How to Fit Bath Taps | A Straightforward Step-By-Step Job

Fitting bath taps means shutting off the water, swapping the old units, and securing the new ones with washers and backnuts before reconnecting the supply.

Replacing bath taps is a job most competent DIYers can finish in a couple of hours. The process is the same for pillar taps, bath fillers, and most mixer sets. You’ll need an adjustable spanner, a basin wrench for awkward spaces, and some plumber’s tape. Before you start, check that your new taps suit the existing hole spacing — most bath tap sets use standard 180mm centers, but always measure yours first.

What You Need Before You Start

Having everything ready before you touch the water valve makes the job far smoother. Bath tap installation demands a few specific items:

• Adjustable spanner or tap spanner — for loosening and tightening nuts
• Basin wrench — essential for reaching awkward backnuts under the bath
• Plumber’s tape (PTFE tape) — for sealing threaded connections
• Bucket and towels — residual water will escape when you disconnect the old taps
• New tap washers and gaskets — most new taps include these in the box

The most overlooked prep step is isolating the water supply. Find the isolation valves on the pipes feeding the bath, or shut off the main stopcock if none exist. This is the one step that turns a simple job into a flood if skipped.

How to Fit Bath Taps: The Step Order That Works

Follow this sequence carefully. Each step is detailed enough for a first-timer, and every one matters for a leak-free result.

Step 1 — Shut off the water supply. Close the isolation valves on the hot and cold pipes, or shut off the main stopcock. Open the bath tap briefly to release any remaining pressure and drain the pipework.

Step 2 — Remove the old taps. Disconnect the supply pipes from the tap tails using your adjustable spanner. Loosen the backnuts underneath the bath with the basin wrench, then lift the old taps out from above. Clean the area around the holes thoroughly — old putty, sealant, or corrosion here will prevent a proper seal.

Step 3 — Position the new taps. Place the supplied rubber washer or gasket over the thread of each tap tail, then lower the tap into position through the bath hole. The washers sit between the tap body and the bath surface — they create the watertight seal and protect the bath finish from scratches.

Step 4 — Secure the taps underneath. From below the bath, slide the second washer (if supplied) and then the backnut onto the tap tail. Tighten the backnut with your basin wrench until snug. Do not overtighten — manufacturer guides consistently warn that excessive force here can crack the bath or distort the tap base. Snug is enough.

Step 5 — Connect the supply pipes. Wrap PTFE tape clockwise around the tap tails’ threads (usually two or three wraps) if the connection threads require it. Attach the hot supply to the hot inlet — marked with a red collar or the letter H, typically on the left — and the cold to the cold inlet. Tighten firmly with the spanner.

Step 6 — Turn the water back on and check for leaks. Open the isolation valves slowly. Inspect every joint — where the supply meets the tap tail and where the tap meets the bath — for drips. If you spot a leak, tighten the affected connection slightly and re-check. If you have a shower attachment, run it briefly to clear any trapped air.

Common Mistakes and Compatibility Issues

Fitting bath taps goes wrong in predictable ways. Knowing these failure points will save you a second trip to the hardware store.

• Overtightening the backnut. The most common error. It can crack the bath or strip the thread. Hand-tight plus a quarter turn is usually right.
• Clashing pipe sizes. If your new tap tails are a different size from the existing supply pipes, use an adapter rather than forcing a connection. Measure the thread sizes before you disconnect anything.
• Wrong hot/cold orientation. Hot goes on the left and cold on the right — this is consistent across fitting guides. Check the markings on the inlets before you connect.
• Skipping the flush. After reconnecting, run the taps fully open for a minute to flush any debris or swarf from the pipework before it lodges in the valve mechanism.

If the job feels beyond your comfort level — especially if your pipework needs rerouting or your bath is a delicate material like cast iron or stone — call a licensed plumber. Our roundup of the best bath taps can help you pick the right set before you start, but installation mistakes can cost more than the tap itself. When in doubt, professional help protects both your bath and your plumbing.

Also note that if you’re working near a hot-water heating system, some manufacturers recommend shutting that down too before you start. For wall-mounted mixer taps, the inlets use a 1/2-inch BSP female thread, and PTFE tape is standard on these connections. Incorrectly fitted temperature-control cartridges carry a scalding risk, so follow the included manual precisely for any thermostatic mixer.

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