How to Fix a Leaky Tap

Before you start: isolate the water

Look under the basin or sink for a small valve on the supply pipe (a screw-slot or quarter-turn lever). Turn it off. If there is no isolation valve, close your main stopcock — typically under the kitchen sink in London flats and houses.

Which tap do you have?

• Traditional pillar taps (separate hot/cold, twist 2–3 full turns) — use a rubber washer.
• Quarter-turn / ceramic disc taps (modern, lever style) — use a ceramic cartridge.
• Monobloc mixer (single lever, kitchen) — use a single cartridge with two seals.

Fixing a traditional pillar tap

1. Pop off the H/C top cap, unscrew the headgear screw, lift the handle.
2. Use a spanner on the brass headgear nut to lift the body out.
3. The washer is on the underside — replace like-for-like (½-inch or ¾-inch).
4. If the seat is pitted, regrind it with a tap-seat reseating tool (£8).

Fixing a quarter-turn ceramic tap

1. Lever off the cap, undo the grub screw, remove the handle.
2. Unscrew the ceramic cartridge — note hot vs cold (red ring = hot).
3. Replace with a matching cartridge (take the old one to a plumbers merchant).

Fixing a leaking monobloc mixer

1. Drip from the spout = cartridge worn → replace the single mixer cartridge.
2. Drip from the base of the spout = O-rings under the spout — replace the two black O-rings.
3. Drip under the sink = compression nuts on the flexi tails — tighten a quarter-turn, then renew the flexi if still leaking.

Reassembly checklist

• Reverse the steps without overtightening — porcelain handles crack easily.
• Reopen the supply slowly, watching the spout for leaks.
• Test hot and cold separately and check under the basin with kitchen roll.

When to call a plumber

If the head is seized, if the seat is corroded, or if the flexi tails are weeping at the body, replacing the whole tap is faster. London fitted price: £80–£160 labour + tap.