Exclusive app offer: free delivery on orders over £200*Terms & conditions apply
Who are we
How to repair a leaking mixer tap

How to repair a leaking mixer tap

Michael, Professional and passionate welder, Sheffield

Guide written by:

Michael, Professional and passionate welder, Sheffield

95 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 tap, 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
Shop our plumbing washers

The financial impact of a leaking tap

It goes without saying that wasting water is an irresponsible use of a valuable resource – but it can also cost you a lot of 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 cause a big water bill over time.

If you have a bigger leak, or if you have several dripping taps, you're going to be paying a lot of money for nothing at all. 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 dealing with compression, they can get 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 without calling a plumber. 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

Explore the ManoMano catalog
Box spanners

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.

Explore the ManoMano catalog
Water meters

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 spout: one 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 head in one hand, loosen the screw to remove the headgear assembly.
  • The tap compression valve will now be exposed and can be removed using an adjustable spanner or water pump pliers.
Explore the ManoMano catalog
Combination pliers

  • 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 tip 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.
Explore the ManoMano catalog

  • 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

  • It's important to replace your O rings and washers with identical ones in a new condition.
  • You can measure these parts using a tape measure or, better still, callipers.
  • If you don't have either of these, take your washers along to a DIY shop to find replacements.
Explore the ManoMano catalog
  • 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 should 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 ones before you refit your tap spout.

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.
  • Use an Allen key to 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.
Explore the ManoMano catalog
Allen keys

Shop our plumbing washers

Guide written by:

Michael, Professional and passionate welder, Sheffield, 95 guides

Michael, Professional and passionate welder, Sheffield

I was trained as a pipe worker and a pipe-welder and after having travelled for 35 years working around the UK, I became the head of a metal shop, then a designer and in the end the head engineer. I have designed and built a workshop where I make metal sculptures: I managed to find a piece of paradise where I can let my imagination run wild. Auctions and garage sales are no secret to me. I find unusual objects and old tools there that I collect or transform into works of art. I also like decoration, painting on canvas, and gardening. I am developing new technologies concerning tools. To share my passion and advise you in your choice of materials is a real pleasure.

  • Millions of products

  • Delivery to your home or click & collect

  • Hundreds of dedicated experts online