How to connect a new bath tap: step-by-step DIY guide

A new bath-shower tap instantly gives your bathroom a fresher look and makes bathing and showering more pleasant again. If the tap is a surface-mounted (exposed) tap on existing wall connections, you can often replace it yourself with good preparation. In this DIY guide you will read step by step how to connect a new exposed bath-shower tap: from shutting off the water and setting the S-unions to the leak test and sealing.

⚠️ Please note: this guide is about an exposed tap on existing wall connections. Is it a concealed (built-in) tap, do pipes need to be moved, or are you unsure about the condition of the pipes in the wall? Then leave the work to a certified installer. Never work on gas or electrics in the bathroom yourself. A professional makes sure everything is safe and leak-free.

Replacing a shower tap without a bath spout? Then read our step-by-step guide how to connect a new shower tap.

What do you need to connect a bath tap?

Which materials do you need?

• An exposed bath-shower tap for wall mounting, for example the Cari bath-shower tap, the Elio bath-shower tap, the Mille bath-shower tap or the Cersania bath-shower tap. Would you prefer a constant water temperature? Then an exposed thermostatic tap such as the Virgo thermostatic bath-shower mixer is an option. Choose a tap that suits your bathroom and your connections.
• The S-unions, cover plates (escutcheons) and sealing washers (often with a filter) that belong to the tap. Check the manual to see what is included.
• Thread sealant suitable for drinking water, such as PTFE tape or sealing thread. Follow the manual of the tap or the union.
• A metal shower hose if you are replacing the hand shower hose as well.
• Sanitary silicone sealant and a sealant gun to finish the opening around the connections watertight.
• Blue masking tape to mark the position of the unions and protect the tiles.

Which tools do you need?

• An adjustable wrench and a combination wrench set for the union nuts and the S-unions.
• A water pump pliers set and, if needed, a pipe wrench to loosen old, stuck unions. Always put a cloth between the pliers and the chrome.
• A spirit level, a tape measure and a pencil or marker.
• A bucket, dry cloths and a torch.

Which protective equipment do you need?

Wear nitrile-coated work gloves, safety glasses and knee pads when you kneel next to the bath. Safety shoes and sturdy work trousers make the job safer. Choose your own size.

How do you prepare for the installation?

Shut off the water at the main stopcock or with the bathroom shut-off valves. Not sure which valve belongs to the bathroom? Then read our blog about shut-off valves and ball valves. Then open a tap at a lower point, so the pressure is released and the remaining water can drain.

Measure the centre distance: the distance between the centre of the hot and the cold water connection. For exposed bath-shower taps, 150 mm is common. S-unions can compensate for a small deviation; the manual of your tap states which range is allowed. Hot is usually on the left and cold on the right. Check this, especially with a thermostatic tap.

Take a photo of the old situation and read the installation manual of the new tap. For many taps, you will find it as a download on the product page. Put a thick cloth in the bath to prevent scratches and put the plug in the drain, so no small parts disappear.

Is the wall plate loose, does the connection turn along, do you see rust or a leak in the wall, or is it a tap on the bath rim? Then different steps apply. In those cases, call in an installer. A professional immediately sees what is needed behind the tiles.

How do you connect a new bath tap, step by step?

1. Depressurise the pipes. Check that the water is really off: open the old bath tap on hot and cold. After the remaining water, nothing more should come out. Place a bucket under the tap.
2. Remove the old tap. Loosen the union nuts with the wrench and catch the remaining water. Remove the cover plates and carefully cut away old sealant around the unions. Then unscrew the old S-unions from the wall plate. If a union is stuck, use the pipe wrench with care. Does the wall plate turn along? Then stop and call in an installer.
3. Clean and flush. Remove old tape, sealant residue and limescale from the thread in the wall. Then flush the pipes briefly: turn the water on for a moment with a bucket and a cloth at the connections, preferably with two people. This keeps dirt out of the filters of the new tap.
4. Set the S-unions. First screw the new S-unions into the wall plate without sealant. Set them so they protrude equally far from the wall, are at the correct centre distance and are perfectly level. Check this with the spirit level and the tape measure. Never use great force: unions can crack.
5. Mark and seal. Use a marker to draw a line on a piece of masking tape on the tile and on the union. Unscrew the unions and count the turns. Wrap PTFE tape around the thread in the direction of screwing (or use sealing thread according to the manual). Then screw them back in exactly as far, up to your mark.
6. Fit the tap and test for leaks. Place the supplied sealing washers or filters in the union nuts, as the manual describes. First screw the tap onto the unions by hand, then tighten with the wrench, with a cloth in between. Tight is tight: overtightening damages the washers. Turn the water on slowly, let hot and cold run briefly to remove air from the pipes and check every connection with a dry cloth.

