How to change a tap valve

Tips when changing a tap valve

Index > Tap Spares > Tips and hints for changing a tap valve

Also see...

Measuring and specifying a Tap Valve


Changing a Tap Valve

A few of these tips might seem obvious when mentioned, but it is surprising how easy it is to forget when doing battle with a stubborn tap.

Above all else, remember you are trying to fix a leaky tap. In doing so you don't want to incur more expense by causing additional damage to the tap, the sink or the associated plumbing. Take a good look at the job before you start and above all else... take your time!


In a perfect world, you will expose the valve in the tap body, unscrew it and replace with a new valve. However, the world is rarely perfect! The valve you are trying to replace will probably have been in situ for a considerable time and is likely to be seized in with a build-up of lime scale and grime for good measure. For this reason it is probable you will need to use a degree of force to achieve your objective. This is where unintentional damage can occur.



First things first. ISOLATE YOUR WATER SUPPLY. If you don't turn off your supply to the tap you may have quite a flood to deal with. Remember, the part you are about to remove is holding back the water supply. If you are fortunate enough to have inline service valves (illustrated right) then a simple quarter turn on the screwdriver slot will do the job (when the slot is in line with the pipe the valve is open). If you don't have service valves you will need to isolate supplies by other means (stop cocks, etc.) If you are working on the hot tap on a gravity system this might involve draining down the header tank in the loft.


Good advice: If you don't have inline service valves now is a good time to put some in. They only cost a few pence and have compression fittings, making them easy to fit. Once there, you'll find routine maintenance easy in the future.


Taps are both functional and decorative. Somebody will have spent time and money creating an aesthetically pleasing look. You really don't want to go and damage the tap body and it's shiny finish in your haste or frustration to change the internals. Always protect the surface finish of the tap. This can be done in a number or ways...  masking tape, rags, tissues etc - whatever is appropriate to the forces you might need to exert on the item.


When you begin pulling your tap about remember it is connected to a pipe. If you dislodge the tap from it's normal position it is possible you will have twisted it in the connection to its supply. This can damage or weaken connection and occasion a leak. You may of course have flexible hoses between pipe and tap, but still be cautious about damaging the sink.


There are countless tap designs. The internals can be hidden from view by various means - covers and shrouds often unscrew to reveal the valve (usually made of brass). There are way too many variations to list so examine your tap and use your imagination. Taps can be individual or combined to form a mixer (two taps/one spout). With the latter, some will have hot and cold knobs or levers, others may have a single level with multiple function (lift for flow/left or right for temp). Exposing the internals (the valve itself) can be half the trick (remember covers can also become stuck and gummed up). We shall assume you have found the right way and can now proceed.


The brass valve you need to remove might unscrew without much drama - if you're lucky! More often, you'll find the item has been in situ for years and will need a bit of encouragement (also referred to as 'brute force'). This is where you must be careful not to cause damage elsewhere. Grips used to hold the tap body while you tug on the spanner trying to free the valve can ruin the finish or damage threads. The force required to loosen the valve may twist the tap out of position causing issues with joints or damage to the sink. If you can get the valve out then you are 9/10ths there and fitting a new unit will only take you a few moments more. If you can't, then 'other means' might be appropriate.


It doesn't hurt to try freeing a stuck valve body with a little lubricant or penetrating fluid (such as WD40 or such like). If you seem to have come up against an immoveable object you might need to tackle the job differently. Sometimes, to avoid causing damage to everything else, it pays to remove the tap or mixer from the sink entirely and perform your repairs out of situ. This might sound daunting, but in reality a tap is quite easy to remove and refit - simply undoing the water connection with a spanner and undoing the nut/s holding the tap still. Doing so can make this job so much easier and help avoid collateral damage.


Always remain mindful of damaging the finish on your tap or parts that are threaded. Even if you remove the tap from the sink you still have to grip it, so let's not spoil things now.


There is always the possibility that you cannot budge the valve no matter what you try - unlikely, but possible. Then of course, you might remove the valve body and find that there is physical damage to the valve seat within the casting of the tap body (inspect for small divot/s in surface of the seat). Unless you can re-cut the seat (tap re-seating tools are available for purchase or hire) then I'm afraid the tap becomes a write-off. Unfortunately you won't know until the valve is removed.


It is for this reason that a manual inspection of the valve is a worthwhile exercise. Not only can you properly identify the valve you need as a replacement, you also get to inspect the condition of the valve seat. Disappointing as discovering a write-off may be, look on the bright side - you have saved wasting any more time and money on repair and your old tap is off an out of the way ready for a new one to be fitted in its place.


Reinstating your sink and taps to former glory is a matter of going backward through whichever steps have proved necessary during repair. Continue to protect shiny surfaces from damage as you tighten nuts. If a taps has been substantially loosened or removed it is often a good idea to apply a little silicone between the tap body and the sink to act as a gasket - padding the two surfaces with a leak-proof seal. Connect your supply pipe if it has been removed making sure you fit the sealing washer. Tighten, but don't over-tighten. Open your service valve slowly reintroducing water and inspect for weeps or leaks.


All being well you are back in business.


a) Always use proper tools. Don't try using grips where a spanner is required. Tools were designed for a purpose. Don't be a bodge-artist.

b) Inspect your valve and valve seat. If you are happy that the valve seat is in serviceable condition compare your valve to those we offer as a suitable replacement and get your order underway.

c) Advice given here can only be in general terms and is provided to help you. Whether you choose to use advice or not, no liability will be accepted for consequences that may arise. Never undertake a job unless you feel able and competent. Always turn off your water supply.

d) There will always be exceptions. We apologise if details here do not match your installation exactly. Please treat any advice in the spirit has been given - to be helpful!


At the end of the day you are always welcome to call for advise. Click here for further information and to visit the website.


Also see... Measuring and specifying a Tap Valve


Tap valves and cartidges for bath and basin taps and mixers