There is a specific difference between a tap that drips and a tap that leaks, and it decides the whole job.
A tap that leaks around the handle while running has a worn gland or O-ring higher up. A tap that drips from the spout when it is fully closed has failed at the point where it is supposed to seal — a rubber washer pressing down onto a brass ring called the seat, right at the bottom of the tap body.
That second one is this guide. It is the common one, it wastes water continuously, and it costs pennies to fix.
Where a tap actually seals
Step 1 Confirm it drips with the tap fully closed A drip when the tap is off means water is getting past the seal at the bottom of the spindle. Tightening the handle harder will not fix it — it crushes the washer further and wears the brass seat underneath.
Step 2 Turn the water off and plug the basin Use the isolation valve on the pipe under the basin, or the main stop tap. Open the tap afterwards to drain the pipe. Put the plug in — this is how small screws get lost forever.
Step 3 Lift the head assembly out Prise off the hot/cold cap, undo the screw beneath it, lift the handle off, then loosen the large headgear nut with a spanner and unscrew the whole assembly by hand.
Step 4 Replace the washer and inspect the seat Undo the small nut holding the washer to the jumper, fit the new one, and look down into the tap body at the brass seat. Scoring or pitting there is why a new washer alone can start dripping again.
Step 5 Reassemble and turn the water back on slowly Tighten the headgear firmly but not brutally, refit the handle and cap, then open the isolation valve gradually. Run the tap for thirty seconds to clear air, then close it and watch the spout for a minute.
First: which kind of tap do you have?
This matters more than anything else here, because the two types share almost nothing.
- Compression tap — the handle turns several times from off to fully open, and it gets stiffer as you close it. Inside is a rubber washer. This guide.
- Lever mixer / quarter-turn tap — the handle moves 90 degrees and feels the same the whole way. Inside is a ceramic disc cartridge. The fix is to swap the cartridge, not a washer.
If you have to think about it, turn the tap on and count the rotations. Several turns means a washer.
Turning the water off properly
Look under the basin at the pipes feeding the tap. Most have a small isolation valve — a brass fitting with a screwdriver slot. Turn it so the slot lies across the pipe: that is closed.
No isolation valve? You need the main stop tap. Common locations are under the kitchen sink, in an airing cupboard, under the stairs, or in a hallway near the front door. Find it and check it turns before you take a tap apart. A stop tap that has not moved in fifteen years sometimes does not want to.
Then open the tap to drain the pipe, and put the plug in the basin. That second one is not fussiness — the screw inside a tap handle is small, and an open plughole is exactly the right size for it.
Getting the head out
Four moves, in order:
- The cap. The red or blue disc on top of the handle prises off with a small flat screwdriver or a fingernail. Some screw off instead — try turning before you lever.
- The screw. Underneath the cap, usually cross-head. It can be long. Put it somewhere it cannot roll.
- The handle. Lifts straight up. If it is stuck with limescale, wrap it in a cloth soaked in warm water for a few minutes, or gently rock rather than yank.
- The headgear nut. The large hexagonal nut on the tap body. Loosen it with an adjustable spanner, then unscrew the whole assembly out by hand.
The washer, and the part people skip
At the bottom of what you have just removed is the jumper — a small brass disc — with the washer attached under it by a tiny nut. Undo the nut, take the old washer off, and fit the new one. Take the old one with you when you buy replacements so the diameter matches.
A perished washer looks obviously wrong once it is out: hard, cracked, grooved, or squashed out of round.
Now look down into the tap body with a torch. You are looking at the seat — the brass ring the washer lands on. Run a fingertip over it (carefully; old brass can have burrs).
- Smooth → refit and you are done.
- Scored, pitted or rough → a new washer will seal for a few weeks and then start dripping again, and you will conclude the repair failed. It did not; the surface is damaged.
Two fixes for a bad seat, both cheap:
- A reseating tool — a hand tool that screws into the tap body and cuts the brass flat again. A few pounds, one minute of turning.
- Nylon seating washers — a dome of nylon that sits over the damaged seat and moulds to it. Even cheaper and requires no tool, though it is a patch rather than a repair.
Back together
Screw the head assembly back in and tighten the headgear nut firmly but not brutally — snug plus a small nudge. Overtightening distorts the seal and makes the tap stiff for the rest of its life.
Refit the handle, the screw and the cap. Check the handle is in the closed position before you turn the water on, or you will get a surprise.
Open the isolation valve slowly. Run the tap for thirty seconds to push the air out — it will splutter, which is normal. Then close it and watch the spout for a full minute.
When to call a plumber
- The tap body turns with the nut, or the basin moves.
- Water appears under the basin rather than in it.
- The stop tap will not close, or drips once you have used it.
- The tap tail or the pipe below it is corroded green and crumbly.
- It is a mixer with a leaking body rather than a dripping spout.
None of those are washer problems, and all of them get more expensive the longer you improvise.
The steps, in writing
Same sequence as the animation — handy if you'd rather read it, or print it and take it with you.
- Confirm it drips with the tap fully closed A drip when the tap is off means water is getting past the seal at the bottom of the spindle. Tightening the handle harder will not fix it — it crushes the washer further and wears the brass seat underneath.
- Turn the water off and plug the basin Use the isolation valve on the pipe under the basin, or the main stop tap. Open the tap afterwards to drain the pipe. Put the plug in — this is how small screws get lost forever.
- Lift the head assembly out Prise off the hot/cold cap, undo the screw beneath it, lift the handle off, then loosen the large headgear nut with a spanner and unscrew the whole assembly by hand.
- Replace the washer and inspect the seat Undo the small nut holding the washer to the jumper, fit the new one, and look down into the tap body at the brass seat. Scoring or pitting there is why a new washer alone can start dripping again.
- Reassemble and turn the water back on slowly Tighten the headgear firmly but not brutally, refit the handle and cap, then open the isolation valve gradually. Run the tap for thirty seconds to clear air, then close it and watch the spout for a minute.
Questions people actually ask
My tap has a single lever, not a screw handle. Does this work?
No. A lever mixer uses a ceramic disc cartridge rather than a rubber washer, and the fix is to replace the whole cartridge rather than a washer. The disassembly is similar — cap, screw, handle, retaining nut — but you lift out a cartridge and buy a matching replacement. Take the old cartridge to the shop; they are not interchangeable between brands.
I replaced the washer and it still drips.
Almost always the seat. The brass ring the washer presses onto gets scored by grit over the years, and a perfect washer cannot seal against a damaged surface. A tap reseating tool cuts it flat again for very little money, and nylon seating washers are an easier alternative that mould themselves to the damage.
Where is my isolation valve?
On the pipe under the basin, usually a small brass fitting with a slot for a flat screwdriver. A quarter turn so the slot sits across the pipe means closed. If there is not one, you need the main stop tap — commonly under the kitchen sink, in an airing cupboard, or where the supply enters the house. Find it before you start, not after.
The headgear nut will not move.
Hold the tap body steady with a second spanner or a gloved hand so you are not twisting the whole tap against the basin — that is how you crack a basin or break the tail underneath. Penetrating oil and a fifteen-minute wait helps. If it still will not move, stop; a seized tap is a plumber job, not a fight.
Does a dripping tap actually waste much water?
Yes. A steady drip runs into thousands of litres a year, and on a hot tap you are also paying to heat every drop of it. It is one of the cheapest repairs in the house relative to what it saves, which is why it is worth doing the week you notice it rather than the year you notice it.