How to Prevent Frozen Pipes During Cold Winter Months

When the temperature drops below freezing, the water in your pipes is at risk of freezing and expanding. That expansion can crack pipes or force joints apart, leading to a burst when the ice thaws and water starts flowing again. A burst pipe can release hundreds of litres of water into your home, damaging ceilings, floors, electrics and belongings. The good news is that most frozen pipe incidents are preventable with a few simple, low-cost steps. Here is how to protect your home this winter.

Understanding why pipes freeze and burst

Water expands as it turns to ice, increasing in volume by around 9%. If that expansion happens inside a sealed pipe, the pressure has nowhere to go. The pipe itself may not split at the frozen section; often the burst occurs further along, between the ice blockage and a closed tap or valve. That is why a pipe can seem fine while frozen, then leak badly as it thaws.

Pipes most at risk are those in unheated spaces:

• Lofts and roof spaces
• Garages and outbuildings
• Cellars and basements
• Under suspended floors
• Outdoor taps and pipes running along external walls
• Kitchen and bathroom sinks on outside walls

Even indoor pipes can freeze if the heating is off for a long period or if cold draughts reach them. The key is to keep them warm, insulated, or moving.

Insulate exposed pipework

Insulation is your first line of defence. It slows the transfer of heat from the pipe to the cold air, giving the water inside more time before it freezes. Focus on any pipe that runs through an unheated area.

Use foam pipe lagging, which comes in tubes slit along one side. Push it over the pipe and seal the slit with tape or the adhesive backing. For awkward corners and valves, wrap the pipe with insulating tape or use a fitted jacket. Pay special attention to bends, joints and taps, as these are common freeze points.

In the loft, lay insulation over pipes, but do not pack it tightly around them; trapped cold air is fine, but compressed insulation loses effectiveness. If pipes run under floorboards above a cold void, lift the boards if you can and lag them. For outdoor taps, fit an insulated tap cover or wrap the tap and the exposed pipe in foam or old towels, then secure with cable ties.

Remember that insulation only delays freezing; it does not add heat. If a pipe is already frozen, lagging will not thaw it. Combine insulation with the other steps below for the best protection.

Keep a slow drip running

On nights when the forecast is for freezing temperatures, let one or two taps run at a slow drip. Moving water freezes more slowly than still water, and the constant trickle relieves pressure if ice does begin to form. Choose the tap furthest from your stopcock, as this draws water through the longest section of pipe. If you have a combi boiler, a dripping hot tap can also keep warm water moving, but a cold tap is usually sufficient.

The drip should be about the width of a pencil lead, not a full stream. You can collect the water in a jug or bucket and use it for plants or cleaning, so nothing is wasted. If you have a mixer tap, use the cold side. For extra protection, open the cabinet doors under kitchen and bathroom sinks. This allows warm air from the room to circulate around the pipes, especially if the sink is on an outside wall.

Tackle draughts and protect outdoor taps

Cold air leaking into your home can freeze pipes faster than you might expect. Check for gaps around pipes where they enter the house through external walls. Seal these with expanding foam, silicone sealant or a purpose-made draught excluder. Fit draught-proofing strips to loft hatches, garage doors and any other openings near pipework.

Disconnect hosepipes from outdoor taps before the first frost. A hosepipe left connected can trap water that freezes and splits the tap or the pipe inside the wall. If you have an isolation valve for the outdoor tap, turn it off and drain the water out. Otherwise, fit an insulated cover over the tap. For external pipes that cannot be isolated, lag them thoroughly and consider adding a thermostatically controlled heat cable, which switches on only when the temperature drops near freezing.

What to do if a pipe freezes

If you turn on a tap and nothing comes out, or only a trickle, you may have a frozen pipe. Act quickly but gently. First, turn off the water supply at the stopcock and open the nearest tap to relieve pressure. Then thaw the pipe slowly, starting from the tap end and working back towards the frozen section. Use a hairdryer on a low setting, a hot water bottle wrapped in a towel, or warm (not boiling) water poured over cloths wrapped around the pipe.

Never use a blowtorch, naked flame or boiling water. Rapid heating can crack the pipe or cause steam burns. If you cannot find the frozen section or the pipe does not thaw, call a qualified plumber. If you notice a leak after thawing, keep the water off and arrange repairs before turning the supply back on.

Protect your home when you are away

If you are leaving the house empty for more than a day or two in winter, leave the heating on a low setting. A thermostat set to 12-15°C will keep the chill off without wasting energy. Open the loft hatch slightly to let warm air rise, and leave cupboard doors open under sinks.

For longer absences, consider draining the water system:

• Turn off the stopcock
• Open all taps to drain the remaining water
• Flush the toilets
• Turn off the immersion heater and boiler if you have a conventional system

Ask a neighbour or friend to check the house periodically, or install a smart leak detector that alerts you to damp conditions. A little preparation now can save you a great deal of stress, expense and mess later.