How to fix a leaking tap before calling a plumber

A dripping tap wastes about 5,500 litres of water a year. If your house is on a meter (most new London supplies are now metered), that is real money. The fix is usually a 50p rubber washer or a £15 ceramic cartridge. Here is how to do it yourself, and when to give up and call someone.

Diagnose what kind of tap you have

The fix depends on the tap type. Two main kinds in modern London homes:

Compression / washer taps (older style)

The tap you turn multiple times to open. Usually has a separate hot and cold tap rather than a mixer. Common in older houses, especially Victorian and Edwardian properties that have not been updated.

When this type leaks from the spout, the rubber washer at the base of the spindle has perished. £1 in parts, free if you have a spare from a pack of washers.

When it leaks from around the spindle (where the handle meets the body), the gland packing or O-ring has failed. £2 in parts.

Quarter-turn or ceramic disc taps (modern)

The tap you turn 90 degrees to open. Most kitchen mixers and most bathroom taps installed in the last 20 years are this type. Inside is a ceramic cartridge instead of a washer.

When this type leaks from the spout, the cartridge needs replacing. £10 to £25 in parts. Cartridges vary by brand, so it is worth taking the old one to the DIY shop or counter at a plumber's merchant to match it.

When it leaks from around the base, the seals where the spout swivels (on a swivel-spout mixer) have failed. Specific O-ring kits available for most major brands.

How to fix a compression tap (washer change)

You need:

• A new tap washer (buy a multipack of mixed sizes for £3, you will use them again)
• An adjustable spanner
• Possibly a flat-head screwdriver

Steps:

1. Turn off the water. Either the isolator valve under the sink (small slotted screw on the pipe), the kitchen stopcock, or the main internal stopcock. Open the tap to confirm water is off.

2. Cap the plug hole. Drop a small washer or bit of cloth over the plug hole. Stops you losing the screw down the drain.

3. Remove the tap handle. On most older taps, there is either a small screw on top (often hidden under a coloured plastic cap labelled H or C, prise off with a knife), or the whole top unscrews. With the screw out, the handle lifts off.

4. Unscrew the headgear. Underneath the handle is a brass nut (usually 22mm or 24mm). Unscrew anti-clockwise with the spanner. Some are stiff if they have not been moved in 20 years. Penetrating oil and patience.

5. Pull out the spindle. Once the headgear is loose, lift the whole spindle assembly out. At the bottom you will see the rubber washer, held on by a small brass screw.

6. Replace the washer. Unscrew the old washer, fit the new one of the same size, screw back on. Match the diameter (a 1/2 inch tap takes a 1/2 inch washer).

7. Reassemble in reverse. Spindle in, headgear nut tightened (firm but not over-tight, it just needs to seal), handle on, screw in, plastic cap.

8. Turn water back on slowly. Open the tap. Should run clean and shut off cleanly. If it still drips, you have either fitted the wrong size washer or the seat (the brass rim the washer presses against) is corroded. The seat can be ground smooth with a tap reseating tool, but at that point a new tap is often the easier option.

How to fix a ceramic cartridge tap

Ceramic taps are simpler in that they have fewer moving parts, but trickier in that finding the right cartridge requires matching to your exact tap brand and model.

You need:

• A replacement cartridge (best to match exactly)
• An Allen key or screwdriver depending on tap design
• An adjustable spanner

Steps:

1. Turn off the water at the isolator or stopcock.

2. Find the handle screw. Usually hidden under a small coloured cap or label. Prise off with a knife. Underneath is a small Allen screw (commonly 2 to 3mm) or a Phillips screw.

3. Lift off the handle.

4. Unscrew the brass collar holding the cartridge in place. Spanner job.

5. Lift the cartridge out. Take it with you to the DIY shop or merchant counter.

6. Match it. This is the tricky bit. There are dozens of cartridge sizes. Diameter, height, the shape of the bottom (where it interlocks with the tap body), the splines on the top. Take the old cartridge with you. Better still, photograph or note the tap brand and model from underneath the basin (often on a sticker, sometimes engraved into the metal under the spout).

7. Fit the new cartridge. Reverse the steps. Tighten the brass collar firmly but do not crush the cartridge.

8. Test. Water back on, tap operates and shuts off cleanly. If the water dribbles or the handle is too stiff, the cartridge is the wrong fit or has been over-tightened.

When to give up and call someone

A few situations where DIY costs you more than it saves:

• The tap is a high-end designer brand (Hansgrohe, Grohe, Lefroy Brooks). Cartridges and parts can be specific and expensive. Worth a plumber to source the right one first time.
• The isolator valve under the sink does not turn or has snapped.
• The headgear nut on a compression tap will not move with reasonable force.
• The tap body itself is corroded, pitted, or weeping (not a parts repair, needs replacement).
• The tap is on a copper supply that has been disturbed and is now leaking at the joints (you have made a small problem into a bigger one).
• You have done the repair, water is back on, and now there is a drip from somewhere new.

A standard washer or cartridge change in London 2026 is £80 to £150 plus parts. A new tap fitted (you supply the tap) is £100 to £200. A new tap supplied and fitted with a mid-range tap is £200 to £400.

Hard water and London taps

Most of London is hard water. Limescale builds up inside taps the same way it builds up in kettles. Symptoms include slow flow, dribbling instead of streaming, and noisy taps.

Fix: unscrew the aerator at the end of the spout (the small mesh fitting). Soak in white vinegar overnight. Rinse and refit. Restores flow on most blocked aerators in 10 minutes for free. Worth doing on every tap in the house once a year.

If a tap has scaled internally to the point where the cartridge is seized, replacement is the only option.

When you might want a plumber even for a washer

Honest answer: if you have never done it before, are not confident with tools, and the rest of your plumbing is old enough that disturbing it might cause other problems, paying £80 to £150 to get it done quickly and properly might be worth it. I do plenty of "small" tap jobs and most customers tell me afterwards they wish they had not spent two hours of a Saturday on it.

For one tap, DIY makes sense. For three or four taps that all need attention, the cost of paying for an hour of professional time is usually worth the time saved. WhatsApp with a few photos of the taps and I can quote a fixed price for the lot before booking the visit.