How To Change A Tap Cartridge
How To Change A Tap Cartridge
A tap cartridge is the internal valve that controls your water flow, temperature mixing and assists with turning your tap on and off. Most modern taps usually use ceramic disc cartridges, which can wear out over time due to limescale, debris or general wear.
Replacing a tap cartridge (also known as tap valves or glands) is an effective way of fixing dripping taps, inconsistent water flow or stiff handles. In this guide we’ll walk you through the tools needed, removal steps and installation techniques you need to do the job.
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Key takeaways
Difficulty: A straightforward DIY project that typically takes 15–30 minutes.
Essential step: Always isolate the water supply at the mains or via the isolation valve before starting to prevent flooding.
Precision matters: Cartridges are not universal. You must ensure a like-for-like replacement by matching the diameter, length, and "spline count" (the teeth at the top) of your old unit.
Top tip: Use a penetrating oil if the retaining nut is seized due to limescale, and avoid overtightening during reassembly.
Essential tools for changing a tap cartridge
Below is a list of tools you might potentially need to change your tap cartridge.
- Adjustable spanner (or wrench)
- Screwdriver (flathead or Phillips)
- Allen key (if required)
- Replacement cartridge (correct size and type)
- Cloth or towel
- Optional: penetrating oil
How to replace a tap cartridge: Step-by-step guide
Outlined below, is a step-by-step guide on how to change a tap cartridge. For beginners this could take between 30-60 minutes, but for more avid DIYers this should take between 15-30 minutes depending upon experience.
Step 1. Turn off your water supply
This is the most critical part of the process and needs to be done before dismantling your tap. First, you need to locate your isolation valves under the sink (these are usually small valves attached to the hot and cold water pipes). Once located, you need to turn them clockwise to shut off the water. When closed, you can open the tap to release any remaining pressure (and water).
If your sink does not have isolation valves, then you will need to turn off the main water supply before proceeding.
Step 2. Remove tap handles
In order to access the cartridge beneath, you will need to remove your tap handles. The method you use, depends on the type of tap handles you have.
Lever taps: locate the grub screw (that secures the handle in place), and carefully loosen using an allen key. You don’t usually have to remove the screw completely, just enough for the handle to move free. Gently lift the handle upward to remove - but avoid forcing it, as it can damage the cartridge stem underneath.
Hot & cold taps: on dual-handle taps, look for the cap on top of the handle (normally marked with a red or blue indicator - for hot and cold), and carefully pry the cap off using a flathead screwdriver. Underneath, you’ll find a fixing screw which needs to be unscrewed fully and then lift the handle straight off the spindle - avoid using excessive pressure as this could cause damage.
In some cases it may be difficult to remove the tap handles due to mineral buildup or corrosion. If this is the case, you could try applying a small amount of penetrating oil (such as WD-40) around the base to loosen it. After about 10 minutes, you can try removal again.
Step 3. Remove retaining nut
Once the handles have been successfully removed, you’ll see the retaining nut that secures the cartridge. It’s essential that the removal of this is done very carefully as it holds the cartridge firmly in place.
Many modern taps include a chrome sleeve that you can unscrew by hand. If this is the case, then carefully turn it counter-clockwise to remove it. If it is hard to turn, try gripping it with a cloth (instead of tools), as this could damage the finish.
After this, secure your adjustable spanner around the retaining nut and turn counter-clockwise to loosen. If it is hard to turn, you can use a small amount of penetrating oil (around the threads) and try again.
Once the nut has been removed, ensure a safe place to keep it (along with any washers or spacers), and you should then have clear access to the cartridge
Step 4. Remove the cartridge
Start by gripping the top of the cartridge firmly and pull upwards - you may need to gently wiggle from side to side. In most cases, you should be able to do this by hand (with moderate pressure), but try to avoid excessive twisting as this can cause damage.
If you cannot remove it by hand, there are tools available to help (such as a cartridge puller tool) - but make sure you carefully read the manufacturer's instructions to avoid cracking the housing.
Once the cartridge has been removed, you should clean the inside of the tap body using a cloth to wipe away any debris and remove any limescale if necessary. Also you should ensure that the new cartridge is an exact match before trying to install it.
Step 5. Install the new cartridge
When installing the new cartridge, it’s essential that this is done with absolute precision and care to ensure a watertight seal and proper temperature control. If the cartridge is even slightly misaligned this can result in leaks, stiff handles or affect your hot and cold water flow.
Start by applying a small amount of plumber’s grease (avoiding petroleum-based product) to the rubber o-rings on the new cartridge, as this will help create a better seal and makes future removal easier.
