Do I need to turn my outside tap off in winter?

Yes, and turning it off is only half the job. Close the isolating valve indoors, then open the outside tap and leave it open through the winter so the trapped water can escape. The check valve at the tap stops that section draining back into the house on its own.

Why does my outside tap have a check valve?

To stop contaminated water being drawn back into the mains — from a hose left in a pond or a bucket, for example. WaterSafe state the water fittings regulations specify outside taps should always have a double check valve, and Schedule 2 of the Water Supply (Water Fittings) Regulations 1999 requires an adequate backflow prevention device in every water system.

There is no isolating valve for my outside tap. What should I do?

Either insulate the tap and its exposed pipe as well as you can and accept the residual risk, or have a plumber fit an isolating valve on the internal pipe. It is a short job, and it also means a future problem with the tap does not require shutting the whole property down.

My outside tap froze but nothing is leaking. Is it fine?

Not necessarily. A split usually happens in the copper behind the tap, inside the wall, and stays plugged by its own ice until the thaw. Look for damp on the internal face of that wall and at the skirting in the room behind before assuming it survived, and check again after the first warm day.

Are frost-proof outside taps worth fitting?

They shift the shut-off point back inside the wall so the exposed section drains itself every time the tap is closed, which removes the problem rather than managing it. Worth specifying if a tap is being replaced anyway, rather than a reason to replace a working one.

Outside Taps and Garden Pipework Before Winter

Disconnect the hose, close the indoor isolating valve that feeds the tap, then open the outside tap and leave it open all winter. The check valve required at every outside tap stops that short run draining back into the house, so unless you open the tap the water stays in the pipe and freezes in the coldest part of the wall.

Leak Fix LondonLast updated 19 September 2026

A Leak Fix London engineer working on pipework in a London home

Five minutes, before the first frost

Disconnect the hose and drain it. WaterSafe's advice for the tap itself is to turn the hosepipe off at the tap and, ideally, fully disconnect it and store it clean and dry when it is not in use. A hose left connected holds a column of water against the tap and freezes solid.
Find the isolating valve inside. On most installations there is a small valve on the pipe feeding the outside tap, usually just inside the wall the tap passes through — under a kitchen sink, in a utility cupboard, or on the pipe in a garage. It may be a lever, or a slot-headed screw valve you turn with a flat screwdriver until the slot lies across the pipe.
Close it.
Open the outside tap fully and let the trapped water run out.
Leave the outside tap open all winter. This is the step people skip, and it is the one that matters.

Then insulate what is left: the tap body and the exposed pipe. WaterSafe's winter advice is to insulate outside taps and pipes in unheated areas with foam insulation — outdoors that has to be the waterproof, weatherproof kind, because ordinary indoor foam soaks and then freezes around the pipe rather than protecting it.

Why the outside tap is the most predictable burst in London

An outside tap sits at the end of a short run of pipe that passes through an external wall. The tap itself is in the open air, the pipe is in the coldest part of the masonry, and — unlike the rest of your plumbing — nothing warm ever flows through it between April and October.

The part most people do not know is the reason that short run does not empty itself. Every outside tap should have a double check valve on it. WaterSafe state that the Water Supply (Water Fittings) Regulations, which exist to keep drinking water safe, specify outside taps should always have a double check valve to prevent backflow; homes built since 1999 usually have an inline valve in the supply pipe to the tap, and older properties usually have one built into the tap itself. The underlying requirement in Schedule 2 of the Water Supply (Water Fittings) Regulations 1999 is that every water system shall contain an adequate device or devices for preventing backflow of fluid.

The valve is doing an important job: it stops contaminated water — from a hose left lying in a pond, a water butt, a bucket of weedkiller — being siphoned back into the mains. But it is a one-way valve, which means that when you close the isolating valve indoors, the water between that valve and the tap has nowhere to go. It cannot drain backwards, and unless you open the tap it will not drain forwards either. It sits there, in the coldest pipe in the house, all winter.

That is the whole mechanism. Isolating without opening the tap achieves nothing at all.

If there is no isolating valve indoors

Plenty of outside taps, particularly ones added by a previous owner, are teed straight off a kitchen supply with no isolation. In that case you cannot drain the run without turning the whole house off, and your options are: insulate the tap and its exposed pipe as well as you can and accept the risk, fit an insulated tap cover, or have a plumber fit an isolating valve on the internal pipe. The last one is a short job and it is worth doing, because it also means a split outside tap does not mean shutting the whole property down.

