Outside Taps: Fitting, Frost Protection and Fixes
Everything about outside taps in UK homes: how they are fitted, why they need a double check valve, winter protection and fixing a leak or drip.
An outside tap is handy for the hose, the car and the watering can, but it is also one of the most exposed bits of plumbing in the house. It sits in the cold, it is often forgotten, and it connects directly to your drinking water supply. A little understanding goes a long way to keeping it trouble free.
How an outside tap is usually supplied
Most outside taps are fed from the mains cold water, taken from a pipe inside the house, passing through the wall and ending at a bib tap. A well-installed one includes:
- An isolation valve inside the house, so that you can turn the supply off in winter.
- A drain-off point or a small drain tap next to the valve, so the outside pipe can be emptied.
- A double check valve, either built into the tap or fitted in line, to stop dirty water flowing back into the mains.
That last point matters. If you attach a hose to an outside tap and leave the end in a pond, paddling pool or bucket, water could be drawn back into the supply. The Water Regulations require backflow protection for this reason. See water regulations in plain terms.
Fitting a new outside tap
Adding a tap involves drilling through the wall, tapping into a suitable supply and fitting a valve. It is a job for a competent DIYer or plumber, and it is wise to use one who understands the rules on backflow. Points to settle first:
- Which supply to use, as taking it from a drinking-water pipe is usual.
- Where the wall allows a clean hole at a slight downward slope outward.
- Whether a double check valve is included or needs adding.
- How you will isolate and drain it each winter.
Typical labour is not large, but running a new pipe from a distance adds time. See how much a plumber costs for the wider picture.
Winter protection
A full pipe that freezes can split and then leak inside the wall when it thaws. Every autumn:
- Disconnect hoses and any splitters.
- Close the isolation valve inside the house.
- Open the outside tap to let the water out.
- Use the drain-off cap to empty the pipe, if fitted.
- Leave the outside tap slightly open so any trace of water can expand harmlessly.
- Fit an insulated tap cover if you like, as extra protection.
If you want to understand what happens when things go wrong, see frozen and burst pipes.
Common problems and fixes
Dripping spout
Often a worn washer. The repair is similar to an indoor tap. Our guide to fixing a dripping tap covers it.
Leak from the handle
A worn gland or packing nut. Tighten the nut a little, and replace the packing if needed.
Leak behind the tap
If water appears inside the wall or on the floor beneath the tap, turn off the supply and call a plumber. This could be a damaged fitting inside the wall.
Low flow
Blocked filters, limescale or a part-closed valve. Check the isolation valve inside the house.
Safe use of a hose
- Do not leave a hose submerged.
- Use a hose-union backflow preventer, if recommended.
- Disconnect after use.
- Never use a hose to fill a garden pond or hot tub without proper protection.
Worked example: the autumn shut-off routine
A homeowner with a bib tap on the back wall spends ten minutes each October. They unscrew the hose and any connector, turn off the small isolation valve inside the utility room, open the outside tap, then open the drain cap to let the last water out. Finally they close the outside tap again and leave the drain cap off, or fit an insulated cover. In spring they reverse the steps, check for drips and enjoy a trouble-free summer. It is a tiny routine that avoids a burst pipe inside a wall.
Choosing a tap type
| Tap type | Good for | Watch out for |
|---|---|---|
| Standard bib tap | General garden use | Needs a double check valve added |
| Bib tap with built-in check valve | Convenience and compliance | Slightly higher price |
| Frost-protected or long-stem tap | Cold exposed sites | Needs correct fitting |
| Lockable tap | Shared or accessible areas | Keep the key safe |
Special cases
- Flats and shared gardens. Outside taps may belong to the building. Ask the managing agent before changes.
- Rentals. Do not drill through walls without permission. Report a leaking tap to the landlord.
- Older homes. Solid brick or stone walls need careful, clean drilling and a suitable sleeve.
- Hot tubs, ponds and paddling pools. These are exactly where backflow protection matters most.
Questions to ask a plumber
- Does the tap include a double check valve?
- Where is the isolation valve and drain point?
- How will the pipe be insulated where it passes through the wall?
- Is the route accessible for future repair?
A leak you should not ignore
If you see damp patches inside the house under an outside tap, treat it as a burst until proven otherwise. Shut the isolation valve, drain the pipe and ask a plumber to check. A small repair is far cheaper than repairing plaster and a skirting board.
Frequently asked questions
Do I need a double check valve on an outside tap?
Yes, it is generally required. Many modern outside taps include one built in. If yours does not, a plumber can add one.
Can an outside tap be fed from the kitchen sink pipe?
Often this is the usual route, but it needs an isolation valve and drain point. The pipe route should be sensible and insulated.
Why does my outside tap leak when it is cold?
Water may have frozen and expanded, damaging the pipe or fittings. Switch off and ask a plumber to check before the thaw makes it worse.