How do I fix a leaking tap? Taps can leak for any number of reasons and I would just like to clarify that if you are not sure where the leak originates and confident that you can perform this repair yourself, it is best to call a qualified plumber instead of attempting this on your own.
The first step is to isolate the water supply from the mains (water meter, tap out the front of your property) before removing any fittings. Once this has been done, check that the water flow has been sufficiently isolated by opening the taps and allowing any excess water to release itself. There should be a slow flow and become a trickle.
Now open the tap to the fully open position and remove the tap handle button screw using a small adjustable spanner (usually a button with the hot/cold symbol on it) to remove the tap handle, keep in mind that not all tap assemblies are the same. If you live in an area with hard water, the tap handles and fittings may be stuck on due to calcium build-up and may need to be removed using some form of mechanical aid, but you should be able to remove the tap shroud without having to remove the tap handle. The tap shroud is the cover that surrounds the tap body and is removed by hand or using a cloth and a wrench so as not to scratch the surface.
Using a tap spanner kit (socket that fits over the entire tap body) or large adjustable spanner, loosen the spindle assembly and unscrew from the body (standard taps require a 22mm spanner to undo the spindle assembly from the body). Remove the tap valve (plastic/ brass plug under the spindle) and using a torch, inspect the area underneath. This is called the tap ‘seat’ and is generally made of brass. The seat needs to be clean and flat for a new tap valve to work efficiently and last longer than a few months, so usually this will require a reseating tool to clean it up.
A reseating tool can come in drill driven or hand tap styles and both will do the trick although most people will have a preference. The key is to place the tool against the seat slowly and with minimal pressure and allow the tool to lightly scrape the surface just enough to remove the dirt and indentations. It is best to take off little bits at a time and inspect in-between so you do not damage the seat. The seat can be damaged by uneven force and angle of the tool, so be careful. However, if you damage the seat, it is possible to buy a reseating kit that can thread a new seat into your existing tap body, so don’t panic too much…
Now the seat should look shiny and even across the surface, if it does not then you may need to use the reseating tool again. Now clean as much of the metal filings out as you can, bearing in mind that if you leave the tap open when turning the mains back on this will help to clear the lines (it is a good idea to remove the aerator from the spout to allow any filings to come out and give it a good clean).
Now check the spindle by winding it up and down with the tap handle. If the thread is stiff, you can clean the entire assembly in CLR and boiling water to remove any excess calcium or dirt. The spindle has a large red body washer and normally two black O-rings that should be replaced. Give the spindle thread and O-rings a ‘light’ greasing using the appropriate plumbing grease (just a little is fine). This helps to protect the O-rings from splitting and keep the tap turning smoothly. Now screw the spindle back into the thread and replace the tap valve/ washer, I use the Fix-A-Tap 13mm brass valves as they form a good seal and open easily. There are many tap valves on the market and it is important to choose a good quality valve because this is the main reason that taps leak, so choosing cheap alternatives will inevitably lead to future repairs and by future, I mean sooner rather than later!
Place the tap valve inside the spindle and insert the assembly back into the tap body and tighten. Now replace the tap handle on loosely and turn towards closed, but not fully (when turning the mains back on the water will remove any filings instead of them becoming stuck under the valve) and turn the mains back on. Leave the water to flow for a minute or so to clean the pipe out before turning off and replacing the aerator into the spout. Now replace the shroud, tap handle and button screw.
The tap should open easily and shut easily with minimal pressure required to close the tap. If you have followed all these steps and are still experiencing a leak, you may require a licensed tradesperson to diagnose the problem. If you have followed these steps and the tap turns easily, closes easily and is not leaking then congratulations, you have successfully fixed your leaking tap.