How do I replace a flexible tap connector?

Flexible connectors are convenient and are a well-known cause of major water damage, because the braided ones corrode invisibly and then fail all at once at mains pressure.

Safety

What you'll need

• Replacement flexible connector of the correct length and thread
• Adjustable spanner or a basin wrench
• PTFE tape for the compression end only
• Towels, bowl and a torch

Step by step

1. Inspect the existing ones for warning signs.Rust staining on the braid, kinks, bulges, green corrosion at the fittings, or any damp around the ends. A braided connector that looks rusty is close to failing and should be changed now.
2. Replace them on age as well.Ten years or so is a reasonable working life. Replacing a pair proactively costs very little against the cost of a mains-pressure failure into a kitchen unit.
3. Turn the water off and drain down.At the isolating valve if there is one, otherwise the stopcock. Open the tap to release the pressure and let the pipe drain, and have a bowl underneath.
4. Measure the existing connector before buying.Length nut-to-nut, and both thread types. Too short and it strains; too long and it kinks. Take the old one to the shop if you can.
5. Check the thread sizes.Usually 15mm compression at the pipe end and 1/2 inch BSP female at the tap. Monobloc mixers often use 10mm compression tails, which need a different connector entirely.
6. Choose a good-quality one.WRAS-approved, from a plumbers' merchant rather than the cheapest available. This is the fitting that fails catastrophically, and the price difference is a couple of pounds.
7. Remove the old one carefully.Support the tap tail while undoing the nut. Twisting a tap tail under a basin can crack a ceramic basin or damage the tap.
8. Check the tap tail and the seal seat.Clean any old debris and check the sealing face is undamaged. A scored or corroded seat will leak with any connector.
9. Fit the tap end with no PTFE tape.It seals on a rubber washer inside the nut. Tape on that thread does nothing useful and can hold the washer off its seat. Make sure the washer is present and seated.
10. Use PTFE only on a threaded compression end where appropriate.The compression end seals on the olive rather than the thread. A few turns of PTFE round the olive is a common belt-and-braces measure but the joint should seal without it.
11. Do not overtighten.Hand tight then about a quarter turn with a spanner at the tap end. Overtightening crushes the rubber washer and is the most common cause of a new connector leaking.
12. Avoid kinks and sharp bends.The hose should curve gently with no tight bends or twists, and should not be stretched taut or coiled up. Kinks are where braided hoses fail.
13. Turn on slowly and check thoroughly.Gradually, then dry everything and wrap kitchen roll round both ends. Check after an hour and again the next day.
14. Fit isolating valves at the same time.If there are none, this is the moment. It makes every future job on that tap trivial and it lets you shut off quickly if a connector ever does fail.
15. Check them annually.A torch under the sink once a year looking for rust and damp. It is two minutes and it catches the failure before it happens.

Tips

• No PTFE tape at the tap end. It seals on a rubber washer, and tape there can hold the washer off its seat.
• Replace braided connectors on age, not only on failure. Ten years is a sensible limit and the replacement costs a few pounds.
• Take the old connector to the merchant. Thread sizes vary and monobloc taps use different tails entirely.

Common mistakes

• Overtightening the tap-end nut — It crushes the rubber washer, which then leaks. Hand tight plus about a quarter turn is enough, and further tightening makes it worse.
• Leaving an old or rusty braided connector in place — They fail suddenly at full mains pressure, usually with nobody home. It is among the most common causes of serious water damage in houses.

If it doesn't work

Questions people ask