How to fit a bathroom sink

By Benjamin Clarke | Published on 17th December 2021

It's good to know how to install a sink in your bathroom regardless of whether it's a brand new basin or if you're replacing an old one. It's not the most complicated of tasks but it is important to get it right so that you know you've done it correctly so you have the confidence to actually use it. In this article, we'll give you an easy-to-follow guide that will take you step-by-step through the process of installing a basin in your bathroom.

Tools you'll need

In order to successfully install your bathroom sink, you'll find the job much easier if you have the tools below to hand:

Drill
Pliers
Screwdriver
Adjustable spanner
Sockets
Tape measure
Pencil
Spirit Level
Silicone caulking
Stanley knife
Old towel
Plastic tub/container

Replacing a sink

If you're replacing a sink in your bathroom with the same type of sink then this guide will help you do just that. If your new sink will not have a pedestal or will be wall mounted, you might need to get in a professional as the pipes might need re-routing or concealing.

Turn off the mains water supply
Use your pliers to disconnect the taps. Have your old towel ready to protect the floor from water.
Unscrew the nut that connects the drain to the sink and detach the drain.
Use your knife to scrape away any silicone caulking that is still connecting the sink to the wall.
Lift the sink away from the wall and clean up the wall to prepare for the new sink.

Measuring up

If your new sink is exactly the same size as your old one, then you can measure up your old one to see exactly where your new one will fi on the wall.

If fitting a new pedestal sink then measure the width and depth, then measure from the floor up to where you would like your new sink will be installed. The pedestal must be in the correct position to cover up your pipework, so keep this in mind when doing your measurements.

Likewise, if installing a semi-pedestal sink, work out how high your sink should be in order to ensure your pipes are concealed.

A new wall hung basin should be easy to measure up as you'll already have an idea of how it should replace the old one. Again, if swapping a pedestal sink for a wall-hung one, consider calling a plumber as that task is beyond the scope of this article.

Fitting a new sink

If you've removed the old sink, done your measuring, chosen your new sink and are happy with the location you want to install it, then please follow the process below. If you are unsure about anything, take the easy route and call in a professional to take over. It's usually not worth taking a risk where water is involved.

1. Turn off the mains water supply
Your water supply into your bathroom may have its own valve to isolate the water, but to be on the safe side, switch off your water at the mains water supply valve.

2. Mark up the wall
Put your sink against the wall in the place you would like it to be installed and gently draw around it with your pencil. You can then use your spirit level to ensure it's level and to find the central point. Draw a straight line up the wall (vertically) and across the floor. This should be done to the height and depth of your new basin.

3. Fit your taps
It's highly likely you will have bought new taps to go with your new sink, in which case, you'll probably have some instructions from the tap manufacturer explaining exactly how to fit them.

If not then you can read our guide on fitting a bathroom mixer tap to help you.

4. Fit the waste
Most modern sinks have an overflow so insert the plug into the hole ensuring that it matches up with the plughole and overflow cutout. The thread on the waste should have a bit of silicone sealant applied to it so that the washer can be put over for a nice tight fit. The nut should then be tightened onto the thread where you just applied the silicone and washer. Then connect the trap and the waste and make sure it's as tight as it can be.

5. Fit the sink to the wall
If installing a pedestal basin, then it will be easiest to take the stem and line that up against the wall where you marked it out with your pencil. Take the basin and place it on top of the stem and make sure that everything lines up with all the markings you made previously. This would be the time to make amendments if things don't look quite right, including making use of your spirit level to check your sink won't be lopsided. If you haven't already, mark out the holes in the sink where the bolts will go to attach it to the wall.

Once you're happy, remove the sink and stem from the wall and get the fixing kit that would have been provided with your sink. Take the drill and make some small pilot holes into the wall where the bolts will be inserted. Drill some bigger holes, fit them with rawlplugs and install the bolts with your spanner.

Take the stem of the sink and put the basin on top, ensuring you align the holes in the basin with your freshly-installed bolts. From your fixing kit, take the securing bolts and tighten them onto the bolts in the wall. Assuming you've done this correctly, the sink should now be fastened to the wall. You can give it a gentle tug to check it is indeed secrure and you can lay your spirit level on it to check it's straight.

6. Fit the water supply pipes
This bit is quite easy and simply requires you to connect the new taps to the pipes from your wall usually via the flexible tap connectors.

7. Turn mains water supply back on
Turn on the water and run the taps to check that nothing is loose or leaking. Tighten up again if necessary.

8. Seal the sink
Take your silicone sealant and gently squeeze it out in a neat line where the basin comes into contact with the wall. This will help further secure the sink to the wall as well as providing a waterproof seal the the tiny gap.

Stand back and admire your work.

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