Cracked Pipe? How to Stop the Leak and Get It Fixed

What to do the moment you find a cracked water pipe, the temporary fixes that hold until a plumber arrives, why pipes crack in cold weather, and how a cracked section is repaired properly.

If you've found a cracked water pipe, the first thing to do is turn the water off at the stopcock, then open the cold taps to drain what's left in the pipes. That stops the damage getting worse. A repair tape, clamp or epoxy putty can hold a small crack for a few hours, but a cracked pipe can't be trusted once it has split, so the damaged section needs cutting out and replacing. This guide covers what to do in the first ten minutes, which temporary fixes actually work, and what a proper repair involves.

What to do first

Turn off the water at the stopcock

It's usually under the kitchen sink, but in London flats it can be in a hallway cupboard, a bathroom or a communal riser. Turn it clockwise. If it won't move, see our guide on a stopcock that won't turn.

Drain the pipes

Open the cold taps, starting with the lowest, and flush the toilets. This empties the water sitting in the pipework so less escapes from the crack.

Deal with hot water and heating

If the crack is on a hot water or heating pipe, turn off the boiler or immersion heater. Don't run hot taps dry if you have a hot water cylinder, because the heater can be damaged if it runs empty.

Keep water away from electrics

If water is near sockets, a light fitting or the consumer unit, or is coming through a ceiling, switch off the electricity at the consumer unit if it's safe to reach. Don't touch anything electrical while standing in water.

Contain and record

Put down towels and a bucket, move belongings away and take photos of the pipe and any damage for your insurer or landlord.

If water is pouring out and you can't stop it, follow our burst pipe guide and call a plumber straight away.

Finding the crack

An exposed pipe with a visible split is easy. A hairline crack, or one hidden inside a wall, under floorboards or behind a kitchen unit, takes more work. Signs to look for:

Water dripping from a joint or along the underside of a pipe. Dry the pipe with a cloth and watch where the water reappears.
Damp patches, stains or bubbling paint on ceilings and walls.
The sound of running water when every tap and appliance is off.
A water meter that keeps turning when no one is using water.
On a heating pipe, boiler pressure that drops every few days and needs topping up.

If you can't find it, a plumber or a leak detection visit can trace it without lifting more floor than necessary.

Temporary fixes that work

These can hold a small crack or pinhole long enough to get water back on for a while. They're not a substitute for a repair, and none of them should be relied on for a pipe inside a wall or ceiling where a failure would go unnoticed.

Self-amalgamating repair tape. A rubbery tape that fuses to itself when stretched. Dry the pipe, then wrap it tightly, overlapping each turn by half, starting a few centimetres either side of the crack. Good for small cracks on straight pipe.
Pipe repair clamp. A metal clamp with a rubber pad that bolts round the pipe over the crack. It must match the pipe diameter, which is usually 15mm or 22mm on domestic copper. The most reliable of the temporary options.
Epoxy putty. A two-part putty you knead together and press over the crack. It sets hard and works on awkward shapes such as bends and joints, but the pipe must be dry and clean.

Don't use heat. Never use a blowtorch or naked flame on a pipe, especially one that may still be frozen. It can damage the pipe, start a fire in a loft or wall void, and on older homes may disturb materials that shouldn't be disturbed.

With a temporary fix in place, turn the water back on slowly and watch the repair for a few minutes. If it weeps, turn the water off again.

Why pipes crack

Freezing. The most common cause in winter. See the next section.
Age and corrosion. Old copper can thin from the inside, and older galvanised steel rusts through. Pinholes and cracks tend to appear in the same stretch of pipe over time.
Movement and knocks. Pipes that aren't clipped properly move every time a tap is turned off. Over years that flexing can crack a pipe or loosen a joint, particularly where it passes through a wall or floor.
Pressure surges. Loud banging when taps close, known as water hammer, puts repeated stress on pipes and joints. Our water hammer guide explains the fixes.
Accidental damage. A nail or screw through a floorboard or wall is a common cause after building work or when fitting shelves.
Plastic pipe issues. Plastic pipe can split if it's kinked, crushed or wasn't pushed fully into its fitting.

