Water expands as it freezes, and that pressure splits pipes. The crack often shows only when it thaws - and then it floods. A little prep before winter prevents the whole mess.
A burst from a frozen pipe is one of the most common winter insurance claims. Prevention costs a few pounds; the cleanup costs thousands.
Before the Freeze
Foam pipe insulation from any DIY shop is cheap. Prioritise lofts, garages and outside walls.
In a cold snap, set heating to a low constant temperature rather than fully off, even when away.
Lag any loft or garage water tank and fit an insulated cover on outside taps - cheap, and they freeze first.
If a pipe does burst, you'll want to stop the water in seconds, not search for the valve mid-flood.
Which Pipes Freeze First
- Loft and roof-space pipes
- Above the insulation and away from heat - the most common place to freeze.
- Garage and outbuilding pipes
- Unheated and often forgotten. Lag them and drain outside taps.
- Outside taps and supply pipes
- Garden taps and any pipe run along an external wall freeze early - lag them and fit a tap cover.
Going Away in Winter?
- Leave the heating on a low frost setting while you're gone
- Ask a neighbour to check in during a cold snap
- For longer trips, consider draining the system down - a plumber can advise
- Know where your stopcock is and that it actually turns
If a Pipe Freezes
- Turn off the water at the stopcock straight away
- Thaw it gently - a hairdryer or warm towels, working from the tap end back
- Never use a naked flame or blowtorch on a pipe
- Watch closely as it thaws; if you find a split, leave the water off and call a plumber
If It Has Already Burst
Close the stopcock and open the cold taps to drain the system fast. Not sure where it is? See our guide to turning off your water.
Move furniture and electricals, and contain the water with buckets and towels.
Photograph the damage for insurance, then get a professional to make the repair.
How Cold Does It Have to Get?
Pipes start to freeze once the temperature around them drops below zero for a sustained spell - and it's the pipes in cold, unheated spaces that go first, even when your rooms feel fine. A run of sub-zero nights is the classic trigger, which is why a cold snap brings a wave of burst-pipe call-outs a few days later, as the ice thaws and the splits let go.
- Loft, garage and outside-wall pipes are most at risk
- A few sub-zero nights in a row is the danger window
- The burst often shows on the thaw, not during the freeze
- Leaving heating on a low setting keeps the whole system above freezing
Protecting an Empty Property
Homes left empty over winter - holiday breaks, second homes, properties between tenants - are where the worst frozen-pipe floods happen, because no one is there to catch it. A little planning avoids coming back to a ceiling on the floor.
- Leave the heating on a low frost-protection setting
- Ask a neighbour to look in during any cold snap
- For a long absence, have a plumber drain the system down
- Make sure someone knows where the stopcock is and can reach it
Frozen Pipes and Your Insurance
Burst-pipe damage from freezing is usually covered by buildings insurance, but many policies expect you to take reasonable precautions - keeping the heating on in cold weather, or draining the system if the home is left empty for a stretch. Skipping that can give an insurer grounds to reduce a payout, so it's worth knowing your policy's wording.
Prevention is far cheaper than the clean-up, but if a pipe does go, our emergency plumber cost guide shows what a repair runs to. Flooding now? Stop the water, then get an emergency plumber on the way.