Fitting a bath is a substantial DIY project, but a manageable one if the preparation is thorough and the steps are followed in the right sequence. This guide covers every stage of a standard bath installation – from removing the old bath and preparing the space, through to plumbing connections, sealing, and fitting the bath panel. It also covers the specific considerations for different bath types and explains clearly where a professional should be involved rather than a confident DIYer.
Before you start: what to check
Unpack and inspect immediately. As soon as the bath is delivered, unpack and inspect it thoroughly for damage or surface marks. It is far easier to arrange a replacement before installation begins than after. Check that all components in the fittings box are present – legs, brackets, fixings, and any supplied waste or overflow parts.
Measure the space. Confirm the bath dimensions fit the intended position with adequate clearance for access during installation. Measure the distance from the wall to the waste outlet and confirm alignment with the existing drain. Allow for the depth of any wall tiles or tile backer board that will be applied after installation.
Check the subfloor. The floor must be level and structurally sound. A bath filled with water weighs considerably more than it does empty – a standard 1700mm acrylic bath holds approximately 150–200 litres. The subfloor must support the combined weight of the bath, water, and user without flexing. If there are any signs of rot, damage, or unevenness, address them before fitting.
Confirm the waste pipe alignment. This is the one aspect of a bath installation most likely to require a plumber. If the new bath's waste outlet position does not align with the existing drain, the waste pipe needs to be rerouted. Do not attempt this unless you are confident with waste plumbing – an incorrectly graded waste pipe blocks regularly and can leak behind the bath panel, leaving no visible signs until the damage is significant.
Turn off the water supply before you do anything else. Use the isolation valves under the existing bath if they are accessible, or turn off the main stopcock. Open the taps fully and allow the pipes to drain completely before disconnecting anything.
Tools and materials needed
Tools:
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Retractable tape measure
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Spirit level
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Adjustable wrench and pipe wrench
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Standard and cross-head screwdrivers
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Power drill and appropriate drill bits
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Hole saw (for tap holes if not pre-drilled)
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Hacksaw
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Putty knife
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Sealant gun and smoothing tool
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Pencil
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Safety goggles and protective gloves
Materials:
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PTFE tape (plumber's tape)
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Silicone sealant – sanitary grade, mould-resistant
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Masking tape
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Bathroom wastes and overflow kit (if not supplied)
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Bathroom taps (if not supplied)
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Wooden battens (to protect the floor and support the bath during leg fitting)
Step 1: Remove the old bath
Turn off the water supply and open the taps to drain the pipes fully. Place towels or rags around the base of the existing bath to catch residual water when pipes are disconnected.
Remove the bath panels if fitted, as most clip or unscrew from the bath frame. Disconnect the tap supply pipes by loosening the flexible connectors at the tap tails. Have a bucket ready to catch any water remaining in the pipes. Disconnect the waste and overflow pipes by unscrewing the trap and pulling the waste pipe free.
Using a putty knife or utility knife, cut through the sealant between the bath and the wall along the full length of the bath. Undo any wall brackets or fixings securing the bath in place.
With at least one other person assisting, lift the bath clear of its position. Some baths – particularly steel or cast-iron baths – are extremely heavy and should not be moved without adequate assistance and appropriate manual handling techniques.
Once the bath is removed, clear the area completely. Check the subfloor and walls for damp, mould, or damage. Allow everything to dry thoroughly before proceeding.
Related: How to Plan a Bathroom Renovation
Step 2: Assemble the bath feet and legs
Place the new bath face down on a protected surface – lay cardboard or a blanket on the floor to prevent surface damage.
Fit the brackets to the underside of the bath using the fixings provided. Attach the legs to the bracket positions. Most standard acrylic and steel baths use adjustable screw feet that allow the height to be set independently at each corner and at any centre support points.
Set all legs to roughly the same height before standing the bath upright. Standing on battens at this stage helps protect the floor and provides clearance to adjust leg height once the bath is in position.
Step 3: Fit the bath taps and waste before positioning
It is significantly easier to fit the taps and waste to the bath before it is in its final position against the wall. Working on the bath while it is accessible from all sides saves considerable time and effort compared to attempting the same work in a confined space.
Fitting the taps: insert the tap tails through the pre-drilled tap holes in the bath. Place the gasket or rubber seal between the tap body and the bath surface. From underneath, apply a back nut or retaining bracket as supplied and tighten with an adjustable wrench or basin wrench. Wrap PTFE tape around the tap tail threads before connecting the flexible supply hoses. Do not overtighten.
Browse our bath taps if you need to choose new taps to fit at this stage.
If the bath does not have pre-drilled tap holes and you are fitting deck-mounted taps, use a hole saw to drill the tap holes at this stage.
Fitting the waste and overflow: apply a thin bead of silicone sealant to the underside of the waste flange before inserting it into the waste outlet. Tighten the waste from beneath using the supplied nut and washer. Attach the overflow pipe to the overflow outlet. Most bath waste kits include a flexible overflow pipe that connects the overflow to the waste trap. Check all connections are hand-tight before the bath is positioned, and fully tighten after final positioning.
