How do I open my mixer tap and stop it leaking?

Turn off the water at the mains, first! If it is a dripping tap:
At the back of the handle there is usually a hole (sometimes plugged - just hoik the plug out) into which you have to put a small allen key. Loosening the allen screw inside will allow the handle to come off, and then you will have to put a spanner on the revealed nut to unscrew the top. Be very careful as you do this else you may displace the tap body on the sink. This will give access to the cartridge, which you will have to match on the internet (plenty of suppliers, just search carefully). These cartridges are not usually stocked by retail shops, sadly - too many types these days. When fitting the cartridge make sure that it cannot rock in the tap body. If this can happen pad the cartridge out with thin sheet plastic - pieces of plastic milk bottle work a treat. It must be central and not move.
If there is a leak in the tap body then one of the ring seals may have gone, and that usually means a new tap. Get a good one.

Laurie
January 2017