Frost-proof or self-draining outside taps exist as well. They put the shut-off point back inside the wall so the exposed section empties every time you close them. They are a sensible choice when a tap is being replaced anyway.

Everything else in the garden

Irrigation timers and automatic watering systems. The timer body holds water, the solenoid holds water, and both split. Remove the timer, drain it and bring it in.
Pressure washers. Water left in the pump housing freezes and cracks the casing. Run it dry, or use the manufacturer's antifreeze procedure.
Water butt pumps and pond pumps. Lift, drain and store, or keep running where the manufacturer allows it.
Standpipes serving a garage, a shed, a garden studio or a basement flat's rear yard. Same rule: isolate inside, open the outlet, leave it open.
Outside taps on a communal wall in a block. If it is not on your demise, it is the managing agent's job. Tell them in October rather than discovering in January that nobody did it.

Where the split actually shows up

A frozen outside tap rarely fails at the tap. The tap itself is brass and usually survives; what splits is the copper immediately behind it, inside the wall, where the ice plug forms and the water trapped between the ice and the closed tap has nowhere to expand. Which means that when the thaw comes, the water does not run out of the tap where you can see it. It runs into the cavity, down the inside of the external wall, and appears as a damp patch on the internal face of that wall, in the room behind, or at the skirting — often several metres from the tap and sometimes a floor below.

That is the version of this job we get called to. The homeowner reports a wet wall in a back room and does not connect it to a garden tap they have not used since September. Finding a leak inside a wall covers how it is actually located; a wet patch on a wall covers the diagnosis from the symptom end.

One maintenance item worth knowing

Check valves do not last forever. WaterSafe note that the British Standard BS EN 806-5 states check valves should be replaced every ten years. A failed double check valve is not a freezing risk — it is a water quality one — but if you are having a plumber fit an isolating valve or replace an old tap, it is the moment to deal with the check valve too, and to use a compliant fitting approved by a body such as BSI, KIWA, NSF or WRAS.

When not to call us

Draining an outside tap is a five-minute job and nobody should be paid to do it. Fitting an isolating valve or replacing an outside tap is an hour of a general plumber's time, and a leak specialist is the wrong trade for it.

Call us when the tap has already done its damage and the water is somewhere you cannot see. A split behind an external wall soaks brickwork and insulation before it shows on plaster, and cutting into the wall to look for it is how a small repair becomes a large one. We pressure-test to confirm the loss is real, then trace the run with thermal imaging, moisture mapping and, on a drained section, tracer gas, so the wall is opened at one point. Where the opening leaves a hole in plaster or render, our own team makes it good — that is pipework repair and reinstatement in the same visit where the access allows. Our rate is £150 per hour, agreed before we attend. If we are looking for a hidden leak and do not find it, you do not pay for the time we spent looking.

If the tap is still dripping from the spout when it is closed, the washer is worn, and how to change a tap washer covers the fix before you isolate it for the winter.

Frequently asked

Do I need to turn my outside tap off in winter?: Yes, and turning it off is only half the job. Close the isolating valve indoors, then open the outside tap and leave it open through the winter so the trapped water can escape. The check valve at the tap stops that section draining back into the house on its own.
Why does my outside tap have a check valve?: To stop contaminated water being drawn back into the mains — from a hose left in a pond or a bucket, for example. WaterSafe state the water fittings regulations specify outside taps should always have a double check valve, and Schedule 2 of the Water Supply (Water Fittings) Regulations 1999 requires an adequate backflow prevention device in every water system.
There is no isolating valve for my outside tap. What should I do?: Either insulate the tap and its exposed pipe as well as you can and accept the residual risk, or have a plumber fit an isolating valve on the internal pipe. It is a short job, and it also means a future problem with the tap does not require shutting the whole property down.
My outside tap froze but nothing is leaking. Is it fine?: Not necessarily. A split usually happens in the copper behind the tap, inside the wall, and stays plugged by its own ice until the thaw. Look for damp on the internal face of that wall and at the skirting in the room behind before assuming it survived, and check again after the first warm day.
Are frost-proof outside taps worth fitting?: They shift the shut-off point back inside the wall so the exposed section drains itself every time the tap is closed, which removes the problem rather than managing it. Worth specifying if a tap is being replaced anyway, rather than a reason to replace a working one.

Sources

No find, no fee · £150 per hour. The rate is fixed before we attend and does not rise for a difficult property, an awkward access or an evening visit. The total depends on how long the job takes; the rate cannot change.