Use this guide when a tap keeps dripping after it is turned off firmly. You will need a flat screwdriver, an adjustable spanner, a cloth, and ideally a replacement washer or cartridge matched to your tap.
Step by step
Identify the tap type
Turn the tap on and off and note how far it moves. If it turns several times before stopping, it is usually a compression tap with a rubber washer. If it turns only a quarter or half turn, it usually has a ceramic disc cartridge. Mixer taps with a single lever normally use a cartridge too.
Isolate the water
Look under the sink for a small isolation valve on the pipe to the tap and turn the screw slot a quarter turn so it sits across the pipe. If there is no isolation valve, turn off the internal stop tap. Open the tap to drain the remaining water and put the plug in so small parts cannot fall down the drain.
Take the tap apart
Prise off the decorative cap or lever and undo the screw beneath it. Use an adjustable spanner, with a cloth to protect the finish, to unscrew the headgear or cartridge body. Lay the parts out in order on a towel and take a photo so you can reassemble them correctly.
Replace the worn part
For a compression tap, remove the old rubber washer from the bottom of the headgear and fit a new one of the same size. For a cartridge tap, take the old cartridge to a plumbers' merchant or DIY shop to match it exactly, as sizes and spline counts vary. Check the O-rings for cracks and replace them if they look flattened or worn.
Reassemble and test
Refit the parts in reverse order, tightening firmly but not forcefully, especially on ceramic cartridges. Remove the plug, slowly reopen the isolation valve or stop tap, and let the tap run to clear air. Turn it off and watch for drips for a few minutes, and check under the sink for any leaks.
Ready-to-use checklist
- Tap type identified
- Isolation valve or stop tap turned off
- Plug in the sink to catch small parts
- Photo taken of parts before removal
- Matching washer or cartridge ready
- O-rings checked and replaced if worn
- Water back on and no drips after testing
Practical tips
- Take the old washer or cartridge with you when buying a replacement so you get an exact match first time.
- Wrap spanner jaws in a cloth or tape to avoid scratching chrome finishes.
- A small smear of plumber's silicone grease on new O-rings makes the tap turn smoothly and helps them seal.
Common problems
The tap still drips after replacing the washer.
The brass seat the washer presses against may be worn or pitted. A seat-reseating tool or a slip-on washer and seat kit can help, but if the tap body is badly worn it is often simpler to replace the whole tap.
Water leaks from around the handle rather than the spout.
This usually means worn O-rings or a loose gland nut around the spindle. Tighten the gland nut slightly or replace the O-rings on the headgear or cartridge.
The headgear will not unscrew.
Hold the tap body steady with one hand or a second spanner so you do not twist the tap or strain the pipework. A little penetrating oil left for ten minutes can help, but if it still will not move, call a plumber rather than risk cracking the sink or fitting.