Carefully align the locator holes (or notches) before inserting the cartridge. It should sit flush and drop fully into place without forcing it. If it doesn’t sit properly initially, then remove it and check the alignment again.
Once the cartridge is fully seated you can reinstall the retaining nut by hand - turn it clockwise until it fits snug. Use an adjustable spanner to secure it firmly but do not overtighten it.
Before refitting the handle, you should check that the cartridge is sitting level and flush, the o-rings aren’t visible and the retaining nut is secure. You should ensure proper installation at this stage to avoid long-term issues.
Step 6. Reassemble tap
Once the new cartridge has been installed, you can now reassemble the tap. It’s important that you take care when doing this, to ensure proper alignment, and to achieve a professional finish.
By hand, start refitting any decorative shrouds or sleeves that were removed in the initial steps. Next, align the tap handles onto the cartridge stem and push into place. If fitted incorrectly, the tap won’t shut off properly.
For lever taps you need to tighten the grub screw back on using your allen key. For dual taps, slot the screw through the top of the handle and tighten with a screwdriver.
Once the tap has been fully assembled, you should do some simple checks before restoring the water supply. Move the tap handle gently to check it operates correctly. If there is any stiffness or feels too tight, the retaining nut may be slightly overtightened and may need adjusting. Make sure you are completely happy with the alignment and everything looks sound. Finally, wipe down the tap to remove any grease or debris for a neat, finished appearance.
Step 7. Test the tap
When you are happy that the tap is reassembled properly, you can now restore the water supply and carefully test.
Begin by slowly reopening the isolation valves under the sink by turning them counter-clockwise to allow water flow. Ensure you twist them gradually rather than fully, as this will prevent a sudden surge of water. If you turned the mains water supply off, then restore it slowly at the mains valve.
Keep the tap in the off position once supply is back on and inspect the area before turning the tap on. Check for any drips around the retaining nut and base of the tap. If everything looks dry you can turn the tap on slowly.
When the tap is on, you should check:
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The handle is operating smoothly, allowing full motion.
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The hot and cold controls should operate correctly.
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Ensure water flow is steady.
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Check it’s not dripping (look under the sink too for slow leaks).
Once everything is functioning properly and there are no visible signs of leaks, your tap should now operate efficiently and you’ve successfully changed your tap cartridge. Take the time to dry all surrounding areas to make it easier to spot any slow leaks later - you could even leave a piece of tissue to detect any drips throughout the day.
It’s a good idea to check again over the next few days to ensure everything remains watertight and operational.
If you are experiencing problems after the installation, then you can always call a professional out to help.
Common installation mistakes to avoid
When changing a tap cartridge it’s important to ensure you follow the process correctly and always fix any small errors along the way to avoid causing long-term damage. Below are some common mistakes, and how to avoid them.
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Not turning the water off - this is one of the biggest mistakes that can happen in the process. Always ensure the water has been shut off correctly before attempting any work. If you are unsure, you can shut off the main water supply completely.
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Using the wrong cartridge - as they are not universal, you should always confirm it’s a like-for-like replacement before trying to install. Even if they look similar, there could be small differences in height or alignment pins. If you install the incorrect cartridge, it can cause leaks or improper operation, so you should avoid this by double-checking the cartridge before installing. If in doubt, you can always check with a plumber beforehand.
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Overtightening - when fixing your retaining nut, you should secure firmly but not too tight. If you overtighten it can crack the cartridge housing, cause stiff handle movement and distort the o-rings.
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Using excessive force - when trying to install your tap cartridge, make sure you apply steady pressure only, and take your time. If too much force is used, you could damage the components which could be costly.
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Misalignment - when installing, you should always ensure the locator pins must line up with the corresponding slots inside the tap body. If even slightly out, it can cause your tap to leak or the flow may be restricted.
If the installation process doesn’t go to plan, you should contact a professional to help.
Key considerations
Replacing a tap cartridge can be a straightforward task, but accuracy and precision is a vital part when installing. The most important part is ensuring that your tap cartridge replacement is an exact match, as installing a different one could lead to leaks, restricted flow or affect the hot and cold operation.
The quality of your water also plays a key role in your cartridge longevity, particularly in hard water areas where limescale buildup is common. It’s important to clean the housing before installation to extend the life of the cartridge.
It’s also worth considering calling in a professional if you don’t feel confident in replacing your cartridge. Although you will face the initial costs, you will have peace of mind that the component has been installed correctly.