How to replace basin taps

Video by Plumberparts. This walk-through is based on the video “HOW TO CHANGE OR REPLACE SINGLE BATHROOM BASIN TAP” from Plumberparts, which covers the whole process step by step — from isolating the supply to tightening the new tap and checking for drips. Worth a watch before you start; the section on using a basin wrench in a cramped pedestal cupboard is the most useful part.

1. Check the new taps will fit before removing the old ones

Most bathroom basins in UK homes have one or two tap holes of a standard size — typically 22 mm diameter. Pillar taps have separate hot and cold fittings through two holes; monobloc mixer taps use a single central hole with two flexible tails. Before you buy, measure the hole diameter and the distance between the holes if you have two. It is frustrating to discover mid-job that the new taps do not fit.

Also check the tap tail length against the thickness of your basin. Some ceramic pedestals are deep enough that a standard-length tap tail will not reach the supply pipes below without an extension. This is not a common issue, but it does catch people out. Most tap manufacturers list the tail length on the packaging.

2. Isolate the water supply

Look under the basin for the isolation valves — they are usually on the hot and cold pipes close to where they disappear into the floor or wall. Turn each one a quarter-turn with a flathead screwdriver so the slot is across the pipe rather than in line with it. That is the closed position.

If there are no isolation valves under the basin, turn off the main stopcock. Once the supply is off, open both taps fully to release pressure and drain the water from the pipes. Put a small bowl or folded towel under the basin waste trap while you work — there is usually a trickle of residual water when you undo the supply connections, and it always seems to find its way to the floor if you are not ready for it.

3. Disconnect the supply hoses and waste

Use an adjustable spanner to undo the compression nuts or push-fit connectors on the flexible supply hoses below the basin. Steady the hose with your free hand as you turn the spanner so the pipe above does not twist. Have your bowl ready as you break the seal — a small amount of water will come out even after you have opened the tap to drain the pipe.

You do not necessarily need to disconnect the basin waste pipe unless you are replacing the basin itself, but if you are working in a tight pedestal cupboard it can help to remove the waste bottle trap temporarily to give yourself more room. It unclips or unscrews at the base and drops straight off.

4. Remove the old taps

This is where the basin wrench earns its place. The back nut sits on the tap tail underneath the basin, usually in a space that is completely unreachable with a normal spanner. A basin wrench — sometimes called a tap spanner — has a long shaft and a swivelling jaw that grips the nut where nothing else will. Turn anti-clockwise to loosen.

On older taps the back nut can be heavily corroded or bonded with old limescale. Spray a little penetrating oil around the nut and leave it for 20 minutes before attempting it again. If it still will not shift, try gentle heat from a heat gun on a low setting — but be careful around the ceramic basin. Once the nut is off, the tap lifts straight out from above. Clean up any old sealant or limescale from the tap hole with a cloth and a little white vinegar before fitting the new tap.

5. Fit the new taps

Check whether the new taps come with a rubber gasket or a flat fibre washer for the base. If not, apply a thin rope of plumber’s silicone putty around the underside of the tap base before dropping it into the hole — this creates a waterproof seat and stops water tracking under the base and sitting on the ceramic. Do not use bathroom silicone here; it sets too hard to remove cleanly if you ever need to replace the tap again.

Drop the tap tail through the hole from above, ensuring the tap faces the right way. Underneath, slide the basin washer onto the tail, followed by the back nut. Hand-tighten first, then firm up with the basin wrench. Snug rather than hard — crushing the washer does not improve the seal. Wipe off any excess putty that has squeezed out around the base.

6. Reconnect the supply and test for leaks

Apply two or three wraps of PTFE tape clockwise around the tap tail thread before attaching the supply hoses. Connect hot to hot and cold to cold — worth double-checking as the pipes are sometimes labelled on the valves below but not always obviously so. Tighten the hose connectors firmly by hand and then give them a quarter-turn more with the spanner.

Open the isolation valves slowly and let the system fill. Check every connection immediately — supply hoses, the base of the tap, and the waste trap if you disconnected it. Run both taps for a minute to flush any debris from the pipes, then leave everything for five minutes and check again. A connection that looked dry can sometimes show a slow weep once the system has fully pressurised. If all is well, tidy up, replace any under-sink storage, and that is the job done.

When to call a handyman

Call Richard if the back nut is completely seized and will not shift without risking the basin, if the tap holes need enlarging for a different fitting size, or if there are no isolation valves and the stopcock itself needs attention first. Basin tap replacement is a common call-out around Sandwich and the villages — sometimes it is just quicker and less hassle to have someone come and do it, particularly in a small cloakroom where there is barely room to swing a basin wrench.