Browse our bathroom wastes and traps for waste kit options.
Related: What Accessories Do I Need to Buy Along With a Bath?
Step 4: Position and level the bath
With the taps and waste fitted, carry the bath into its final position. Lay wooden battens on the floor at 90 degrees to the floor joists if you are installing on floorboards – this distributes the bath's weight more evenly and protects the floor surface.
Place the bath against the wall and use a spirit level to check that it is perfectly level along the length and across the width. Adjust the height of each leg independently until the bath is level. An uneven bath will drain unevenly, and water will pool at the low end rather than running to the waste.
Once level, mark a pencil line on the wall at the top edge of the bath. Note the distance from this line to the floor – this must match the height of the bath panel. Also, mark all wall bracket fixing positions on the wall before moving the bath away to drill.
Move the bath back from the wall, drill the wall-fixing positions, and insert the appropriate wall plugs for the wall type. Attach the wall fixing brackets to the side of the bath.
Move the bath back into its final position and secure the wall brackets to the wall with the supplied screws. Check the level again. Secure the legs to the floor through the holes in the feet if the floor type allows – appropriate for solid floors and most timber floors with adequate joist support below.
Step 5: Connect the plumbing
Connect the flexible supply hoses from the tap tails to the hot and cold water supply pipes. Hot supply to the left inlet, cold to the right. Wrap PTFE tape around all threaded connections before tightening. Hand-tighten first, then use an adjustable wrench for a final quarter turn. Do not overtighten – this is the most common cause of cracked tap tails and damaged connections.
Connect the waste trap to the waste outlet beneath the bath. Ensure all internal washers within the trap are correctly seated. Connect the waste pipe from the trap to the existing drain. The waste pipe must run to the drain with a continuous downward fall – typically a minimum fall of 1 in 40 (25mm drop per metre of run). A flat or reverse-fall waste pipe will not drain properly.
Turn the isolation valves back on or reopen the main stopcock. Check every connection carefully for drips. Wipe the connections dry with a cloth, then check again after five minutes.
Step 6: Seal the bath
This step is critical and the most commonly rushed. Incorrect sealant application is the primary cause of water getting behind the bath and into the wall structure.
Fill the bath with water before applying any sealant. This is not optional. A bath filled with water flexes slightly under its own weight and pushes slightly away from the wall at the joint. If sealant is applied to an empty bath and then filled, the movement can stretch and crack the sealant. Seal with the bath weighted and the sealant cures in the correct flexed position.
Apply a strip of masking tape along the wall above the sealing area and a second strip along the bath surface below it, leaving a gap of 5–6mm between the two strips. This is where the sealant bead will sit.
Load a cartridge of sanitary silicone sealant into the gun. Apply a continuous, even bead along the entire length of the joint in a single smooth pass. Do not stop and start. Immediately smooth the bead with a dampened smoothing tool or finger dipped in soapy water, pressing it into the joint with a slight concave profile that slopes water back into the bath.
Remove the masking tape immediately while the sealant is still wet, pulling it back on itself at a 45-degree angle. Do not touch the sealant for at least 24 hours. Leave the bath full of water throughout the curing period.
Read more: How to Seal a Bath
How to fit a bath panel
Bath panels are fitted after the bath is plumbed, sealed, and all connections are confirmed watertight. Most panels are fixed using clips or a batten system rather than being glued in place, allowing access to the plumbing beneath if needed.
How to fit a front bath panel
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Measure the height from the floor to the underside of the bath rim and trim the panel height if necessary. Most bath panels have a small amount of adjustable height at the base.
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Position the panel flush against the front of the bath. The top edge of the panel should sit tight against the underside of the bath rim.
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Fix the panel using the clips, brackets, or batten provided by the manufacturer. Most front panels are fixed to a horizontal batten screwed to the floor, with the panel clipped into a channel under the bath rim at the top.
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Check the panel is flush and level. Apply a bead of silicone along the floor at the base of the panel where it meets the floor surface – not between the panel and the bath, as this must remain accessible.
How to fit a side bath panel
Follow the same process as the front panel, measuring and trimming to fit the end of the bath. Where a front and side panel meet at a corner, most systems use a corner infill strip or channel. Some manufacturers supply corner pieces – check the instructions before cutting.
How to fit a bath panel without the manufacturer's brackets
If the bath did not come with fixing hardware, fit a 50x25mm timber batten to the floor directly under the bath's front edge, secured with screws. A second batten under the side panel, if applicable. The panel clips into the channel under the bath rim at the top and rests against the floor batten at the bottom.
For further inspiration on panel options and styles, see our bath panel ideas guide.
Special considerations for different bath types
Fitting a freestanding bath
Freestanding baths do not have panels and do not fix to walls or floors in the same way as an inset bath. The installation is simpler in some respects – no wall brackets, no panels – but the plumbing arrangement is different. Floor-mounted tap and waste connections are the norm, and the supply pipes run below the floor to emerge at the correct positions.
