Installing a frost-proof outdoor tap can be done two ways: you fit an ordinary wall tap with a drain valve at the lowest point indoors (so you can empty the pipe before winter), or you fit a frost-proof wall tap that only shuts off deep behind the wall and drains itself after every use. In both cases you tee off your existing cold water pipe, put a check valve or air gap device on the branch (required for your drinking water), and run the wall passage with a slight fall to the outside. Reckon on around 40 to 80 euro in materials if you do it yourself, or roughly 150 to 350 euro if you call in a plumber. Below we walk you through both approaches step by step.
Why an outdoor tap freezes and cracks in winter
Water has an annoying habit: when it freezes, it expands. By as much as about 9 percent in volume. That sounds small, but in a closed copper or plastic pipe there is no room to take up that expansion.
The result is enormous pressure from the inside. At the weakest spot the pipe splits, a joint pops loose or the internals of the tap burst.
The nasty part is that you often only spot the damage in spring. As soon as it thaws, the water runs through the crack into your wall or crawl space. Then you have not only a broken tap but possibly water damage too.
It almost always goes wrong in the same places: in the bit of pipe that runs through the cold outside wall, and in the tap itself. That is exactly where standing water sits with nowhere to go.
The two ways to make it frost-proof
There are two proven approaches. Which one suits you depends on how much fuss you want each autumn and whether you have a suitable lowest point indoors.
Approach A: ordinary tap with an indoor drain valve
You fit a normal wall tap outside. Indoors, at the lowest point of the branch, you fit a stop valve with a drain nipple (also called a drain valve or air gap device).
Before winter you close the stop valve, open the outside tap and the drain nipple, and let all the water run out of that bit of pipe. Empty means freeze-proof.
Upside: cheap and buildable with simple materials. Downside: you have to remember it yourself every autumn. Forget it once and you still run a risk.
Approach B: frost-proof wall tap
A frost-proof wall tap (also called a wall-through tap) has a long spindle. The shut-off point is not at the tap outside but deep behind the wall, on the warm inner side.
Turn the tap off and it shuts off inside. The water still standing in the long outlet drains itself to the outside via a slight fall. So no standing water is left in the cold part.
Upside: in winter you have to do (almost) nothing. Downside: the tap itself is dearer, and it only works well if it is fitted with the right fall and you disconnect the hose after use.
| Tap + drain valve | Frost-proof wall tap | |
|---|---|---|
| Purchase price of tap | Low (copper from about 20 euro) | Higher |
| Work in autumn | Drain every time | Almost none |
| Risk if forgotten | Present | Small |
| Fitting | A bit simpler | Fall is crucial |
Important: even a frost-proof tap only drains if nothing is attached. If the hose, sprinkler or watering computer stays connected, it holds the water back and the tap can still freeze.
Required: backflow protection for your drinking water
Do not skip this. An outdoor tap must not let contaminated water flow back into your drinking water pipe. Think of hose water, pond or pool water, or fertiliser drawn in through a sprinkler.
The rules for this are set out in EN 1717 and, in the UK, in the Water Supply (Water Fittings) Regulations. In short: an outside tap needs at least a check valve (single check valve), and for use with a garden hose a combination of a double check valve or a check valve and an air gap device.
Many frost-proof wall taps have this protection built in. If you choose an ordinary tap, buy a tap with a built-in double check valve, or fit a check valve directly after the branch point on your pipe.
Ideally check a check valve yearly. According to the water fittings guidance, backflow protection should be inspected periodically, because dirt can make the valve stick.
What you need
Materials:
- A frost-proof wall tap, or an ordinary wall tap with a hose union
- A wall plate or backplate elbow to fix the tap to
- A check valve or double check valve tap (if it is not in the tap)
- A stop valve with a drain nipple for the lowest point indoors (for approach A)
- Copper pipe or plastic pipe, usually 15 mm for enough pressure
- A branch fitting (tee) plus the connections that suit your method: solder fittings, compression fittings or press fittings
- Pipe insulation for the section in the outside wall
- Expanding foam or sealant with a wall sleeve to seal the hole
- Fixings (wall plugs, screws, pipe clips)
Tools:
- A pipe cutter
- A drill with a long masonry bit for the wall passage
- Spanners or slip-joint pliers
- A blowtorch (for soldering) or a press tool (for press fittings)
- A spirit level
- A bucket and cloths
Soldering is the cheapest and most durable joint, but it takes practice and a dry pipe. Compression fittings are the easiest for the DIYer: no flame needed. Press fittings are quick and reliable, but the press tool is a costly buy or hire.
Step by step: installing the outdoor tap
1. Turn off the water. Find your main stopcock at the meter and close it. Then open a low-level tap to release the pressure and empty the pipe as much as possible.
2. Decide the position. Choose a sensible spot for the tap outside, ideally within reach and not too high. Indoors, find the lowest point on the branch pipe, because that is where the drain valve goes in approach A.