7. Seal and fit the cover plates. Does everything stay dry? Shut off the water again and remove the tap one more time. Seal the opening around the wall plate and the S-unions with sanitary silicone sealant, so no water can get behind the tiles. Screw the cover plates over the unions against the wall.
8. Fit the tap for good. Check that the sealing washers are still seated in the union nuts. Tighten the tap again evenly and check with the spirit level that it is straight. Then connect the shower hose and the hand shower, with the matching washers.
9. Do the final check. Turn on the water and test the bath spout, the diverter to the hand shower, and hot and cold. With a thermostatic tap, set the temperature according to the manual. Check all connections for drips again after a few hours and the next day. Let the sealant cure according to the packaging.

Which mistakes do DIYers often make?

• S-unions not level or not protruding equally far. The tap then hangs crooked and the risk of leaks is high.
• Overtightening. This damages the sealing washers, the thread or even the union.
• Sealant in the wrong place. PTFE tape belongs on the thread in the wall; the union nuts seal with the supplied washers.
• Hot and cold swapped. Especially with a thermostatic tap, the temperature control will not work properly.
• Not flushing the pipes. Dirt and grit then clog the filters of the new tap.
• Sealing before the leak test. Always test first that everything stays dry.

💡 Tip: put a paper tissue under every connection when you turn the water back on. You will spot a small wet patch much faster on the tissue than on the tiles.

How do you work safely when replacing a bath tap?

You are working in a wet room, often bent over or kneeling, with sharp threads and old sealant residue. That is why you wear nitrile-coated gloves for grip and protection, and safety glasses when you loosen corroded unions or cut away sealant. Knee pads protect your knees on the hard bathroom floor.

Safety shoes protect your feet if a tool falls, and work trousers keep you dry and protected. Keep the floor dry, do not stand in the bath with shoes on and make sure you have good light. Is there a socket or lighting nearby? Keep it dry and always leave electrical work to a qualified installer. You will find all personal protective equipment in our workwear and PPE category. Read more tips in our guide safe working on the construction site.

What do DIYers often ask about connecting a bath tap?

Can I replace a bath tap myself?

An exposed tap on existing wall connections usually yes, if you work calmly and accurately. For a concealed tap, a tap on the bath rim or when pipes need to be moved, call in a certified installer.

What is the centre distance of a bath tap?

For exposed bath-shower taps, 150 mm is common. Always measure it yourself. S-unions compensate for a small deviation; the manual of the tap states which range is possible.

Can I reuse my old S-unions?

Preferably use the unions and seals that belong to the new tap. Always replace old unions with limescale, rust or damaged thread.

The tap leaks at the union nut. What now?

Shut off the water and check that the sealing washer or filter is seated correctly and that the unions are straight. Then tighten evenly, no harder than necessary. Does it keep leaking, or does it leak inside the wall? Then call in a professional.

Should I choose a mechanical or a thermostatic tap?

A single-lever mixer, such as the Cari or Elio, is operated with one lever. A thermostatic tap keeps the set temperature constant. Not sure? Contact us for advice.

Are spare parts available later?

For a number of taps, yes. For example, there is an aerator for Cari and Elio, among others, and for Luvio taps a separate lever handle and a tap head part with ring. After the job, you may want to reseal the bath edge; read our blog how to reseal your bathroom with new silicone.

Where can you find everything for your new bath tap?

At Saniso, the online DIY store for building and renovating, you will find bath-shower taps, accessories, tools and protective equipment for this job.

• Take a look at the Mille, the Cersania and the Virgo thermostatic bath-shower mixer.
• Find the right construction tools and workwear and PPE.
• Create a customer account and order easily.
• Working on a larger project? Request a project quote.
• Book a showroom visit in Zwaag, at least 24 hours in advance.
• Not sure which tap suits your bathroom? Contact us.

Build your home with Saniso.