Fitting a Bath – How to Install a New Bathtub

This post may contain affiliate links. If you buy a product or service from an affiliate such as Amazon after clicking a link on this website, we earn a commission from qualifying purchases.

Installing a bath isn’t a particularly difficult project; as long as you plan thoroughly and work in a methodical fashion you should be able to achieve a satisfactory end result. Here we work through the steps for installing a new bath in the order you are likely to encounter them

The first step should, of course, is to turn off the water supply.

1) Fit the pipework to your new bath

If you have decided to place your new bathtub in a different location to the old one, or if the new model has the tap holes located in a different position, you are faced with the task of installing some new pipework. It makes sense to do this after you have removed the old bathtub and before you have fitted the new one, as you will have plenty of room to work.

Be sure to take a measurement of where the bath will fit, the pipe positions and also where the waste pipe is situated. You can then use a pencil to make visible reference points on the wall.

Next, you should fit any new supply pipes that are required or add spurs to the existing ones, ensuring that the pipes finish no more than 300mm away from where the tap will be positioned. This should allow ample room for manoeuvre when it comes to connecting the taps to the water supply using flexi-hoses.

If for any reason you are unable to finish the pipework less than 300mm from the tap connection, there are longer flexi-hoses available to accommodate for this.

2) Fix the feet to your new bath

The next step is to fit the feet to the underside of the bath. The best approach here is to tip the bath completely over rather than trying to balance on its side. Ideally, you should leave any protective wrapping on the bath whilst you do this to prevent damage. It is advisable to lay a protective sheet down on the floor for additional cushioning.

If you have a traditional style or original vintage cast iron bath then it may be that the feet are of the ball and claw design. As these feet are intended to be on show, they will usually be attached to a predetermined position using the supplied bolts, resulting in a symmetrical finish.

With more modern acrylic baths that are intended to be finished off with a side panel, the feet tend to be attached to a supporting frame, which must be fitted to the underside of the bath.

Refer to the instructions that came with the bath to ensure that you set the feet in the correct position.

Feet positioning is extremely important and getting it wrong can result in undue stress to the bath, which could in some cases result in cracking. With this in mind, it is a good idea to double-check you have them all in the right position before advancing to the next stage.

3) Adding the taps to your new bath

Fitting the taps, waste and overflow connections once the bath is in place is both difficult and frustrating, so do this before you manoeuvre the bath into the desired position. Start by positioning the supplied rubber or plastic sealing washer over the tail of the mixer tap, before sliding it through the designated tap hole, so that it sits between the rim of the bathtub and the base of the tap.

If you have individual taps for hot and cold, you will of course have to carry out this stage twice – remember that the hot tap should be operated by the left hand and the cold by the right hand.

Once you have the tap or taps in position on the bath rim, you can then place the supplied plastic nut over the thread of the tail and tighten. Use a spanner to ensure that the taps are nice and tight and also check  they are facing perfectly forward. You can now attach some 22mm flexi-hoses to the tap tails as required.

Once the flexi-hoses are in position it is worth giving the taps a double check that they are in line and all fastenings are sufficiently tight. Having to go back to straighten taps or address a leak once the bath is in place can prove problematic – especially if you opt to tile around the sides of the bath.

4) Waste pipe and overflow

In most instances, bathtubs are designed to take a combined waste and overflow unit, of which there are two standard types – a banjo unit and a compression unit.

A banjo unit has a separate overflow connection, which attaches to the bottom of the trap. In contrast, the overflow of a compression unit connects directly to the trap, making it pretty much impossible to make a mistake when fitting them.

So instead we will focus on how to fit a banjo unit, with the tips provided being transferable if you have a compression unit.

Where you are looking to utilise a banjo waste unit, you should first fasten the overflow pipe to its inlet. Now you can fit the rubber washer onto the overflow grille, before placing the overflow boss into the overflow hole in the bath and screwing it to the grille.

Positioning a cloth over the outer surface of the grille is a good way to avoid the chrome being damaged when tightening.

Before you fit the waste outlet, be sure to position the rubber washer on the tail and also add some silicone sealant to really safeguard against the likelihood of any leaks. The waste outlet can then be positioned in the waste hole and attached to the waste fitting.

It is a good idea at this point to apply some plumber’s tape around the thread at the bottom of the waste fitting to prevent leaking. Once you have done that you can tighten the trap onto the tail of the waste fitting using the plastic nut.

5) Levelling your new bathtub

With the bathtub in position, you are now ready to check that it is level. To do this, use a spirit level and make a pencil mark around any walls that the bath is touching. You can then move adjustable legs up and down as required until you find the right level.

Now give the bath a final check by positioning the spirit level on its rim along its length and width.

Where you have a bath with ball and claw feet, or other styles that are not adjustable, the tub should be pretty level. However, if you wish to make some slight adjustments you can do this by introducing fine bolts or washers to the required legs.

6) Applying sealant to your new bath

The final step of the process is to apply a suitable sealant, using a sealant gun, around the rim of the bath to prevent water from leaking or causing damp.

First, remove any moisture or dust from both the bath rim and wall surface.

Now fill the bath about three-quarters full, which will allow for any movement that may occur during usage and reduce the chances of the sealant cracking. Before you can use the sealant you must cut off the nozzle at the right place to allow an appropriate amount of sealant to escape.

Apply the sealant along the joint of the bath and wall using a smooth motion – don’t squeeze the gun too hard. Try to work on a length of 45–60cm at a time, using a wet fingertip to smooth the sealant down for a perfect finish, before moving onto the next section.

You will need a damp cloth at this point to keep your finger clean after each smoothing action and tidy any that accidentally spilt onto the bathtub. Now wait for the sealant to properly dry, which will usually take 4-6 hours, before emptying the bath.

Keep a lookout for any cracks in the sealant over the next few days and apply an additional thin layer in any areas that are necessary.

Job done.