Burst pipe in your London home? The first 10 minutes that matter most

A burst pipe ruins a kitchen ceiling in about an hour. It ruins floorboards in three. The first ten minutes you spend after spotting one are the difference between a £400 repair and a £15,000 insurance claim. Here is what to do, in order, before you do anything else.

1. Find your stopcock and turn off the water

Right now, if you have not done this already today, find your internal stopcock. It is the only valve that will stop water entering your house. In most London homes it is:

• Under the kitchen sink, towards the back
• In a downstairs cupboard near the front door
• In the cellar (Victorian houses often)
• Inside the meter box outside the front door (purpose-built flats sometimes)

It is usually a brass valve with a small wheel or lever. Turn it clockwise to close. Some old stopcocks are stiff. If yours has not been used in years, it may not turn at all, in which case the external stopcock at the boundary is your backup (water company tool needed, but a screwdriver wrapped in cloth often works in an emergency).

Two minutes spent finding this when there is no emergency saves twenty minutes of panic when there is one. If you have not done this in your current home, do it now.

2. Turn off the boiler and the immersion heater

Once the cold mains is off, you also need to stop heating water. Switch the boiler off at the front panel. If you have an immersion heater (a separate hot water cylinder, usually in an airing cupboard), switch the immersion off at the wall.

Why: hot water keeps coming out of the burst pipe until the cylinder or boiler is empty, and a heater running with no water flow can damage itself.

3. Open every tap

This sounds counter-intuitive but it is right. Open every cold and hot tap in the house. Flush the toilets. The faster you drain the system, the less water there is to escape from the burst.

Open them in this order:

1. Lowest cold tap (often a downstairs tap or outside tap)
2. Lowest hot tap
3. All other taps

Within a few minutes the flow will reduce to a dribble. The pipe will keep dripping for hours as the system fully drains, but the volume drops fast.

4. Contain the water that has already escaped

Towels first, buckets second. Move anything valuable away from the leak area. Lift rugs. If water is dripping through a ceiling, put a bucket under the worst spot and (if you have access) drill a small hole in the lowest point of the bulge to let it drain in a controlled way. A ceiling holding ten litres of water will collapse without warning. A small drilled hole prevents that.

If water is on a wood floor, lift the boards if you can do so safely. Wood floors trap water against the joists below and rot the structure.

5. Document everything

For your insurance claim:

• Photograph or video the source of the leak before you do any cleanup
• Photograph all damaged items
• Write down the time you discovered it and the time you stopped the water
• Keep all damaged materials until the loss adjuster has seen them
• If you call a plumber, keep the invoice

Most home insurance covers escape of water and the resulting damage, but pays out faster when the documentation is good. Photos taken before cleanup are worth thousands.

6. Call a plumber

Now you have time to think. The pipe is not getting worse and the damage is contained. Call someone who can come the same day to make a permanent repair. Most "emergency plumbers" advertised online are call centres that subcontract to whoever is available, often at three times the price of a local independent. If you have 30 minutes to research, you will almost certainly find a better deal than the first Google result.

Send a WhatsApp with:

• Your postcode
• A photo of the burst (if accessible)
• What you have already done (water off, taps open, etc.)

A real plumber can usually quote a fixed price from those photos and tell you when they can attend.

What plumbers actually do for a burst pipe

For a simple copper pipe burst, the repair is:

1. Locate and expose the burst (sometimes the hardest part if it is under floors)
2. Cut out the damaged section
3. Solder or push-fit a new section in place
4. Pressure-test to confirm
5. Refill the system and check for further leaks

Total time on site: 1 to 3 hours for an accessible burst. Cost in 2026 London: typically £250 to £600 depending on access.

For a hidden burst (under floorboards, in a wall, in a ceiling void), add diagnostics time and floor-board lifting. Typically £400 to £900.

The two most common causes

In my experience the top causes of burst pipes in London homes are:

1. Frozen pipes (winter)

A pipe full of water that freezes will expand and split. The pipe does not leak while it is frozen, only when it thaws. Most "burst pipe" calls in January and February are actually thaw failures from a freeze that happened a day or two earlier.

Pipes most at risk:

• Loft pipes (poorly insulated lofts)
• Pipes against external walls
• Outside taps that were not drained for winter
• Pipes in unheated outhouses or garages

Prevention: lag exposed pipes with foam insulation (£10 a length from any DIY store). Drain external taps in November.

2. Old fittings failing

Compression fittings made before about 1995 sometimes fail without warning. The olive (the small brass ring inside the joint) corrodes or the nut works loose. You see this most in 1960s to 1980s extensions where copper pipework has been undisturbed for decades.

If you spot any green or white corrosion around a copper joint, it is on its way to leaking. Worth getting it replaced as a planned job before it bursts on a Sunday night.

When you cannot find the stopcock

A useful backup if you cannot turn off your water:

1. External stopcock. Outside the property boundary, usually on the pavement. There is a small metal cover (sometimes labelled "W" for water). Inside is a vertical valve that needs a long water-key tool. In an emergency, a screwdriver wrapped in a thick cloth and used with a long lever often works.

2. Push-fit isolators on individual fixtures. Many modern installations have isolators on the pipework feeding each tap, toilet, washing machine. Look for a slotted screw on the side of a copper pipe near the fixture. A coin in the slot, turned 90 degrees, isolates that fixture.

3. The water company. Thames Water emergency line is 0800 316 9800. They can shut off at the street if needed, usually within an hour.

After the repair

Once the pipe is fixed and water is back on, walk through the house and look for:

• Any drips from joints that were disturbed during the repair
• Any reduced pressure at any tap
• Any boiler fault codes (boilers sometimes lock out after a system drain)
• Any soft spots in floors or sagging in ceilings

Anything off, mention it to whoever did the repair while they are still on site or the same week.

Get the stopcock test done now

If you read this and you have not located your stopcock, do it now and turn it once. If it does not turn freely, it needs replacing before you ever need it in an emergency. A new stopcock is a 30-minute job, around £80 to £150 in London. Worth ten times that the day a pipe bursts at 11pm.

If you want me to do it as a planned visit, send a WhatsApp. I cover every London borough and a stopcock check or replacement is a quick, cheap insurance policy against a much worse day.