How to Install a Mixer Tap and Waste

Upgrading your bathroom sink with a new mixer tap and waste is one of the easiest ways to refresh your space. This straightforward DIY project can be done in under an hour with just a few basic tools.

This guide will walk you through every step—from installing the tap and waste to troubleshooting leaks and ensuring a secure, leak-free fit. Watch the video below, then follow the detailed instructions to get your new basin mixer tap up and running.

Watch: How to Install a Basin Mixer Tap & Waste

What You'll Need

Before starting, make sure you have all the necessary parts and tools for the job:

• New mixer tap – Includes threaded bar, tap tails, and sealing washer.
• New pop-up waste – Includes rubber washers, backnut, and plug mechanism.
• Basin wrench (tap spanner) – Essential for tightening nuts in tight spaces.
• Adjustable wrench or pliers – Used for water supply lines and securing fittings.
• Bucket & towels – To catch any water when disconnecting pipes.
• Plumber’s tape (PTFE tape) – Helps create a watertight seal on threads.
• Screwdriver – Required for some tap installations.
• Silicone sealant (optional) – Extra protection against leaks for the waste.

Fitting a Basin Mixer Tap & Pop-Up Waste: A Step-by-Step Guide

Step 1: Remove the Old Tap and Waste

Shut Off the Water Supply

• Locate the isolation valves under the basin and turn them clockwise to shut off the water.
• If your setup doesn’t have isolation valves, turn off the main water supply.

Pro Tip: Open the existing tap to drain any remaining water and place a bucket under the pipes to catch any drips.

Disconnect the Old Tap

• Use a basin wrench or spanner to loosen the nuts securing the old tap under the basin.
• Disconnect the tap tails from the water supply pipes using an adjustable wrench.
• Carefully lift the old tap out from the top of the basin.

Remove the Old Waste

• Place a bucket under the waste trap to catch any water.
• Unscrew the waste trap and set it aside.
• Use a wrench or pliers to loosen and remove the backnut securing the old waste to the basin.
• Push the old waste up and out from the top of the sink.
• Clean the drain hole thoroughly—scrape off any old sealant or residue before installing the new waste.

Step 2: Install the Mixer Tap

Check Your Parts

• Ensure you have all the components needed to assemble the mixer tap.
• Identify the threaded bar, tap tails, rubber seal, and mounting washers.

Attach the Threaded Bar

• Screw in the threaded bar at the base of the tap by hand or with a screwdriver.
•  Avoid using pliers or grips as they could damage the thread.

Attach the Tap Tails

• Screw in the tap tails by hand—these are the flexible hoses that connect to the water supply.
• Do not overtighten, as this could strip the threads or cause leaks.

Position the Tap on the Basin

• Ensure the rubber seal is in place—this seals the tap to the basin.
• Thread the tap tails through the hole in the basin, making sure the tap sits flat and straight on top.

Secure the Tap Under the Basin

• Underneath the basin, install the rubber clamp washer (it should have gaps for the tap tails).
• Place the metal clamp washer over the rubber washer.
• Screw on the brass nut by hand to hold everything in place.
• Adjust the tap’s position from above to ensure it’s straight.
• Tighten the brass nut using a spanner.
• Use only the supplied spanner to avoid damaging the tap tails.

Step 3: Install the Pop-Up Waste

Prepare the Waste Components

• Place one of the rubber washers over the waste—this sits on top of the basin to create a watertight seal.

Insert the Waste into the Basin

• Push the waste through the waste hole, ensuring the rubber washer sits flush to the basin.

Secure the Waste from Below

• Underneath the basin, place the second rubber washer over the waste thread.
• Screw on the backnut by hand to hold the waste in place.

Tighten the Waste Nut

• Use a spanner to tighten the nut, but do not overtighten, as this could damage the basin or cause leaks.

Step 4: Reconnect the Plumbing

Reconnect the Water Supply Lines

• Attach the flexible tap tails to the hot and cold supply pipes.
• Hand-tighten, then use a wrench to gently secure the connections.
• Avoid over tightening—this can damage washers and create leaks.

Reconnect the Waste Trap

• Secure the U-bend trap back onto the waste outlet.
• Hand-tighten the trap fittings, then give a slight turn with pliers to ensure a snug fit.

Step 5: Test for Leaks

• Turn the water supply back on and check all connections for leaks.
• Run the tap and inspect the base of the tap, supply connections, and waste trap.
• Test the pop-up waste by filling the basin and letting the water drain.

Troubleshooting Your Basin Mixer Tap & Waste

Even the best DIY jobs can hit a snag. If your new basin mixer tap or pop-up waste is leaking, loose, or not working quite right, don’t panic—we’ve got the fixes for the most common installation issues.

• If you spot leaks, try tightening the fittings slightly or adding PTFE tape to the threads.
• If water drips from the waste area, re-tighten the backnut or apply a small amount of silicone sealant under the flange.

Common Issues

Water leaking around the waste?

Apply silicone sealant under the waste flange and re-tighten.

Dripping from the tap tails?

Check the rubber washers inside the connections—replace if necessary.

Tap feels loose?

Tighten the backnut under the basin with a basin wrench.

 Water drains slowly?

Ensure the trap is installed correctly and isn’t clogged with debris.

Bonus Tips for a Leak-Free Install

• Use PTFE tape on all threaded connections to prevent drips.
• Hand-tighten connections first, then give a slight turn with a wrench.
• Clean your aerator every few months to maintain strong water flow.
• Avoid harsh cleaners on taps—mild soap and a soft cloth work best.

A Simple Upgrade with Big Impact

With just a bit of patience and the right tools, you've successfully installed your new mixer tap and waste—no plumber required!

Want to level up your DIY skills? Check out our other step-by-step guides, bathroom design inspiration, and expert buying guides. And if you found this useful, share it with a fellow DIY enthusiast!

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