorboard or a flagstone comes up. The limit of each method sits beside it below.

Home insurance with trace and access cover may pay for finding a hidden leak, and the policy wording decides whether a supply pipe leak is included.

Can a United Utilities bill be reduced after a supply pipe leak?

A United Utilities bill can be reduced after a supply pipe leak through United Utilities' leak allowance, which metered customers can claim for water lost through a leak on internal or external pipework once the leak has been repaired.

United Utilities says: "Metered customers are able to claim the cost of the water lost during a leak on your internal or external pipework." Its conditions, in its own terms, are these.

• The allowance covers the first claim at the current property.
• It covers one internal leak and one external leak at that property.
• United Utilities' claim form says the leak must already be repaired before a claim is made, or the customer will not be eligible. The repair can be the owner's or United Utilities' own.
• A meter reading is taken after the repair, and a second one 14 days later.
• The claim is made within 12 months of the repair.
• United Utilities does not grant an allowance where the extra use is not due to a leak, where the customer knew about the leak but did not act promptly to repair it, or where the leak was caused by negligence.

United Utilities says that if another leak occurs at the same property, a further allowance may be possible against sewerage charges when the water running to waste does not enter the sewer network. The leak has to be dealt with promptly, and the full terms are on United Utilities' leak allowance page.

Severn Trent gives a leak allowance once only per customer per property, and none for leaks on pipework or fittings inside the home, for leaks caused by negligence or by a third party, or for a supply that has had an allowance before. Its terms are on Severn Trent's Your water supply page. Yorkshire Water says a leak allowance can be claimed once, for a leak that was not caused by negligence and that has been repaired or that the customer has asked Yorkshire Water to look into. Its terms are on Yorkshire Water's Supply pipe leaks page.

Will United Utilities help with a leaking supply pipe?

United Utilities may help: a homeowner registered for its Priority Services scheme, or receiving one of the benefits it names, "may be eligible for a free leak repair" on the supply pipe, though the scheme cannot repair a supply pipe that runs under the house, a conservatory or another permanent structure.

Who may be eligible

United Utilities says a homeowner "may be eligible for a free leak repair" on the supply pipe if registered for its Priority Services scheme or receiving one or more of Universal Credit, income-based Employment and Support Allowance, Income Support, income-based Jobseeker's Allowance, Housing Benefit or Pension Credit.

What it covers

United Utilities' free repair scheme is for domestic properties only; it cannot repair a supply pipe that runs under the house, a conservatory or another permanent structure, and it provides temporary reinstatement only, leaving permanent reinstatement to the owner.

How long it aims to take

United Utilities says: "We aim to investigate and repair leaks on a supply pipe within ten days."

Leaks found at a new meter

United Utilities says that if it finds a leak on a supply pipe while fitting an external water meter, and the leak can be repaired "without any extra digging", it repairs it free of charge.

Changes to the terms

United Utilities says it may change or withdraw the terms of its supply pipe leakage policies at any time.

A leak left unrepaired

United Utilities' leak repair booklet says that if a leak is not repaired within 30 days of being discovered, it starts the Defective Water Fittings enforcement process under the Water Industry Act 1991.

Lead and shared supply pipes

Under its Lead and Common Supply Pipe Scheme, United Utilities offers eligible owners on a lead single or common supply a free 25mm connection of a replacement supply pipe from the boundary to the main; the owner replaces the pipework inside the boundary up to the first cold water tap, and must apply and be accepted before any work is done. United Utilities' lead scheme is open where the property is "not a new build and it's not too far from a water main" and the owner has an active billing account with United Utilities; it aims to process an application within 10 working days and to complete its work within 6 weeks, and says the replacement "will reduce the likelihood of household leaks".

United Utilities explains each scheme on its Leaking supply pipe page and its Lead and Common Supply Pipe Scheme page.

Severn Trent says it checks the service pipe for leaks when it installs a meter and can repair a leak it finds there under its free repair scheme, subject to that scheme's terms, and that leaks on customers' own pipes go to its Customer Leakage Support team. Yorkshire Water says a free supply pipe repair may be available to customers on one of its support schemes.

Which leaks should be reported to United Utilities instead?

Leaks on the water main, on the communication pipe between the main and your boundary, or at the external stop tap in the footpath should be reported to United Utilities on its Report a problem page.

• Across most of the North West: United Utilities' Report a problem page for a leak in the street, and its Leaking supply pipe page for a leak on your own supply pipe.
• In Chester, leaks on Severn Trent's network are reported through its Check my area page, where its report-a-leak address leads.
• Around Earby and in the Bentham and Ingleton villages, Yorkshire Water takes leak reports through its Report a leak page and says online reports are looked at during its working hours.
• In a rented home: the tenant reports a supply pipe leak to the landlord, whose job United Utilities says the repair is.

A leak that is on none of these pipes is on the heating or the pipes indoors. Where the boiler gauge keeps falling, the search moves to central heating leak detection, and the four investigations are set out together on the page for leak detection across the North West.