The moment a pipe bursts, turn off the water at the internal stopcock — the main valve that controls the cold water supply into your home. Stopping the flow at source limits the damage far more than mopping or catching water. Once the supply is off, open the cold taps to drain the system, then deal with the leak and any standing water before arranging a permanent repair.
This guide explains the immediate steps in order, where to find the controls that stop the water, and why pipes fail in the first place. The aim is to help you act calmly and quickly, then understand what a proper fix involves once the emergency has passed.
First moves the moment a pipe bursts
Speed matters more than precision. A burst pipe under mains pressure can release a great deal of water in a short time, so the priority is to cut the flow rather than work out exactly where the leak is.
Work through these steps in order:
- Turn off the internal stopcock. This is usually a small wheel or lever valve that stops cold water entering the house. Turn it clockwise to close it.
- Open the cold taps. Run the kitchen and bathroom cold taps to drain water out of the pipework and relieve pressure. This reduces how much can escape from the burst.
- Switch off the heating. If the leak is on a hot pipe or near a boiler, turn the heating off so it doesn't keep firing with a falling water level. With most modern systems, switch off at the programmer or thermostat.
- Cut the electricity to affected areas. If water is anywhere near sockets, light fittings, or the consumer unit (fuse box), turn off the relevant circuits at the mains. Never touch electrical fittings that are wet.
- Drain the hot water. Once the cold taps run dry, open the hot taps too to clear the rest of the system.
With the water stopped, you can turn to water damage limitation — the practical work of protecting the building and your belongings. Catch drips in buckets, lift rugs and move furniture away from wet areas, and soak up standing water with towels or a wet-and-dry vacuum. Lifting carpets early helps the floor beneath dry out and reduces the risk of mould.
If you cannot stop the water, or if it is coming through ceilings or near electrics, treat it as an emergency. A leak overhead can bring down plasterboard, so keep clear of bulging ceilings. Many households also note the time and take a few photographs of the damage, which can be useful when making an insurance claim later.
Where to find and use the stopcock
The moment a pipe bursts, turn off the water at the internal stopcock — the main valve that controls the cold water supply into your home.
The internal stopcock is the single most useful thing to locate before an emergency happens. In most UK homes it sits under the kitchen sink, but it can also be found in a downstairs toilet, a utility room, a cupboard near the front door, or under the stairs. It is a brass valve on the pipe that brings cold water in from the street.
To close it, turn the handle clockwise — "righty-tighty". Older stopcocks can be stiff if they have not been used for years, and some seize up completely. It is worth checking yours works now, while there is no pressure, by turning it off and on again gently. If it will not budge or weeps when moved, a plumber can free or replace it before it is ever needed in anger.
There is usually a second valve outside, the external stopcock, often under a small metal cover near the boundary of the property. This belongs to the water company and controls the supply to the whole property; it may need a special key to operate. If the internal stopcock fails, the external one is the back-up.
Beyond the main stopcock, many homes have isolation valves — small in-line valves on individual pipes feeding a single appliance, tap, or toilet. They usually have a slotted screw that you turn a quarter-turn with a flat-head screwdriver, so the slot sits across the pipe to close it. If a burst is at one fixture, isolating just that fitting lets you keep water on elsewhere in the house. Knowing which valve feeds what saves time when something goes wrong.
Why pipes burst, from frost to corrosion
Pipes fail for several reasons, and understanding the cause helps explain why a temporary stop-gap is rarely a lasting fix.
Frozen pipes are the classic winter culprit. Water expands as it freezes, and the pressure has to go somewhere. A frozen section often splits or pushes a joint apart, but the leak only appears once the ice thaws and water flows again. Pipes in unheated lofts, garages, and against external walls are most exposed. Lagging — foam insulation sleeves — and keeping the heating ticking over in cold spells both reduce the risk.
Corrosion is the slow alternative. Older steel and iron pipes rust from the inside, and copper can develop pinhole leaks over decades, especially where water chemistry or stray electrical currents accelerate the wear. These bursts tend to start as a damp patch or a faint hiss rather than a sudden flood.
Other common causes include:
- High water pressure stressing joints and fittings over time.
- Ground movement or vibration loosening connections, sometimes from nearby building work.
- Accidental damage, such as a nail or screw driven through a hidden pipe during DIY.
- Worn fittings, where old compression joints or push-fit connectors give way.
Stopping the water and patching a split is only the first stage. A temporary repair — tape, a clamp, or a putty bandage — buys time but is not a substitute for proper work. A permanent burst pipe repair usually means cutting out the damaged section and fitting a new length of pipe with sound joints, then testing the system under pressure before closing everything back up.
A plumber will also look at why the pipe failed, not just where. If frost was the cause, they may recommend insulation or rerouting an exposed run. If corrosion is widespread, replacing a longer section, or eventually repiping, can prevent the next leak. Where pressure is high, a pressure-reducing valve might be suggested. The repair that lasts is the one that addresses the underlying weakness, which is why the calm minutes after stopping the water matter so much.
Last reviewed: June 2026