Burst water main or burst pipe: how to tell and who to call

When water suddenly appears where it should not, the first question is whose pipe it is. The answer decides who you call, who pays and how quickly anything happens. In London the line is clear on paper, even if it is hard to see in the street.

Thames Water’s pipe responsibility page sets it out. Thames Water owns the water mains under the roads and the short communication pipe that links the main to your property. From your property boundary into your home, the supply pipe is yours, as is every pipe, tap and appliance inside.

How to tell which one you have

What you see	Most likely cause	Who to call
Water bubbling up through the road or pavement	Burst water main or communication pipe	Thames Water
Many homes in the street lose water at once	Burst main or works	Thames Water
Wet patch or soft ground in your front garden or path	Your supply pipe	A plumber
Water meter turning with every tap off	Leak on your side, often the supply pipe	A plumber
Water inside the home, from a pipe or fitting	Your internal pipework	A plumber
Only your house has no water	Your pipework, valve or an airlock	Check stop tap, then a plumber or Thames Water

If you are not sure, ask the neighbours. A burst main affects the whole street. A burst supply pipe usually affects only the home or homes it serves.

Burst mains in Lewisham’s hilly streets

Lewisham has a lot of houses compared with central London. In the 2021 Census, 26.2% of Lewisham households lived in terraced houses and 16.0% in detached or semi detached houses. That means more people with their own front gardens and their own supply pipes under them, and more chance that a wet patch on the path is yours rather than the water company’s.

Lewisham is also hilly, from Forest Hill to Hilly Fields above Brockley. After a burst main, Thames Water says pressure can take several hours to come back, and customers at the top of a hill are likely to take longer than those at the bottom. The water may splutter out of the taps at first and should clear if you run them for a couple of minutes.

Reporting a burst main

If you see water coming up through the road or pavement, report it to Thames Water online, or call its customer care team on 0800 316 9800. Note the street, the nearest house number and how much water is coming out. If the water is flowing towards homes or basements, say so.

Do not try to dig, turn valves in the road or move barriers. Mains are under pressure and can undermine the road surface.

If it turns out to be your supply pipe

A burst supply pipe usually shows as a wet patch or a sunken area in the front garden, water seeping out between paving slabs on your path, or a sudden drop in pressure. If you are on a meter, a meter that keeps spinning with every tap off is a strong sign.

You can turn off the water at your inside stop tap, but that will not stop a leak on the supply pipe between the outside and inside stop taps. For that, Thames Water says you can use the outside stop valve, which is normally under a cover in the path or the road. It may need a stopcock key. If your house is old and shares a supply with neighbours, the valve may be at the end of the road, and turning it off will cut their water too.

Supply pipe repairs often mean digging up part of the path or garden. A plumber will find the leak, expose the pipe and replace the damaged section, sometimes replacing the whole run if it is old. If Thames Water has confirmed a leak on your property, you have four weeks to arrange a repair. Our guide on the Thames Water four week rule explains what that means.

Shared supply pipes in Lewisham terraces

In older terraced streets, one supply pipe sometimes serves several houses before it branches. Thames Water says that when this happens, you and your neighbours have joint responsibility for maintaining the shared part of the pipe and any costs, and it does not get involved in disputes between neighbours. If a shared pipe bursts, talk to the neighbours early and agree who will arrange the repair.

After the water comes back

Once a burst main has been fixed, a few things are normal.

• Low pressure for a while. Give it a few hours, especially on higher ground.
• Cloudy or milky water. Thames Water says this is usually tiny air bubbles and should clear within two to three hours.
• Brown or orange water. Deposits disturbed by the burst. If neighbours have it too, tell Thames Water. If only you do, it may be your own pipes.
• No water when neighbours have it. Possibly an airlock. Thames Water asks you to call it.

If property damage was caused by a burst main, Thames Water asks you to call 0800 316 9800 and it will pass you to its claims team.

Compensation for supply interruptions

Water companies in England follow the Guaranteed Standards Scheme set by Ofwat. Citizens Advice says compensation can be paid if standards are not met when your supply is interrupted for repairs or an emergency such as a burst pipe. Thames Water says it credits eligible household customers automatically.

When to call a plumber

Call a plumber when the leak is on your side of the boundary, when only your home is affected, or when water is escaping inside. For a burst pipe inside the home, turn off the stop tap, switch off electrics near the water, open the cold taps to drain the system and contain the water while you wait.