A burst pipe is a genuine emergency. Water escaping from a pressurised supply pipe can deliver hundreds of litres per hour into a wall, ceiling, or floor. The damage it causes — to plasterwork, timber, electrics, and belongings — often far exceeds the cost of the pipe repair itself. The most important thing you can do in the first minutes is not call a plumber. It is to stop the water.
Stop the Water First
Find your internal stopcock and turn it clockwise until it stops. The internal stopcock is almost always under the kitchen sink, but can also be in an airing cupboard, utility room, or under the stairs. Turning it off stops the flow from the cold water mains. Open all cold taps in the house to drain the supply pipes and reduce pressure. If the burst is on the hot water system (cylinder, heating pipes, or a hot supply pipe), turn off the boiler and immersion heater and drain from the lowest point.
"Every adult in a household should know where the internal stopcock is and be able to turn it off. In an emergency, a homeowner who can stop the water in under a minute will typically suffer far less damage than one who has to search for it while water is flowing."— Citizens Advice — Burst Pipes
Why Pipes Burst
Freezing
The most common cause in winter. When water in a pipe freezes, it expands by about 9% — enough to split copper pipe or crack plastic fittings. Pipes in unheated loft spaces, external walls, and under floors are most vulnerable. Insulating these pipes (pipe lagging costs very little) is the most effective preventive measure.
Corrosion
Older lead and iron pipes corrode from inside and outside. Pinhole leaks in copper pipe are caused by aggressive water chemistry, flux residue from poor soldering, or dezincification of brass fittings in soft-water areas.
Physical damage
Drilling into a wall, driving a screw through a floorboard, or movement in the building fabric can puncture or fracture a pipe. CCTV surveys before renovation work can locate hidden pipework.
High water pressure
Mains pressure above 3 bar puts significant stress on fittings, particularly older compression joints. A pressure-reducing valve (PRV) fitted to the incoming supply protects the whole installation — worth considering if your mains pressure is consistently high.
"Frozen pipes are the leading cause of burst pipes in domestic properties. The freeze-thaw cycle is particularly damaging: the pipe may not burst while frozen but fails as it thaws and pressure returns. A pipe that has frozen once should be inspected even if it appears undamaged."— ABI — Association of British Insurers: Escape of Water
What the Repair Involves
For a clean split in accessible copper pipe, a plumber will typically cut out the damaged section and replace it with new pipe — a job measured in minutes once the water is off. For a burst behind plasterwork, the location must be confirmed before any cutting begins; a damp meter or thermal camera can pinpoint the fault without unnecessary damage. Where galvanised or lead pipework has failed, the plumber may recommend replacing the run rather than patching, since adjacent sections are likely in similar condition.
Insurance and Escape of Water
Escape of water — which includes burst pipes — is covered by most standard buildings and contents insurance policies. Notify your insurer promptly, photograph the damage before any drying-out begins, and keep all receipts. Some insurers have their own approved contractors; others allow you to choose your own plumber. The Association of British Insurers notes that escape of water claims account for around 25% of all home insurance payouts by value.
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