Bathtub Installation Guide: How to Install a New Bathtub (DIY & Pro Tips)

🛁 From soaking tubs to alcove baths—complete guide to installing a new bathtub, including plumbing, leveling, and waterproofing

A long, hot bath after a stressful day is one of life’s simple pleasures. But when your old bathtub is cracked, stained, or simply outdated, you need a replacement. The question is: can you install it yourself, or should you call a professional?

Bathtub installation is one of the more challenging DIY plumbing projects. Bathtubs are heavy (50-100kg), awkward to maneuver, and require precise leveling and drain connections. A mistake can lead to leaks, water damage, and a ruined ceiling below.

I’ve helped hundreds of homeowners across South Africa with bathtub installations. The difference between a successful DIY and a disaster often comes down to preparation, the right tools, and knowing your limits.

This comprehensive guide will teach you everything about how to install a bathtub—from choosing the right type to step-by-step installation, common mistakes, and when to call a professional. Whether you’re in Gauteng, KwaZulu-Natal, or Durban, this bath fitting guide has you covered.

For related information, read our bathroom sink installation guide, shower installation cost guide, and bathroom renovation guide. Let’s get started.

🛁 Types of Bathtubs

Different bathtub types have different tub installation requirements:

• Alcove tub: Installed against three walls. Most common and DIY-friendly. Standard size 1500-1700mm. Requires access panel at one end.
• Drop-in tub: Drops into a deck or surround. Requires custom platform. More complex installation.
• Freestanding tub: Stands alone, visible from all sides. Elegant but requires floor-mounted faucet. Professional installation recommended.
• Corner tub: Fits into a corner. Often larger, may have jets. Complex plumbing required.
• Clawfoot tub: Vintage style on feet. Heavy, requires floor reinforcement.

For most homeowners, an alcove tub replacement is the most straightforward install bathtub project.

Read our bathroom plumbing guide for more on bathroom fixtures.

🛠️ Tools & Materials You’ll Need

Important: Bathtubs are heavy (50-100kg). You WILL need a helper for lifting and positioning.

Read our plumbing tools guide for more equipment information.

🔧 Step 1: Remove the Old Bathtub

Before you can install bathtub components, remove the old one:

1. Turn off water supply – Close isolation valves for the tub (usually under the house or in a access panel).
2. Disconnect plumbing – Remove the drain and overflow assembly. Disconnect water supply lines.
3. Remove the tub surround/tiles – Carefully remove tiles or surround panels around the tub.
4. Cut the tub (if necessary) – For cast iron tubs, use a sledgehammer (wear safety gear!). For acrylic/steel, use a reciprocating saw to cut into manageable pieces.
5. Remove the tub – Lift out in pieces or as a whole (get help—cast iron tubs weigh 150kg+).
6. Clean the area – Remove old adhesive, sealant, and debris. Inspect subfloor for water damage.

If you find subfloor damage, read our water leak repair guide before proceeding.

📏 Step 2: Prepare the Area

Proper preparation ensures a successful bath fitting guide:

1. Check the subfloor – Must be level, dry, and structurally sound. Repair any water damage.
2. Install blocking (if needed) – Add 2×4 blocking between studs to support the tub’s rim.
3. Position the drain – Ensure the waste pipe aligns with the new tub’s drain location.
4. Test fit the new tub – Place the new tub in position to check fit. Mark stud locations for blocking.
5. Remove tub and prepare – Apply mortar or spray foam to the subfloor where the tub will sit (provides support and prevents flexing).

Why mortar/foam is important: A bathtub that flexes under weight will crack the tile or grout and may develop leaks. Solid support is essential.

💧 Step 3: Install the Drain Assembly

Install the drain before final positioning—it’s much easier to access:

1. Apply plumber’s putty around the underside of the drain flange
2. Insert the drain flange into the tub drain hole
3. From underneath, install the gasket and tightening nut
4. Tighten securely (don’t overtighten—can crack the tub)
5. Install the overflow assembly (the upper drain that prevents overfilling)
6. Connect the drain pipe to the waste tee

Pro tip: Test the drain for leaks before final positioning. Fill the tub with a few inches of water and check underneath.

