How to Fix a Dripping Tap

A tap dripping once a second wastes thousands of litres a year. On a metered supply that is real money, and the fix is usually straightforward.

Most drips come down to one worn part that you can replace with basic tools. This guide covers traditional taps and modern mixer taps, and the point where it makes more sense to stop and call a plumber.

Why taps drip

• A worn washer, which is the most common cause on traditional taps
• A damaged O-ring, the small rubber seal
• A corroded valve seat, where the tap meets the spout
• A worn cartridge, which is the usual culprit on modern mixer taps
• High water pressure, which stresses the internal components
• General wear from years of use

Hard water across Crawley, Horsham and Redhill accelerates all of this.

Traditional tap or mixer

If the handle takes a full turn or more to go from off to fully on, it is almost certainly a traditional tap with a rubber washer inside. If it goes from off to full in a quarter or half turn, or it is a single lever, it has a cartridge instead. The repair is different for each, and both are covered below.

Where the water is coming from

• From the spout with the tap turned off. The washer on a traditional tap, or the cartridge on a mixer.
• From around the handle while the tap is running. Usually a worn O-ring.
• From the spout even after a new washer. The valve seat is probably worn or corroded.
• From the base of the tap. A failed seal inside the body or on the connections underneath. This one is usually better left to a plumber.

What you need

An adjustable spanner, screwdrivers, replacement washers, a cloth, and a small container for the parts. Penetrating oil and plumber’s grease are useful if you have them.

It also helps to have a torch for looking into the tap body, a couple of spare O-rings, and both flat and cross-head screwdrivers. Buy washers in a few sizes, since you will not know which one you need until the old one is out. For a mixer tap you will probably need an Allen key as well.

One genuinely useful tip: photograph each stage as you take it apart. Reassembly is much easier with pictures.

Fixing a traditional tap

1. Turn the water off. Isolation valve under the sink, turned clockwise, or the main stopcock if there is no isolation valve. If the isolation valve has a screwdriver slot rather than a handle, turn it a quarter turn so the slot sits across the pipe. Open the tap to drain it, and put the plug in so you do not lose small parts down the waste.

2. Remove the handle. There is usually a small screw on top or at the base, often hidden under a decorative cap you can gently prise off. Put the screw straight into your container, because it is tiny and easy to lose.

3. Remove the headgear. Cover the large nut with a cloth to protect the chrome, then turn it anticlockwise with the spanner. If it is stuck, apply penetrating oil and wait ten minutes rather than forcing it. Once the nut is free, lift out the valve assembly.

4. Replace the washer. It sits at the bottom of the valve held by a small nut. Clean the area and fit a new washer of the same size. It should sit snugly. A loose or wrong-sized washer will drip straight away.

5. Check the O-ring around the valve body. Replace it if it looks worn or cracked, and put a little plumber’s grease on the new one.

6. Reassemble in reverse. Tighten the headgear firmly but do not overtighten. Refit the handle and any decorative cap.

7. Test. Turn the water back on slowly, check for leaks around the base, and work the tap a few times. Watch it for a few hours.

Fixing a modern mixer tap

Mixer taps use a cartridge rather than a washer, and they are actually easier.

1. Turn off both hot and cold supplies
2. Remove the handle, usually held by a grub screw needing an Allen key
3. Unscrew the retaining nut holding the cartridge
4. Pull out the old cartridge, noting its orientation
5. Fit the new one the same way round, hot and cold correct
6. Reassemble and test

Photograph the old cartridge in place before you pull it out. Fitting a new one the wrong way round swaps your hot and cold.

Cartridges are brand specific. Take the old one to a plumbing supplier rather than guessing.

When to stop and call someone

• It still drips after replacing the washer
• You cannot identify the right replacement part
• The mechanism is corroded or seized solid
• You have damaged something taking it apart
• Water is leaking from the base of the tap rather than the spout
• Several taps are dripping, which suggests a pressure problem rather than worn washers
• There is no isolation valve and you would rather not shut off the whole house
• You are simply not comfortable taking a tap apart

For a plumber, most dripping taps are a thirty to sixty minute job. If you would rather not do it yourself, it is a routine part of our plumbing repairs work.

Preventing the next one

• Do not overtighten. Cranking a tap shut hard is what destroys washers.
• Replace washers every two to three years as maintenance rather than waiting for the drip
• Clean the aerators quarterly to stop mineral build-up
• Check your water pressure, since high pressure stresses everything
• Use decent replacement parts, not the cheapest available

The aerator is the small mesh insert screwed into the end of the spout. Unscrew it, clear the scale out of the mesh, and screw it back in.

What a drip actually costs

A single drip does not look like much, but it runs all day and all night. One drip a second adds up to thousands of litres over a year, and a fast drip wastes a great deal more.

On a water meter, you pay for every litre of it, so fixing it quickly pays for itself. Even if you are not metered, it is treated drinking water going straight down the drain.