Frozen pipes and outside taps in Stevenage, Hitchin and North Herts

How do I know a pipe has frozen?

The usual sign is a tap that gives nothing, or only a trickle, on a cold morning while other taps work. A toilet cistern that will not refill is another. You may see frost on a pipe or feel that it is icy compared with the rest of the run.

Pipes most at risk are those in unheated places: lofts, garages, utility rooms built against an outside wall, pipes under suspended floors and anything outdoors.

How can I thaw a frozen pipe safely?

• Turn off the stopcock first, in case the pipe has already split
• Open the tap nearest the frozen section so melting water can escape
• Warm the pipe gently with a hot water bottle, a towel soaked in warm water or a hairdryer on a low setting, starting at the tap end and working back
• Never use a blowtorch, a heat gun or any naked flame
• Do not pour boiling water over a pipe, as the sudden heat can crack it or the fitting

Once water is flowing again, turn the stopcock back on slowly and watch the pipe for drips or spraying.

What if the pipe has already split?

Water expands as it turns to ice, and the pressure can split a pipe or push a joint apart. Often the leak only shows once the ice melts, sometimes hours later. Shut off the stopcock, catch what water you can, keep it away from electrics and keep people out of any room where the ceiling is sagging. Call 999 if anyone is in danger.

A plumber can replace the split length and check nearby joints that may have been strained.

How can I protect my pipes before winter?

• Lag pipes in the loft, garage and other cold spaces, and fit a cover on any cold water tank
• Leave the loft hatch open a little in a severe cold spell so some warm air reaches the space
• Keep the heating on at a low setting if you go away, rather than turning it off
• Fix dripping taps, since a slow drip in a cold pipe can freeze and block it
• Know where your stopcock is and check it turns before you need it

The water fittings rules expect pipes in cold places to be protected against freezing, so it is worth raising lagging when any new pipework is fitted.

What should I do with my outside tap in winter?

Many outside taps freeze because the short pipe through the wall holds water. If yours has an isolating valve on the pipe inside the house, close it in late autumn, then open the outside tap to let the water drain and leave it open. Disconnect the hose too, as water trapped in a hose fitting can freeze back into the tap.

If there is no isolating valve indoors, a plumber can fit one.

Does an outside tap need anything special?

Yes. A garden hose can be left in a pond, a bucket of weedkiller or a dirty water butt, and that water could be drawn back into the drinking water pipes. To prevent this, outside taps are expected to have backflow protection, usually a double check valve, either built into the tap or fitted on the pipe inside the house. Many older outside taps were fitted without one.

Fittings connected to the mains must meet the Water Supply (Water Fittings) Regulations 1999. If you are having a new outside tap fitted, ask the plumber how backflow and frost will be dealt with.

Is a frozen condensate pipe a plumbing job?

Not usually. If a gas boiler stops in freezing weather and shows a fault, its plastic condensate pipe outside may have frozen. Anyone opening up or repairing the boiler itself has to be a Gas Safe registered engineer. If you smell gas at any time, leave the building and phone 0800 111 999, the National Gas Emergency Service number.

What details help?

• your postcode
• which taps or fittings have stopped working
• where you think the frozen or split pipe is
• whether water has escaped, and whether you have turned it off
• for an outside tap: fixing an old one, swapping it or adding one, and on which wall