📏 Step 4: Position and Level the Tub

This is the most critical step in how to install a bathtub correctly:

1. Apply silicone sealant to the wall studs (where the tub rim will contact)
2. With a helper, carefully lower the tub into position
3. Press the tub firmly into the sealant
4. Check level in both directions (front-to-back and side-to-side)
5. Use plastic shims under the tub feet to level as needed
6. Fill the tub with water (this adds weight and ensures proper settling)
7. Check level again—adjust shims if needed
8. Secure the tub to the wall studs (some tubs have mounting flanges)

🔧 Step 5: Connect Water Supply & Drain

Now connect the final plumbing connections:

1. Connect the drain: Attach the P-trap to the drain assembly. Tighten slip nuts hand-tight plus 1/4 turn.
2. Connect water supply: Attach flexible supply lines to the tub faucet valves.
3. Connect to house supply: Connect supply lines to isolation valves.
4. Install the tub faucet/spout – Follow manufacturer instructions.
5. Turn water on slowly – Check for leaks at all connections.
6. Fill the tub and test drain – Check for leaks around drain and overflow.

Read our how to fix a leaking pipe guide for leak troubleshooting.

✅ Step 6: Seal and Finish

Final steps for your bathtub installation:

1. Apply silicone sealant – Run a bead of bathroom-grade silicone along the tub-to-wall joint.
2. Smooth the sealant – Use a wet finger or tool to create a smooth, watertight seal.
3. Install the tub surround/tiles – Complete tiling or install the surround panels.
4. Install access panel – If the tub has an access panel for plumbing, install it.
5. Caulk the perimeter – Apply sealant around the tub base where it meets the floor.
6. Wait for curing – Allow 24 hours for sealant to cure before using the tub.

Test again: After sealant cures, fill the tub and check for leaks one final time.

🛠️ DIY vs Professional Bathtub Installation

Is how to install a bathtub a DIY project? Here’s the reality:

Professional cost: R2,500-R6,000 for bathtub installation labour. In Durban or Umhlanga, rates may vary.

Read our how to choose a contractor guide for finding the right professional.

💰 Bathtub Installation Cost Guide

Here’s what to budget for bathtub installation:

DIY saves: R2,500-R4,500 in labour costs—worth it if you’re confident.

❌ 5 Costly Mistakes to Avoid

📋 Real-World Bathtub Installation Case Studies

❓ Frequently Asked Questions About Bathtub Installation

✅ Final Thoughts: Know Your Limits, Enjoy Your Bath

A new bathtub can transform your bathroom into a relaxing retreat. Bathtub installation is challenging but achievable for handy DIYers—especially alcove replacements. But knowing your limits is crucial. A failed installation can cause water damage costing far more than professional installation.

Key takeaways for South African homeowners:

• Alcove tub replacement is DIY-friendly – freestanding and cast iron are not
• DIY cost: R2,500-R6,000 (tub + materials) – Professional cost: R5,500-R12,000+
• Always level with water in the tub – critical for proper drainage
• Use mortar or foam under the tub – prevents flexing and tile cracks
• Test for leaks before finishing – fix leaks before tiling
• Get a helper – tubs are heavy (50-100kg+)
• Call a pro for freestanding, drain relocation, or cast iron

Your action plan: Assess your tub type and skill level. For a standard alcove replacement with the same drain location, DIY is achievable with a helper and this guide. For anything complex, get quotes from 3 verified plumbers through ServiceLink SA. Either way, enjoy your new bath.

For more information about bathtub installation and bathroom plumbing, explore our related resources:
bathroom sink installation guide,
shower installation cost guide,
bathtub installation guide,
bathroom renovation guide,
and toilet installation cost guide.
Our what is ServiceLink SA and
how ServiceLink SA works pages explain our verification process.
See our service areas page for bathtub installation coverage in your region.