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how to change bath taps

How to Change Bath Taps: Step by Step Help Guide

Last updated on January 31st, 2024

Learning how to change bath taps or bath fillers can be difficult. For the most part, bath taps are a lot harder to access than other taps, especially if there is a unit very close to it.

Changing basin taps can be a lot easier as it’s much more accessible to get under a bathroom sink than a bath.

I have been a full-time plumber for over a decade and changing bath taps is definitely harder than changing a kitchen tap most of the time.

Here I’ll give you my best advice for replacing bath taps and any other parts of a bath tap you might need to replace.

Bath Tap Fitting Tools

These are the bath tap fitting tools I need on most bath tap replacement jobs. The bath tap tightening tool, or a standard tap backnut box spanner, is 27 mm at one end and 32 mm at the other.

The 32 mm end will be suitable for changing almost all bath taps, and the 27 mm end will be suitable for changing bathroom sink taps.

If there are no flexible tap connectors on the old bath taps, then you will also need a pipe cutter or two (15 mm and 22 mm) to cut the pipes and fit isolation valves for the new flexible tap connectors to connect to.

How to Remove a Bath Tap

  • Isolate the water supply to the bath taps using isolating valves on the bath tap pipes or the main stopcock.
  • Open the bath taps and the other taps in the property to get rid of the water from the pipes.
  • Put a towel down under the bath taps to catch any water.
  • Cut the copper pipes if there aren’t any flexible tap connectors on the old taps.
  • Turn the nut on the bottom of the tap threads anti-clockwise with an adjustable spanner and pull the pipes to the side.
how to remove bath taps
How to remove a bath tap

  • Remove the tap connectors and any pipes you might have cut.
  • Push a backnut box spanner over the tap threads and over the backnuts securing them to the bath, and turn them anti-clockwise to unscrew and remove both backnuts.
  • Pull the bath taps or bath filler mixer tap out of the holes.

How to Fit a Bath Tap

  • Fit the new bath tap into the holes in the bath with any foam or rubber seals supplied, and screw the backnuts on from underneath.
how to fit a bath tap
How to fit a bath tap

  • Tighten with the backnut tap tightening tool, the large end of the box spanner.
  • Screw on the flexible tap connectors to the tap threads and tighten with an adjustable spanner.
  • If you had to cut the pipes, then you should fit some new flexible tap connectors.
  • Close all the taps in the property and turn the water supply back on and check for leaks.

How to Change Bath Taps Without Removing Bath

As a plumber, I would always advise against fitting taps in the middle of a bath if the bath is going to be against a wall, but I do come across them.

Once a person finds out that to change bath taps you have to remove the bath, it’s always too late.

If you have a bath with the tap in the middle against a wall, here are your options:

  1. Go through the wall
  2. Use a skinny plumber
  3. Have a special tap

Go Through the Wall

To change the bath taps without removing the bath, you have to make a big hole in the wall that the bath is against to access the bath tap and pipes underneath the bath. This can be a plasterboard wall, or worst case a brick wall.

I have gone through a few plasterboard walls from the bedroom next door to change a bath tap, but never had anyone wanting me to go through their brick wall, unsurprisingly. A plasterboard wall can be patched back up.

Use a Skinny Plumber

Another possible way to change a bath tap without removing the bath is to use a small, skinny plumber (not joking), to squeeze under the bath.

I don’t fall in this category, but there are some out there and I’ve seen videos of them doing it.

Fit a Special Bath Tap When Fitting the Bath

Not much help when you’re replacing your bath tap but there are special bath taps you can buy now where you can change the main part of the bath tap from above the bath after the tap is fitted.

I haven’t come across any or fitted any. These would have to be fitted when the bath is fitted.

How to Change Bath Tap Parts

You don’t always need to replace a bath tap when you have problems with it, here are the parts of a bath tap that can be replaced:

How to Change a Bath Tap Head

To change a bath tap head, you need to find the screw keeping it fixed to the bath tap. This is normally covered with a plastic cap which can be screwed off or pulled off with a small flathead screwdriver.

Once this is removed, you can loosen the screw holding the head on the tap. This is normally a grub screw that takes a 2.5 mm Allen key. Once this is loose, the head or handle should just pull off the bath tap. Then fit the new bath tap head.

How to Change a Bath Tap Cartridge

To change a bath tap cartridge, you need to remove the head or handle as above, and then you will need to unscrew the brass cartridge anti-clockwise using an adjustable spanner.

If they are two separate bath taps on a tap cartridge replacement job, you might need to hold the tap still with some large water pump pliers or a pipe wrench, whilst you turn the cartridge out.

These can be very stiff on old bath taps. Once out, just screw the new cartridges in and tighten them up with a spanner.

How to Change a Bath Tap Washer

if you need to fix a dripping tap, then changing the tap washer might be a solution. You can only change a bath tap washer on full-turn taps.

That means taps that you have to turn a few times for them to let the water out as fast as it will come.

If you have quarter-turn or half-turn taps, you will not be able to replace the washer as they don’t have washers, they have ceramic discs.

If you have full-turn bath taps, then you will need to remove the tap cartridges as above, and then replace the washer with the exact same washer.

These can be hard to find. I would recommend replacing the cartridges over replacing the washers.


Changing bath taps can be very difficult, especially on old bath taps and with copper pipes all the way up to the tap.

Bath taps can be very hard to access which is the main reason they are hard to replace. You might be better off replacing the cartridge if you only need to fix a dripping tap.

If you have easy access under the bath and you can reach the furthest pipe away easily, then you should be good.

Feel free to ask any me questions in the comment section below and I’ll try my best to help.

Please share this post if you find it helpful.


What size box spanner for bath taps?

The size box spanner needed for bath taps is 32 mm. This will cover almost all bath tap backnuts. You can buy a backnut box spanner with 32 mm at one end for bath tap backnuts, and 27 mm at the other end for bathroom sink tap backnuts.

How long does it take to change bath taps?

Changing bath taps can sometimes take half an hour, and other times take half a day. Every job and situation is different, but changing bath taps can be very awkward.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

    View all posts
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