A leaking tap is a nuisance; it wastes water, looks unsightly and the continuous dripping can be an annoying sound. Fortunately, it is usually one of the easiest and cheapest things to fix. The problem is almost always the washer or in the case of single level mixer taps, the cartridge.
Before starting, make sure the water supply to the tap is off. This can be done through your home’s main water supply shutoff valve or in some kitchens and bathrooms an isolator which is fitted where the flexible pipe to the tap is joined to the piping in the wall.
If the tap is shrouded by a cover, unscrew this first with a wrench or by hand. Next remove the tap handle, this is attached by a screw underneath the handle or in some cases by a screw under the hot or cold symbol. Now take the screw in part of the tap out, this is best done with a wrench fitted around the tap body. Use newspaper, a cloth or some masking tape on the tap surface to prevent the wrench from scratching the chrome finish. Once the tap has been taken apart, you should see a number of rubber seals and o-rings. Take any worn ones off and then go to your local hardware or plumbing store and find exact replacements. Refit the new seals and o-rings and then reverse the process to put the tap back together again.
In the case of a mixer type tape, when the tap is taken apart, a cartridge should come out underneath the mixer head. If there is just dirt or scale in the cartridge then it is sometimes possible to clean out however it usually requires replacement. Find a replacement at your local plumbing store, they may have to order it from the tap manufacturer.
Finally turn the fixed tap to the off position and then turn the main supply back on. If the tap is still leaking then it may require re-seating in the area where the washer sits. This is best done by a plumber but most hardware stores stock re-seating kits with instructions on the packaging on how to do the repair.