How to repair a leaking mixer tap

Guide written by:
Michael, Professional and passionate welder, Sheffield

Michael, Professional and passionate welder, Sheffield

65 guides

A faulty washer is often to blame for a dripping tap. Got an older dual tap mixer? You'll have to inspect the O ring and washer inside your tap as well as those in your tap spout. If you have a single lever mixer, you'll have to replace your cartridge. Read on to find out how to repair a leaking tap.

Important features

  • Isolating your water supply
  • Removing the tap headgear
  • Removing the O rings and washer
  • Fitting the new washers and refitting the tap
  • Checking and replacing the spout washer
  • Changing a tap cartridge

How much does a dripping tap cost?

The financial impact of a leaky tap

It goes without saying that wasting water is an irresponsible use of a valuable resource – but it can also cost you money.

A dripping tap can consume as much as half a litre per hour, which adds up to 12 litres per day and around 4380 litres a year. If you have metered water, the average cost of a cubic metre of water is around £3.19, meaning even a small leak can add up over time.

If you have a bigger leak, or if you have several dripping tapsthis can cost you a lot of money. Some leaky taps can be wasting as much as 5 litres an hour or 120 litres a day!

Identifying the cause of a leak

A dripping tap is often caused by repeatedly turning the tap further than necessary. As the tap washers are constantly being compressed, they can become misshapen. This means that when the tap is not tightened as far as usual, the washer will no longer provide a watertight seal and can let out a trickle of water.

It's worth noting that your tap O rings can be changed when you remove the tap headgear. However, as this part does not move, it is generally kept in better condition than washers. Replacing the O ring is therefore optional but recommended.


  1. Isolating your water supply
  2. Removing the tap headgear
  3. Removing the O rings and washer
  4. Fitting the new washers and refitting the tap
  5. Checking and replacing the spout washer
  6. Changing a tap cartridge

Required skills

Just about anyone should be able to swap out their tap washers. Removing your tap fittings will involve the use of an adjustable spanner and a screwdriver. You'll also have to be able to prise the O rings from the compression valve. You may find you have to reseat your taps. A tap reseater is a plumbing tool designed to clean and smooth down the inside of the tap. You can usually find one for around £10.

Completion time

Approx. 15 to 30 mins

Number of people required

1 person

Tools and equipment

1. Isolating your water supply

Before removing your tap headgear, you will have to cut off the water supply to your dripping tap.

Follow your water lines back to your water meter. You will usually find your outside stop valve around this spot. This will allow you to cut off the water supply to your property.

Isolate your water supply and drain the system by turning on the mixer tap you are looking to repair.

2. Removing the tap headgear

The following advice applies only to dual tap mixers that combine hot water with coldSingle tap mixers are equipped with a removable cartridge instead of a compression valve and washer (see section below).

  • A dual tap mixer features a handle on either side of the tap spoutone supplies cold water and the other provides hot water.
  • If you want to do things properly, it's best to replace the washers in both tap handles.
  • On the top of the taps you will usually find red and blue indices. Carefully remove these using a fine blade slotted screwdriver (there may be a round cap in place of the indices).
  • Underneath the indices you will be able to access the screw holding the tap headgear in place.
  • Holding the tap head in one hand, loosen the screw and remove the headgear assembly.
  • The tap compression valve  will now be exposed and can be removed using an adjustable spanner or a pair of water pump pliers.

3. Removing the O rings and washer

  • With the compression valve now in hand, check the O rings on the body of the valve and the washer mounted at the base.
  • Remove the O rings using the end of a screwdriver.
  • The washer is designed to keep the base of the tap watertight and may or may not feature a hole. Prise the washer off using the end of a screwdriver. Be careful not to injure yourself with the screwdriver!
  • You may be able to dismantle the compression valve and it may feature a number of O rings. You will not normally have to replace all the O rings but be sure to check they are in good condition and apply some silicone grease if necessary. Ensure that all parts are screwed tightly back together to avoid any leaks.
  • Once you have checked everything, screw the lubricated parts back together.

4. Fitting the new washer and replacing the tap

  • By this point, the new O ring(s) should be in place and the headgear should be assembled securely.
  • Next, replace the washer on the base of the valve, making sure the bottom part is clean.
  • Before replacing the headgear, check the tap seat (the threaded surface inside the tap where the washer rests). If damaged, this can also cause leaks. In this case, use a tap reseater to repair the damaged surface.
  • Place the new washer onto the valve and lubricate the assembly before screwing the headgear back into place. Use a spanner to tighten the tap.
  • Replace the tap handle, tighten the fixing screw and insert the indice or plastic cap.
  • Follow the same procedure for the other tap and test the system. Your tap should now be leak-free!

Choosing the right washers

5. Checking and replacing the spout washer

  • It is also possible that your drip is being caused by a leaking tap spout.
  • Check the condition of your O rings by unscrewing the spout using an adjustable spanner. You may want to place a cloth between the spanner and the spout to prevent damage to the unit. Remove the tap spout.
  • Check your O rings for any damage. If they are faulty, remove them as before using a thin blade slotted screwdriver.
  • Worn out O rings will have to be replaced with new, identical ones before you refit your tap spout.

6. Changing a tap cartridge

Alternatively, you may be faced with a leaking single lever mixer. These models features a single handle used to mix hot and cold water together. In this case, you will have to replace the mixer cartridge which keeps the system watertight.

  • You can access the cartridge by removing the small cap found under the lever.
  • Using an Allen key, loosen the fixing screw.
  • Loosen the cartridge using a box spanner.
  • Remove the cartridge and replace it with a new one of the same model.
  • Replace all parts and check your tap for leaks.
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Guide written by:

Michael, Professional and passionate welder, Sheffield 65 guides écrits

Michael, Professional and passionate welder, Sheffield

I was trained as a pipe worker and welder and worked in the industry for 15 years, going all over the UK for large-scale projects. When I decided it was time to stay closer to home - to have time for my own DIY - I took over a local metal shop and eventually went on to become head of a professional engineering firm.

I'm retired now, but I haven't stopped working with my hands. I recently built my own metalwork studio at home - a lifelong dream! I use my welding skills to make sculptures and bespoke furniture. With my studio, I managed to find a piece of paradise where I can let my imagination run wild.

I also love going around to local auctions and boot sales. I always find some interesting old object or tools that I can add to my collection or transform into works of art.

Now that I have the time, I've turned my hand to decorating, painting on canvas and gardening. I'm always developing new technologies and tools to bring my ideas to life. And I'm always happy to give others advice on how they can make their dreams a reality, too!