Why is my tap leaking from the base of the spout?

Most kitchen and many basin mixers have a spout that swivels on the body, sealed by two O-rings on the spout's shank. Those O-rings wear from turning and harden with age, and when they go the leak appears at the joint or, more often, runs down inside the tap and onto the worktop.

What you'll need

• Replacement O-rings, sized to the spout
• Silicone tap grease
• An Allen key or small screwdriver
• A cloth

Step by step

1. Confirm where the water is coming from.Dry everything, run the tap, and watch. Water welling up at the spout base means the O-rings. Water dripping from the spout outlet means a washer or cartridge, which is a different repair.
2. Check the worktop underneath.Very often the water is not visible at the top at all — it runs down the inside of the body and appears in the cupboard. A wet cupboard base with a dry spout still points at the spout seals.
3. Turn the water off at the isolating valves.There should be one on each supply under the sink. Open the tap afterwards to prove they have shut and to relieve pressure.
4. Find the retaining screw or clip.Most swivel spouts are held by a small grub screw at the back of the body, a circlip inside, or a threaded collar. Look before pulling.
5. Lift the spout off.Twist gently and pull straight up. Scale often holds it; a soak with descaler around the joint and patience is better than force.
6. Remove and match the O-rings.There are usually two, sitting in grooves on the shank. Roll them off and take them to a merchant, or buy an assorted tap O-ring pack — they are pennies.
7. Clean the bore of the tap body.Scale inside the body cuts the new O-rings on the way in. Wipe it out and descale it if it feels rough.
8. Grease with silicone tap grease only.Silicone grease on the new O-rings makes them slide in without rolling or tearing. Never use petroleum jelly, which swells and destroys rubber seals.
9. Refit and test at full flow.Push the spout down fully, refit the retaining screw, and run it hot and cold at full flow while watching the base and the cupboard below.

Tips

• Buy an assorted O-ring pack rather than trying to identify one size. It costs very little and saves a second trip.
• If the spout was very hard to remove, descale the body bore while it is apart — it will be easier next time.
• Check the cupboard base for swelling. A slow spout leak often damages chipboard long before anyone notices the tap.

Common mistakes

• Replacing the tap washer for a leak at the base — The washer seals the flow of water through the valve. It has nothing to do with the joint between spout and body, so replacing it changes nothing.
• Lubricating O-rings with petroleum jelly — Hydrocarbon greases swell nitrile and EPDM rubber. The O-ring distorts, will not seat, and fails within weeks.

If it doesn't work

Questions people ask