3. Drill the wall passage. Drill through the wall where the pipe goes outside. Drill at a slight angle so the hole sits a little lower on the outside than on the inside. That fall makes water drain outward instead of standing in the wall.
4. Tee off the existing pipe. Cut the cold water pipe at the chosen spot and fit a tee with solder, compression or press fittings. Work cleanly and make sure the joint is fully watertight.
5. Fit the backflow protection. Fit the check valve directly after the branch point, or use a double check valve tap further along. Do not skip this step.
6. Fit the drain valve (for approach A). Fit the stop valve with drain nipple at the lowest point indoors. This is how you shut off and drain the outside section in winter.
7. Run the pipe outside. Run the pipe with a slight fall through the wall passage to the outside. Insulate the section that passes through the cold wall.
8. Fix the tap. Screw the tap onto the wall plate or backplate elbow and fix it firmly into the wall. Make sure the tap sits level and does not wobble.
9. Seal the wall hole. Fill the space around the passage with expanding foam or sealant so no cold and damp get inside. Finish it off neatly and weatherproof on the outside.
10. Test. Turn the water back on and check every joint for leaks, from the tee to the tap. If you see a drip, nip up the connection a little. Let the tap run well to flush out any dirt.
Getting your outdoor tap ready for winter
If you chose approach A, you drain it every autumn. The order matters:
- Disconnect the garden hose. A connected hose holds water back and can block the pipe.
- Close the indoor stop valve. Now no new water can get through.
- Open the outside tap. Leave it fully open.
- Open the drain nipple. Catch the water in a bucket. The pipe between the stop valve and the outside tap now drains.
- Leave the outside tap open. That way any leftover water that does freeze can expand without splitting the pipe. Close the drain nipple again.
Do this before the first night frost. In practice that means being alert from November, because a single hard freezing night can be enough.
If you have a frost-proof wall tap, it is simpler: disconnect the hose and turn the tap off. It then drains itself. In principle you need do no more, provided the fall is right.
Realistic costs
Doing it yourself. A good wall tap soon costs 40 to 50 euro; a simple copper tap starts at about 20 euro. Add pipe, fittings, a check valve, a drain valve and insulation. For the complete materials package you are often looking at 40 to 80 euro, depending on the distance and the quality of the tap.
Calling in a plumber. Having a professional fit an outside tap costs on average around 150 to 350 euro. Some firms work with fixed rates of around 300 to 400 euro including materials, usually up to a set distance from the mains. If your water pipe is far from the wanted spot, or extra pipe has to be run, the price goes up.
The biggest cost driver is the distance between your existing pipe and the tap’s position. The further, the more pipe and work.
Common mistakes
- Leaving the garden hose on. The most common mistake. Then neither an ordinary nor a frost-proof tap can drain.
- No fall. Without a slight slope to the outside, water stays in the cold part. Then even a frost-proof tap does not work.
- Forgetting to drain. With approach A, one forgotten autumn is enough for a split pipe.
- No check valve or air gap device. Besides being required for your drinking water, you risk contaminating your own tap water.
- Drain valve not at the lowest point. If it sits too high, water stays below it and still freezes.
- Leaving the outside tap closed after draining. Leave it open instead, so leftover water has room to expand.
- Not sealing the wall passage. An open hole draws cold inside and actually raises the freezing risk.
Frequently asked questions
Do I still need to shut off a frost-proof outdoor tap in winter?
In principle you do not need to drain a frost-proof wall tap separately, because it shuts off behind the wall and drains itself. But you must always disconnect the garden hose and turn the tap off, otherwise it cannot drain and will freeze and crack anyway.
When should I get my outdoor tap ready for winter?
Before the first frosty spell, so be alert from November. A single hard night frost can be enough to split a pipe. Waiting until it is really cold is too late.
Is a check valve really required on an outdoor tap?
Yes. Under EN 1717 and the water fittings regulations, an outside tap must have backflow protection so that contaminated water cannot flow into your drinking water. For use with a garden hose, a double check valve, or a combination of a check valve and an air gap device, is standard. Many frost-proof taps have this built in.
Can I connect an outdoor tap myself or does a plumber have to do it?
With a bit of skill you can do it yourself. If you work with compression fittings, you do not need a blowtorch. If you are unsure about teeing off your water pipe or about the drinking water protection, have a professional do it. A leak inside the wall costs more than the labour you saved.
Why does the pipe have to lie on a fall?
So that the water drains outward after use and no standing water is left in the cold part of the pipe. It is exactly that standing water in the outside wall that freezes and causes most of the damage.
What do I do with my garden hose in winter?
Disconnect it, let it drain and store it somewhere frost-free, such as the shed or garage. A hose full of water freezes and can split, and as long as it is on the tap it blocks your pipe from draining.
Get started
An outdoor tap that gets through winter without trouble is not a matter of luck but of clever fitting: a fall to the outside, a drain valve at the lowest point or a genuine frost-proof tap, and a check valve for your drinking water. Do it well and you will enjoy it for years without surprises in spring.
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