Outside Taps: Installation, Regulations and Winter Care
An outside tap is a small job with a few specific requirements that are easy to miss.
An outside tap is a small job with a few specific requirements that are easy to miss. It has to be fed and isolated in a way that lets you drain it before winter, it needs backflow protection so garden water cannot be drawn back into the drinking supply, and where it is teed off matters for both flow and future maintenance. Getting those three things right is the difference between a tap that lasts years and one that splits in the first hard frost.
Where the supply comes from
The usual approach is to tee off the rising main inside the property, ideally close to the stopcock and before any softener or filtration, and take a short run through the external wall. Teeing off a long spur from a distant point works but costs flow. What matters more is that the connection point is accessible, because an isolating valve installed somewhere you cannot reach is an isolating valve nobody will ever use in October.
Backflow protection is a requirement, not an upgrade
Water Regulations require protection against backflow on outside taps, because a hose left in a water butt, a pond or a bucket of garden chemicals can otherwise siphon back into the supply. That is provided by a double check valve fitted on the supply to the tap, or by an outside tap with integral backflow protection. It is a small component that is genuinely there for a reason, and it is the part most commonly missing on DIY installations.
Making it winter-proof from the start
Fit an internal isolating valve and a drain-off so that in autumn you can close the valve, open the outside tap and drain the external section completely. Without that, water sits in the exposed pipe and tap body all winter and eventually freezes and splits it, usually somewhere inside the wall where the leak is least convenient. Sloping the external run slightly towards the tap helps it drain fully.
Getting through the wall properly
The core through the wall should be drilled with a slight fall to the outside, sleeved where appropriate, and made good and sealed both sides so water and draughts cannot track back in. On a cavity wall it matters that the sleeve does not bridge the cavity. Pipework in the cavity or against a cold external wall should be insulated, because that is exactly the location most vulnerable to freezing.
Choosing the tap and the position
Bib taps with a hose union are the standard. A lockable or removable-handle tap is worth considering on a front elevation. Position it clear of paths where a hose will trip people, high enough to get a watering can under, and where the wall behind can take the fixing properly. If a garden supply is likely to grow into an irrigation system or an outbuilding supply later, size the run for that now rather than teeing off a small pipe twice.
Maintenance that keeps it working
Drain it every autumn without fail. Replace the washer when it starts to drip rather than tightening it harder. Check the check valve is still passing correctly if flow drops noticeably. And keep the internal isolating valve exercised, because a valve that has not moved in five years is a valve that will not move on the evening you need it.
A properly installed outside tap has
- An accessible internal isolating valve
- A drain-off to empty the external section
- Double check valve backflow protection
- A wall core with a fall to the outside
- Insulated pipework in cold sections and cavities
- A secure fixing into sound masonry
- Sensible height and position for a hose and can
- Sealing and making good on both sides of the wall
Who does the work
- Gas Safe registered engineers — registration 554328
- Worcester Bosch accredited installer
- John The Plumb Ltd, company registration 10026483
Get an outside tap fitted properly
Tell us where you want it and where your stopcock is, and we will fit it with isolation, drainage and backflow protection done correctly.
Questions we get asked
Do outside taps legally need a check valve?
Yes. Water Regulations require backflow protection, typically a double check valve or a tap with integral protection, to keep garden water out of the drinking supply.
Why did my outside tap split over winter?
Water left in the external pipe and tap body froze and expanded. An internal isolating valve and drain-off used each autumn prevents it.
Can an outside tap reduce pressure indoors?
Only while it is running, and only noticeably if the supply pipework is undersized. Teeing off close to the rising main minimises the effect.
Can I add a tap to an outbuilding at the same time?
Often yes, but the pipe run should be sized and buried or insulated appropriately for the distance and exposure, so it is worth planning together.
Should the tap be lockable?
On an accessible front elevation it is worth considering, both for security and to stop the supply being used without your knowledge.