How to Fix a Dripping Tap: Washers, Cartridges and Mixer Taps

A dripping tap is one of the most common household annoyances, and one of the most wasteful. A drip that seems harmless continues every minute of every day, wasting water — and if it is the hot tap, wasting the energy used to heat that water as well. Many drips are caused by a small worn part that costs very little to replace, and with basic tools and some care, most people can fix a dripping tap themselves in under an hour.

This guide explains how to identify the type of tap you have, how to isolate the water safely, and how to replace the parts that usually cause drips. If at any point you are unsure, stop and call a qualified plumber — a flooded kitchen costs much more than a call-out.

Why taps drip

A tap controls water by pressing a seal against a valve seat. Over time, that seal wears out, hardens or becomes damaged by limescale and grit, so water seeps past even when the tap is turned off. The most common culprits are:

• A worn rubber washer in a traditional compression tap.
• A worn or damaged ceramic disc cartridge in a quarter-turn or mixer tap.
• Worn O-rings, which cause leaks around the spout or the base of the handle rather than from the spout itself.
• A damaged valve seat, the surface the washer presses against, which can be pitted by grit or limescale.
• Limescale build-up in hard-water areas.

Where the water is coming from gives a clue:

• Dripping from the spout when the tap is off usually means a worn washer or cartridge.
• Water around the base of the spout on a swivel-spout mixer usually means worn O-rings.
• Water leaking from under the handle may mean a worn gland packing or O-ring on the spindle.

Identify your tap type

Compression taps

Traditional taps with separate hot and cold handles that you turn several times to open fully are usually compression taps. They use a rubber washer pressed down onto a seat, and the handle often feels progressively tighter as you close it. These are the easiest to repair.

Quarter-turn (ceramic disc) taps

Taps that go from fully off to fully on in a quarter or half turn use ceramic disc cartridges. Two ceramic discs with holes slide against each other to open and close the flow. When they leak, the whole cartridge is usually replaced.

Mixer taps

Mixer taps combine hot and cold water through one spout. They may have two handles (each controlling a cartridge or washer) or a single lever (a monobloc or single-lever mixer, which typically uses one ceramic cartridge to control both temperature and flow).

Look carefully at your tap, check any manufacturer's markings, and search for the model's instructions if you can find them. Taking a clear photo before you start is very useful.

What you will need

• Adjustable spanner or the correct size of open-ended spanner.
• Screwdrivers, flat-head and cross-head.
• Hex keys (Allen keys), as many lever handles are held on by a small grub screw.
• Replacement washer, cartridge or O-rings — ideally, take the old part to a plumbers' merchant or hardware shop to match it exactly.
• An old towel or cloth to protect the sink and wrap around chrome parts so the spanner does not scratch them.
• Silicone grease suitable for taps (often sold for plumbing use).
• A plug for the sink, so small parts cannot fall down the drain.
• Penetrating oil for stiff fittings, and limescale remover if your area has hard water.

Step one: isolate the water supply

Never start dismantling a tap without stopping the water first.

1. Look for an isolation valve on the pipe under the sink, leading to the tap. It often has a small slot that you turn a quarter turn with a flat-head screwdriver so the slot is across the pipe, or a small handle. This is the easiest option, because it affects only that tap.
2. If there is no isolation valve, turn off the main stopcock, usually found under the kitchen sink, near where the water supply enters the home, or in a utility area. Some homes with stored hot water have separate valves for hot water supplies; if you are unsure, ask a plumber.
3. Open the tap fully to drain any remaining water and confirm the supply is off.
4. Put the plug in the sink and lay a towel in the basin.

It is a good idea to find and test your stopcock before you ever need it in an emergency.

Fixing a compression tap: replacing the washer

1. Remove the handle. Many handles have a decorative cap on top that prises or unscrews off to reveal a screw. Remove the screw and lift off the handle. Some older taps have a shroud that unscrews by hand.
2. Unscrew the headgear. Using a spanner on the large nut at the base of the tap mechanism, turn it anticlockwise. Hold the tap body steady with your other hand so you do not twist the tap or its pipework. Wrap the spanner jaws in a cloth to avoid scratching chrome.
3. Remove the old washer. The washer is on the bottom of the headgear. It may be held on by a small nut or simply pressed onto a button.
4. Fit the new washer, of the same size and type, and secure it.
5. Check the valve seat inside the tap body. If it is rough or pitted, a new washer may not seal properly; seats can sometimes be re-ground with a special tool or covered with a seat-and-washer replacement kit, but if in doubt, ask a plumber.
6. Reassemble the headgear, tightening firmly but not excessively, then refit the handle.
7. Turn the water back on slowly and test.

