How to thaw a frozen pipe without splitting it, and how to stop the next cold snap catching your home out — for Coleraine and the north coast.
Open the affected tap slightly, then thaw the pipe with gentle heat only — a hairdryer on low, warm towels or a heated room — working from the tap end back towards the frozen section. Never use a blowtorch or any naked flame. And if the pipe has already split, stop: keep the water off at the stopcock and call a plumber instead.
The first warning is usually a tap: it slows to a trickle or stops altogether in freezing weather, while the rest of the house carries on as normal. Sharp overnight frosts are a regular feature of winter around Coleraine, Castlerock and the north coast, and pipes freeze most often in lofts, garages and other unheated corners — including holiday lets left empty for weeks at a time. Follow the pipework that feeds the dead tap through the coldest spaces it crosses and feel for a section that's noticeably colder than the rest; sometimes there's frost on the outside of the pipe to give it away.
Slowly, and from the right end. Open the affected tap slightly so melting water has somewhere to go, then warm the pipe gently — a hairdryer on a low setting, warm towels, a hot water bottle, or simply getting some heat into the room — working from the tap end back towards the frozen section. That way the ice melts towards an open outlet instead of building pressure against a plug of ice.
Never use a blowtorch or any naked flame. Rapid, fierce heat is exactly how a frozen pipe becomes a cracked one, and an open flame around joists, insulation and old timber is a worse emergency than the one you started with.
Lagging is the dull, cheap answer that works: foam sleeves on any pipework running through the loft, the garage, or along outside walls take minutes to fit and protect the runs that freeze first. In a proper cold snap, keep the heating ticking over on a low setting rather than letting the house go stone cold overnight — and if you look after a property that stands empty for stretches over winter, as plenty do along the coast towards Portstewart and Portrush, it's worth asking a plumber about shutting the water off at the stopcock and draining the system down before the frosts arrive.
Then the job changes: you're no longer thawing a pipe, you're preventing a flood. Keep the water off at the stopcock and leave it off — the ice inside the pipe is currently the only thing holding the water back, and thawing it will simply turn a frozen pipe into a flowing one. Open the cold taps to drain what's left in the system, move anything electrical clear of the area, and call a plumber to repair the split before the water goes back on. If you're not sure whether it's split or just frozen, treat it as split until you can see otherwise.
Open the affected tap slightly, then work from the tap end back towards the frozen section with gentle heat only — a hairdryer on low, warm towels, a hot water bottle, or simply heating the room. Take your time: thawing too fast can crack the pipe. Never use a blowtorch or any naked flame.
A tap slowing to a trickle or stopping altogether in freezing weather is the usual giveaway. Follow the pipework that feeds it through the coldest spaces it crosses — the loft, the garage, an outside wall — and feel for a section that's noticeably colder than the rest, sometimes with frost on the outside.
Lag any pipework that runs through lofts, garages or along outside walls — foam sleeves are cheap and fit in minutes. In a cold snap, keep the heating ticking over on low rather than letting the house go stone cold, and make sure you know where the stopcock is before you ever need it in a hurry.
Keep the water off at the stopcock and leave it off — thawing a split pipe simply turns a frozen pipe into a flowing one. Open the cold taps to drain what's left in the system, keep electrics clear of any wet areas, and call a plumber to repair the split before the water goes back on.
In freezing weather, yes — a low background setting keeps the water in the pipes above freezing and costs far less than putting right the damage from a burst. If a property will stand empty for a longer stretch over winter, it's worth asking a plumber about turning the water off at the stopcock and draining the system down instead.
Back to the Coleraine emergency plumber home page, or jump to another guide:
Stopcock first: the three steps that limit water damage fast.
Read the guide →Pressure basics, no heat or hot water, and what to do about a gas smell.
Read the guide →What never to pour away, and when a blockage is a main-drain problem.
Read the guide →An honest look at call-out fees, hourly rates and out-of-hours pricing.
Read the guide →Pressure, thermostat, tripped switch or diverter valve — checks first.
Read the guide →Damp patches, dropping pressure, and the stopcock test that narrows it down.
Read the guide →The main page: what to do right now and the areas covered.
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