Leaks and burst pipes

If a pipe is leaking, close the stop tap to stop the flow, then work out where the water is coming from and whose pipe it is before you pay anyone. A plumber for leaks can usually fix a pipe inside your home in a single visit, but a leak on the pipe running from the street to your door raises a separate question about who is responsible. This guide covers how to spot a hidden leak, how to tell a burst from a weep, what to do about frozen pipes, how insurance and the water company fit in, and how to choose someone to repair it.

Find your stop tap before you need it

Every home should have an internal stop tap, and most people discover where it is in the middle of a flood. It is normally on the cold mains pipe where it enters the house: under the kitchen sink, in a cupboard, under the stairs or in a cellar. Turn it off and on once a year so it does not seize. If it will not turn or does not close fully, that is worth a plumber's visit by itself.

Out on the street, the water company has its own stop tap box. That is the company's equipment and not yours to operate.

Burst, weep or drip: reading the signs

Different leaks behave differently, and the pattern gives clues about the cause.

Heating leaks are a separate problem from drinking water leaks. If a radiator valve is dripping or your boiler pressure keeps falling, the water is in a sealed circuit, and the fix is different. For drips from a radiator valve or falling boiler pressure, start with radiators and heating instead.

If the water is gushing and you cannot isolate it, this is an urgent job, and our guide to the emergency plumber explains what to do while you wait.

Check the meter for a hidden leak

If you have a water meter, it can reveal a leak you cannot see. Discover Water suggests turning off every water-using appliance, waiting 30 minutes for the cisterns to fill, and then checking whether the meter reading is still going up. If it is, water is escaping somewhere between the meter and a tap.

Toilets are the usual culprit. Water UK says a leaking toilet flush can waste between 215 and 400 litres a day, and its research puts average household use at 323 litres a day. In other words, one faulty flush can use as much as a whole household normally does in a day, and it makes almost no noise. A few drops of food dye in the cistern, left for ten minutes without flushing, will show up in the bowl if the valve is letting water through.

Whose pipe is it?

This is the question that decides who pays. The simple version, from Discover Water, is that owners are responsible for the maintenance of the supply pipe running from the street to their property, and that if it leaks, the water company may be able to repair it for them. It is worth asking, because some companies run repair schemes of their own.

The other pieces are as follows.

• The water main under the road and the communication pipe that connects it up to your boundary or outside stop tap are generally the water company's responsibility. Report a leak on the street to them as soon as possible.
• Your supply pipe is yours, from the boundary into the house. It may be under a front garden, drive or path.
• Shared supply pipes serving more than one home can be a joint responsibility, so ask your neighbours and your water company.
• Pipes inside the house are yours, unless you rent. Tenants should report leaks to their landlord promptly, and landlords are generally the ones who arrange the repair.

Boundaries differ by company, so check your water company's own definition. A plumber can usually trace which side of the boundary a leak is on; a leak detection specialist can find buried pipes with listening equipment.

For the scale of the problem, Discover Water reports that water companies lost an average of 2,967 million litres a day to leakage over the three years to March 2025, across 352,119 km of mains. That is the companies' side. Your own pipes are your responsibility.

Frozen pipes: thawing and prevention

Water expands as it freezes and the pipe may split as the ice melts, so a frozen pipe becomes a leak when it thaws. If a tap runs dry in cold weather:

1. Close the stop tap before you start so there is no flow when the ice clears.
2. Open the affected tap so the water can run as it melts.
3. Thaw gently with a hot water bottle or a warm cloth, working from the tap end back along the pipe. Never use a naked flame or a blowtorch.
4. When water flows, check every joint for leaks before turning the supply back on fully.

To prevent it, insulate pipes in lofts, garages and outhouses, fix leaking taps that can freeze with a drip, and keep the heating on low while you are away. Know that the water company's mains can freeze too: Discover Water notes that freezing cold can cause the ground to contract around mains, leading to bursting.

What to tell your insurer

Many home policies cover escape of water, with an excess and conditions. Check yours before the repair, not after. In general:

• Phone the insurer as soon as the leak is under control.
• Photograph the damage and the pipe before anything is moved.
• Ask whether they have an approved repairer, and whether you must use them.
• Keep any parts a plumber removes if the insurer might want to inspect them.
• Ask the plumber to put the cause and the work done in writing.

Do not assume a slow leak is covered: some policies exclude damage from a leak that went on over a long time. Read the wording.

Choosing a plumber for leaks

For water pipework, look for a plumber on the WaterSafe register, which Discover Water recommends if you find a leak in your pipes. For anything that involves gas pipes or a boiler, the engineer must be Gas Safe registered instead; see how to check a plumber is Gas Safe or WaterSafe registered.

Good questions to ask:

1. How will you find the source, and will it involve lifting floorboards or cutting walls?
2. Is the price fixed or hourly, and does it include making good?
3. What guarantee do you give on the repair?
4. Do you replace the section or patch it?

A patch can be enough for a new fault in sound pipe. If the pipe is old, corroded or has failed in several places, replacing the whole run often works out cheaper than repeated call-outs.

The rules that cover repairs

Water fittings in the UK are governed by the Water Supply (Water Fittings) Regulations 1999. Regulation 4 says fittings must be of an appropriate quality and standard and installed, repaired or altered in a workmanlike manner. Regulation 5 requires notice to the water company before certain listed work begins, and the company has ten working days to respond before consent is treated as granted. Notice applies only to the operations listed in the regulation, so ask your plumber whether your job is one of them. WaterSafe says its approved contractors can issue Certificates of Compliance. For related building rules, see do you need building regulations approval for plumbing and heating.

What affects the cost of a leak repair

We do not quote prices, as every leak is different. What moves a bill is:

• How hard the leak is to find, and whether detection equipment is needed.
• How much has to be opened up, and who makes good the plaster, flooring or tiling.
• Pipe material and length of the section replaced.
• Whether the water has to be drained down, including the heating system.
• Time of day, and the call-out terms.

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