Fixing a quarter-turn or mixer tap: replacing the cartridge

1. Remove the handle or lever. Look for a small grub screw at the back or underneath, often hidden behind a coloured hot/cold indicator cap. Loosen it with a hex key and lift off the handle.
2. Remove any shroud or cover to expose the cartridge.
3. Note the cartridge's orientation before removal — take a photo. Some cartridges must be fitted in a particular position, and on hot/cold taps the hot and cold cartridges may turn in opposite directions.
4. Unscrew the cartridge with a spanner, holding the tap body steady.
5. Take the old cartridge to a shop to find an exact match. Cartridges vary in size, spline pattern (the teeth the handle grips) and rotation; the wrong one will not fit or seal.
6. Fit the new cartridge in the same orientation, tightening firmly by hand and then gently with the spanner. Over-tightening can crack ceramic parts.
7. Reattach the handle and turn the water on slowly to test.

Sometimes a cartridge that drips is simply clogged with grit or limescale. Cleaning it and the tap body with limescale remover can help, but if the ceramic discs are scratched, replacement is the reliable fix.

Fixing leaks around the spout: replacing O-rings

On a swivel-spout mixer, water appearing around the base of the spout usually means worn O-rings.

1. Isolate the water and open the tap to drain.
2. Remove the spout. Depending on the design, it may lift off after loosening a grub screw, or unscrew from the tap body.
3. Remove the old O-rings from the grooves, using a blunt tool so you do not scratch the surfaces.
4. Fit matching new O-rings, lightly coated with tap-safe silicone grease.
5. Refit the spout, turn the water back on, and test.

If the tap still drips

If a new washer or cartridge does not stop the drip:

• Check you fitted the correct part in the right orientation.
• Inspect the valve seat for damage.
• Check for limescale inside the tap body.
• Consider replacing the tap. If the tap is old, corroded or repeatedly fails, a new tap may be the better long-term solution — and modern taps with aerators can also reduce water use.

Preventing future drips

• Do not over-tighten taps when turning them off. Firm is enough; forcing them wears washers faster.
• Deal with limescale regularly in hard-water areas by cleaning aerators and visible fittings.
• Fix drips early, before grit damages the valve seat.
• Keep a spare washer and O-ring kit for your tap types; they cost little and save a second trip to the shop.

When to call a plumber

Call a qualified plumber if:

• You cannot find a way to isolate the water.
• Fittings are badly corroded or seized and might break if forced.
• The leak is from pipework, not the tap itself.
• You are unsure about the tap type or the parts needed.
• Water is leaking under the sink or into cupboards.
• The repair involves soldering, pipe cutting or the hot-water cylinder.

There is no shame in calling a professional for a tricky fitting; the aim is to save money, not to risk a flood.

How much water does a drip waste?

The amount varies with the size and speed of the drip, but because it continues around the clock, even a modest drip can waste a surprising amount over a year. You can measure your own: place a measuring jug under the tap for ten minutes, then multiply up to estimate the daily and yearly waste. If you have a water meter, the savings appear directly on your bill — and for a hot tap, on your energy bill too.

A quick checklist

1. Identify where the water is coming from.
2. Identify the tap type.
3. Isolate the water and drain the tap.
4. Protect the sink and plug the drain.
5. Remove the handle and headgear or cartridge.
6. Take the old part to the shop to match it.
7. Fit the new washer, cartridge or O-ring.
8. Reassemble, restore the water slowly and test.

The bottom line

A dripping tap is usually caused by a small, cheap part that has worn out. With the water safely isolated, a few basic tools and the correct replacement, most compression, quarter-turn and mixer taps can be repaired in less than an hour. Fixing the drip saves water and energy, stops the irritating sound, and builds the confidence to tackle other small jobs around the home — while knowing when to call a plumber keeps a simple repair from becoming an expensive one.