Cracked pipes in cold weather

Water expands as it freezes. When a pipe freezes solid, the pressure has nowhere to go, and it can split a copper pipe or force a joint apart. The frustrating part is that the crack often stays hidden while the pipe is still frozen, then starts leaking once the ice thaws.

If a pipe is frozen, turn off the water at the stopcock before you start thawing it, so a crack doesn't flood the house when the ice melts. Thaw it slowly with a hot water bottle, warm cloths or a hairdryer on a low setting, working from the tap end back. Our guide to frozen pipes covers this step by step, and our advice on preventing frozen pipes is worth reading now, before the first cold snap. Lagging exposed pipes in lofts, garages and outside walls is the cheapest protection there is.

How a cracked pipe is repaired

The standard repair is to cut out the damaged length and join in new pipe. On copper that means compression fittings, soldered joints or push-fit connectors, depending on where the pipe is and how much room there is to work. A short section of exposed pipe is usually a quick job. It takes longer when the crack is inside a wall, under a floor or in a spot that needs boards or units lifting first.

A good plumber will also look at why it cracked. If the pipe is badly corroded, replacing a longer run may make more sense than patching one spot. If it cracked because of frost, the pipe needs lagging or rerouting. If it's an old lead supply pipe, it should be replaced rather than repaired. See our pipe replacement and lead pipe replacement pages.

Who pays? Pipes inside your home, and usually the supply pipe from your boundary to the house, are the owner's responsibility. The water company generally looks after the pipes on its side of the boundary. If you rent, report the leak to your landlord straight away. Our guide on whether home insurance covers plumbing explains what's usually covered.

When to call a plumber

Call a plumber if you can't stop the water, if the crack is on a heating pipe or near the boiler, if it's inside a wall or ceiling, or if the pipe is old and you suspect it will crack again. The same goes if a temporary fix is holding but you need the water back on properly. Our burst and cracked pipe repair service covers exposed and hidden pipework, and for general pipe leaks see our leaking pipe guide.

Our labour is £95 an hour, the £60 call-out is waived when the job runs over 2 hours, and we confirm the price before any work starts.

Pipe cracked or leaking?

Tell us where the pipe is and whether you've been able to turn the water off. We'll confirm the price before starting.

📞 Call 020 7870 3200

Or see our pipe repairs and pricing.

Frequently Asked Questions

Can you fix a cracked pipe without replacing it?

Only temporarily. Repair tape, a pipe repair clamp or epoxy putty can stop or slow a small leak for a few hours or days, but the pipe is still weakened. The lasting repair is to cut out the cracked section and join in a new length of pipe.

Is a cracked pipe an emergency?

If water is escaping and you can't stop it at the stopcock, or it's near electrics or coming through a ceiling, treat it as urgent. If you've turned the water off and the leak has stopped, you have time to arrange a repair, though you'll be without water on that part of the system until it's fixed.

Why do pipes crack in winter?

Water expands as it freezes. In a pipe that's frozen solid, the pressure has nowhere to go and can split copper or plastic pipe or push a joint apart. Pipes in lofts, garages, outside walls and unheated rooms are most at risk.

How do I know if a pipe is cracked behind a wall or under the floor?

Look for damp patches or stains, bubbling paint, a musty smell, the sound of running water when everything is off, or a water meter that keeps moving when no water is being used. On a heating pipe, the boiler pressure dropping over a few days is a common sign.

Who is responsible for a cracked water pipe?

Pipes inside your home, and in most cases the supply pipe running from your property boundary to the house, are the owner's responsibility. The water company is generally responsible for the pipes on its side of the boundary. If you rent, tell your landlord straight away.

Cracked Pipe: How to Stop the Leak and Get It Fixed

Key Takeaways