Frozen water pipes in winter: prevention and what to do if it happens

Why pipes freeze in the first place

Water expands by roughly a tenth as it turns to ice, and a pipe that is full and closed at both ends has nowhere to let that pressure go. It is not usually the cold alone that splits a pipe, but the ice plug forming and pushing outward against copper, PEX or old steel.

The pipes at risk are the ones running somewhere the heating does not reach: a crawl space under a summer cottage, an unheated garage, the space behind kitchen cabinets on an outside wall, or a loft where a header tank sits above the insulation. In a 1930s wooden house in Kalamaja or Nõmme, this is often the original plumbing run along an outside wall with no thought given to it when the house was built. In a Soviet-era panel flat, the risk is lower because pipes usually run through heated space, but a cottage or a private house is a different matter entirely.

Protecting pipes before the cold arrives

The straightforward fix is foam pipe insulation, sold by the metre in most builders' merchants, sized to the pipe diameter. It slides over the pipe and is taped or glued at the joins; on an exposed run this takes an afternoon and costs little compared with the alternative.

Anywhere the insulation cannot easily reach — a pipe passing through an outside wall, or a tap at a summer cottage — a heat trace cable wrapped along the pipe under the insulation is worth the outlay. It switches on automatically below a set temperature and draws very little power for what it protects.

Before the first hard frost, walk the whole run once: crawl space, loft, garage, any external wall boxing. If you are not sure what you are looking at or whether an old pipe run is properly protected, a plumber can check it in an hour; our plumbing work starts from 45 € per hour for exactly this kind of inspection and fix.

What to do during a sharp cold snap

When the forecast drops well below freezing for several days running, the main defence for an at-risk pipe is to keep a trickle of water moving through it. Moving water freezes far more slowly than still water, so opening the tap fed by the vulnerable pipe to a thin, steady stream is often enough to get through the worst of it.

At a closed-up summer cottage this is not usually practical, so the safer approach before leaving for the season is to drain the system properly: shut the stopcock, open all taps, and if there is a boiler or water heater, drain that too. An empty pipe cannot freeze and split.

In an occupied house, keep the heating on low rather than off in any room with exposed pipework, and open cupboard doors under sinks on outside walls so the room's warmth reaches the pipe behind them.

• Let taps on at-risk pipes run a thin, steady trickle during a hard freeze
• Keep the heating on, even at a low setting, in rooms with exposed pipes
• Open cabinet doors under sinks on outside walls
• Drain an unoccupied cottage's system fully before leaving for winter
• Check exposed pipe insulation is still in place after autumn storms

Recognising that a pipe has actually frozen

The usual sign is a tap that gives a weak trickle or nothing at all, while taps elsewhere in the house work normally. That points to a blockage somewhere in that particular run rather than a wider supply problem.

Follow the pipe by hand from the tap backwards toward where it enters the heated part of the house. A frozen section often feels noticeably colder than the rest of the pipe, and in some cases you will see frost or condensation on the outside of it. Bulging or a slight split in the surface means the pipe has already been damaged by the ice and needs a plumber before you do anything else with it.

Thawing a frozen pipe without making it worse

Open the tap on the frozen run first, so that as the ice melts the water has somewhere to go and steam pressure cannot build up behind it. Then warm the pipe gradually, starting from the tap end and working back toward the blockage — warming the middle of a frozen section first can trap pressure between two plugs of ice.

A hairdryer on a low setting, a hot water bottle laid against the pipe, or towels soaked in hot water and wrapped around it all work well and are simple to control. Electric heat trace cable, if you already have it fitted, does the job on its own.

Never use a naked flame, a blowtorch or any tool that heats one spot to a high temperature fast. Sudden, uneven heat is exactly what cracks a pipe that the ice has already weakened, and it turns a frozen pipe into a burst one.

If the pipe has already burst

Shut off the stopcock immediately — usually near the water meter or where the supply enters the house — and open the nearest taps to drain the remaining pressure out of the pipe. This matters more than anything else in the first few minutes.

Switch off electricity to any area where water is running near sockets or a consumer unit, and call a plumber; this is not a job to leave until a convenient moment, since a split pipe under pressure can flood a room in a short time. Once the burst section is cut out and replaced, it is worth having the whole run checked, and if a radiator was affected by the flood or needs moving as part of the repair, that is a separate job we quote from 85 € per radiator.