How to Replace a Tap: Kitchen and Bathroom Guide
Step-by-step guidance for replacing a kitchen or bathroom tap in the UK, including tools, isolating the water, connectors and avoiding leaks.
Replacing a tap is one of the most achievable plumbing jobs for a confident DIYer. It takes patience more than skill, and the main enemy is a tight, corroded nut in a cramped space. If you plan properly and have the right tools, an hour or two is often enough.
Check the new tap fits
Before buying, check:
- Number of holes in your sink or basin: one for a mixer, two for separate taps.
- Hole diameter: most are standard, but measure.
- Thickness of the worktop or basin, as some fixings have limits.
- Water supply type: some modern taps need balanced pressures, which may not suit gravity-fed hot water. The instructions will say.
- Connection size: most use flexible tails with 15mm compression ends, but check.
If you need guidance on cost, our article on the cost to replace a tap lays out typical ranges.
Tools and materials
- Adjustable spanner and a basin wrench for awkward nuts
- Bucket and towels
- Torch
- New tap with flexible tails
- Plumber's PTFE tape, if the fittings are threaded
- Penetrating oil for stubborn nuts
- Possibly new isolation valves
Step by step
1. Isolate the water
Close the isolation valves beneath the sink. If none, shut the main stopcock; our guide to finding your stopcock explains how. Open the old tap to drain the lines.
2. Disconnect the old tap
Put a bucket underneath. Use the spanner to undo the nuts connecting the tails to the supply pipes. Water will drip, so expect that.
3. Remove the tap body
Unscrew the large backnut holding the tap to the sink. A basin wrench, a long-reach tool, makes this much easier in tight spaces. If it is stuck, apply penetrating oil and wait.
4. Clean the surface
Wipe away limescale and old sealant. A clean seat helps the new gasket seal.
5. Fit the new tap
Drop the tap into position, fit the washer and backnut underneath and tighten until firm. Check the tap is straight before the final tighten.
6. Connect the supply
Connect the flexible tails to the isolation valves. Hand-tighten, then a quarter turn with a spanner. The tails are flexible, so do not twist them tightly.
7. Test
Open the valves slowly and check for drips. Run the tap for a minute, and then inspect all joints with dry tissue.
Common problems
- Stuck nut: use penetrating oil, a basin wrench, or a nut splitter as a last resort.
- Tails too short: buy longer ones, or use extension fittings.
- Hole size mismatch: do not enlarge ceramic basins.
- Leaks at joints: undo, check the olive or washer seat, and refit.
When to leave it to a plumber
Hire one if you cannot isolate the water, if pipes need altering, if the sink may crack, or if you are fitting a boiling water or filtered tap that requires its own unit. If the old tap simply drips, try fixing it first. Compito can help you find a local provider if you would rather hand it over.
Worked example: an old bathroom basin pair to a mixer
A householder wants to replace two old pillar taps with a modern mixer. First they check the basin: it has two tap holes, and the mixer needs one. They choose a mixer with a base plate designed for two-hole basins, which suits the existing holes. They close the isolation valves, drain the lines, and then spend twenty minutes freeing a seized backnut with a basin wrench and penetrating oil. The new tap goes in, the flexible tails are connected and a dry tissue test finds no drips. Total time was about two hours, much of it spent on one stubborn nut.
Before you buy: a checklist
| Check | What to look for |
|---|---|
| Holes | One or two, and their spacing |
| Depth | Space under the basin or worktop for the nut |
| Pressure | Whether the tap suits your water system |
| Tails | Length and connection size |
| Finish | Matches existing fittings |
Common mistakes
- Buying a tap before measuring.
- Over-tightening the backnut on a ceramic basin.
- Forgetting to flush the pipes, so debris blocks the new aerator.
- Using sealant or tape on compression fittings when it is not needed.
- Not checking the new tap's instructions about pressure.
Special cases
- Rentals. Ask the landlord before changing fittings, and keep the old tap.
- Hard water. Soak seized nuts in descaler, and use a nut splitter as a last resort.
- Wall-mounted taps. Involve a plumber, as they need pipework behind the wall.
- Kitchens with a boiling-water tap. These need their own unit and electrical supply, so engage a qualified professional.
Finishing touches
Run the tap for a minute with the aerator removed to flush debris, then refit it. Wipe the finish with a soft cloth and keep the instructions and warranty details somewhere easy to find. For a drip after fitting, see fixing a dripping tap.
Frequently asked questions
Do I need to turn off the main water supply?
Not if you have working isolation valves under the sink. If not, you will need to turn off the main stopcock.
How long does it take to replace a tap?
A straightforward swap often takes one to two hours. Seized nuts and cramped cupboards add time.
Do I need PTFE tape on compression fittings?
Generally no. Compression joints seal with the olive. Tape is used on threaded joints.