How do I change a tap without draining the whole house?

Angle valves under the basin are what turn a tap change into a local job. With them, the water is off in two turns of a screwdriver; without them, the main comes off and the building is dry.

What the valves do

Each supply — hot and cold — passes through a small valve at the wall before it reaches the tap. Closing them isolates the basin and nothing else. They also make everything downstream serviceable: the tap, the hoses, a filter, a bidet seat.

Where the job actually is

Getting a spanner onto the back nut under the basin, which is why a basin wrench exists and why there is no real substitute for it. The rest is undoing two flexible hoses and lifting the tap out.

Two things worth doing at the same time

Fitting double-outlet valves, if a bidet seat or a filter tap might follow. And replacing the flexible hoses, which are cheap, are a consumable, and are the part that fails messily.

What decides whether it goes well

Measuring before ordering: tap hole diameter, tail length to the valves, and worktop thickness. Everything else is spanner work.

This does not replace the manufacturer's own instructions. Every dimension, thread size, flow rate, operating pressure, water seal depth and load figure on this page is reported from the manufacturer's own documentation, with its unit written as published, and named as such — none of it is measured here. A flow rate is reported with the pressure the manufacturer measured it at, and is never converted to another pressure, because no conversion exists.