The floor must be completely flat and structurally sound. A freestanding bath is heavy and sits entirely on the floor with no wall support. Confirm the floor can support the weight before proceeding, and check there is no flex underfoot in the intended position.
Fitting a shower bath
A shower bath is installed in the same way as a standard inset bath, with the additional consideration of the shower valve and supply. The shower valve supply connection should be made at the first fix stage if the wall is being tiled, so the concealed section of the valve is in place before tiles are applied. See our shower valves range for suitable options.
A bath shower screen is fitted after the tiling is complete. Follow the screen manufacturer's instructions for wall-fixing positions, and confirm that the wall is structurally sound at those points before drilling.
Related: Shower Bath Ideas
Fitting a whirlpool bath
A whirlpool bath requires both plumbing and electrical connections. A Part P certified electrician must carry out all electrical work in a bathroom – this is a legal requirement, not a preference. The jet direction and motor positioning require specific technical knowledge. This is not a DIY installation – always use a qualified professional team.
Fitting a steel bath
Steel and cast iron baths are significantly heavier than acrylic equivalents. A full-size cast iron bath can weigh over 100kg before water is added. Always ensure adequate assistance with lifting and positioning, and confirm the floor's structural capacity before installation.
When to call a professional
For most competent DIYers, fitting a standard acrylic inset bath with existing plumbing in the same position is achievable. Call a professional for:
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Moving the waste pipe position. Rerouting the soil stack or drain requires compliance with Building Regulations, and incorrect installation can cause persistent blockages or concealed leaks within the floor or wall structure.
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New plumbing from scratch. First-time bath installations in a room not previously used as a bathroom require a full plumbing installation from the mains supply and drainage system.
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Any whirlpool or spa bath installation. Electrical connections in wet zones require a Part P-certified electrician regardless of how simple the installation appears.
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Any signs of structural damage. Rotten joists, damaged subfloor, or signs of previous water damage must be properly assessed and repaired before a bath is fitted above them.
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Complex drainage rerouting. Even experienced DIYers can struggle with the precise fall requirements for bathroom waste pipes – an incorrectly graded run costs more to fix after tiling than a plumber costs before it.
Installing a bath FAQs
Can you fit a bath yourself?
For a straightforward like-for-like replacement of a standard acrylic bath with the plumbing in the same position, yes – it is a manageable DIY project for a competent and patient person. The mechanical assembly of the legs, positioning, and fitting the waste and taps are all DIY-appropriate. The plumbing connections themselves require care and attention to get right, and any doubt about the waste alignment, supply pipework, or the structural condition of the floor is best resolved by calling in a plumber.
What holds a bathtub in place?
A standard inset bath is held in place by a combination of wall brackets and the bath's weight. The legs sit on the floor but are not always screwed down. Wall brackets are fixed to the side of the bath and screwed to the wall studs or wall plugs in masonry. The bath panel at the front and sides is fitted separately and does not provide structural support.
How much do plumbers charge to install a bath?
In the UK, a plumber typically charges between £200 and £500 for a standard bath installation, depending on complexity, location, and whether any pipework needs to be adjusted. A full bathroom renovation involving repositioning the bath and rerouting plumbing will cost significantly more. Labour rates vary widely – always get at least two or three written quotes before committing.
Read more: How Much Does A New Bathroom Cost
What do you put under a bathtub when installing it?
Adjustable feet are the primary support for a standard inset bath. Wooden battens laid on the floor – particularly when installing on floorboards – help distribute the weight across the joists and protect the floor surface during positioning. In some installations, closed-cell expanding foam is used to fill the void beneath a freestanding bath to provide additional support and reduce resonance.
What are common bathtub installation mistakes?
Not filling the bath before applying sealant is the most common – the resulting cracked sealant allows water into the wall. Not checking the level before fixing it in place leads to drainage problems. Overtightening flexible tap connectors or waste nuts causes cracking and leaks. Fitting the bath panel before confirming all plumbing connections are watertight means removing the panel again when a drip is discovered. And not checking the waste pipe fall – a flat waste run that traps water, causing regular blockages.
Do you tile before or after fitting a bath?
Both approaches work, but fitting the bath first is generally recommended. With the bath in place, tiles can be run down to the bath rim and cut to the correct profile, giving a cleaner junction at the top edge. If tiling first, the bath must sit on top of the tiles, which raises it slightly and can affect panel height calculations. If tiling before fitting, ensure the tile height is accounted for in the bath leg adjustment.
Need any help fitting a bath?
A bath installation done carefully and in the right order is a project that delivers a genuinely satisfying result. The steps that matter most are also the ones most often rushed: checking the subfloor before fitting, levelling accurately before fixing, fitting the waste and taps while the bath is accessible, and sealing with the bath filled. Get that right, and the rest follows.
If you are still deciding on the right bath, browse our full range. For help choosing the right size, see our standard bath size guide. If you want to see our products in person or need any advice on fitting a bath, book a consultation with our expert team, visit our Birmingham showroom, or call us on 0121 753 0700.