Thinking about tackling a DIY toilet installation? Good on you. Replacing an old, inefficient, or damaged toilet can modernise your bathroom and save you money on your water bill. It’s a project that seems straightforward on the surface—unbolt the old, bolt on the new. But as any master plumber will tell you, the devil is in the details.

This guide isn’t just a list of steps. It’s your onsite supervision from the pros at SPS Plumbing. We’ll give you the clear, detailed, and cautious advice you need to approach this job with confidence, or to know with absolute certainty when it’s time to call a licensed tradie. Let’s get into it.

Thinking twice? That's smart. If you’ve read this far and already feel out of your depth, trust that instinct. Call SPS Plumbing on (02) 9072 0760 for a fixed-price, expert toilet installation. We handle the heavy lifting, the messy surprises, and the guarantee that it’s done perfectly the first time.

Is This a Job For You? A Pre-Start Checklist

Before you swing a single spanner, let's be brutally honest. This job requires more than just willpower. If you're determined to DIY, our top DIY plumbing tips can help you avoid common disasters.

Strength: A one-piece toilet can weigh 45kg+.
Flexibility: You’ll be working on the floor in a tight space.
Problem-Solving: What will you do if the flange is rusted or the floor is rotten?
A Helper: Seriously, do not attempt to lift and position a toilet bowl alone.

Stop immediately and call a professional if:

The floor around the old toilet feels soft or looks water-damaged.
The existing plumbing is very old (common in Sydney’s heritage homes) and the bolts are completely rusted.
Your bathroom has terrazzo or expensive tiling you cannot risk damaging.
You discover the sewer pipe is damaged once the toilet is removed.

What You'll Need: Your Pro-Grade Tool Kit

A successful toilet installation hinges on the right gear. Here’s what you’ll need, with a quick trip to Bunnings in mind:

New Toilet: Ensure it’s WELS 4-star rated for water efficiency.
Tools: Adjustable spanners, screwdrivers, a hacksaw (for cutting stubborn bolts), a putty knife, and a spirit level.
Supplies: A new wax ring seal (buy a spare!), closet bolts (often come with the toilet), a new flexible water supply line (don’t reuse the old one), and plumber’s tape.
Safety: Heavy-duty rubber gloves, safety glasses, and rags/old towels for the inevitable mess.
The Pro’s Secret: A second, smaller wax ring. If the first one gets compromised during positioning, you’ll thank us.

Step 0: The Most Important Step – Measure Twice, Buy Once

This is the most common DIY mistake. You must get the rough-in measurement correct. The toilet rough-in is the distance from the wall (not the skirting board) to the centre of the sewer outlet pipe in the floor. In Australia, this is almost always 185mm or 230mm. Measure yours precisely. A toilet with the wrong rough-in will not fit, leaving an unsightly and unhygienic gap.

The Step-by-Step Guide to Toilet Replacement

Step 1: Shut Down & Empty the Old Warrior

Turn off the water supply tap located at the wall behind the toilet. Flush the toilet and hold the handle down to drain as much water as possible from the cistern. Use a sponge and a bucket to remove all remaining water from the cistern and bowl. Disconnect the water supply line from the wall tap.

Step 2: Disconnect and Remove the Old Toilet

Remove the plastic caps covering the bolts at the base of the toilet. Unscrew the nuts. If they’re rusted, a few drops of penetrating oil can help. As a last resort, use your hacksaw to carefully cut the bolts.

The toilet is now only held by the wax seal. Rock it gently from side to side to break the seal. This is the two-person lift. Lift straight up to avoid damaging the sewer pipe. Have a rag ready to stuff into the exposed drain hole immediately to stop sewer gases and prevent debris from causing a blocked drain.

Step 3: Prepping the Battlefield

Scrape off the old wax ring residue from the flange (the metal or plastic ring on the floor) using your putty knife. This is a critical step for a good seal on the new toilet.

Inspect the closet flange. Is it cracked? Is it level with or slightly above the finished floor? Is it securely bolted to the floor? If it’s damaged, sunken, or loose, this is a major problem. A compromised flange is the primary cause of leaks and wobbly toilets.

Hit a snag? This is where many DIY dreams end. If that flange isn’t perfect, your new toilet will leak and rock. Fixing or replacing a flange is a pro’s job. Don’t risk it. Call SPS Plumbing on (02) 9072 0760 for a swift, permanent solution.

Step 4: Setting the New Throne

Place the new wax ring onto the flange (some pros prefer to place it on the toilet outlet—both methods work). Press the new closet bolts into the slots on the flange.

With your helper, carefully lower the new toilet bowl straight down onto the bolts. Do not twist, rock, or shift it once it makes contact. Your body weight is enough to compress the wax ring and form the seal. Check it’s level side-to-side and front-to-back. Place the washers and nuts on the bolts and hand-tighten. Then, using a spanner, alternate between bolts, tightening each a little at a time. Do not overtighten! You will crack the porcelain ceramic. The toilet should not move or rock at all.

Step 5: Attaching the Cistern & Hardware

If you have a two-piece toilet, now is the time to assemble and mount the cistern onto the bowl, following the manufacturer’s instructions. Use the provided tank-to-bowl bolts with rubber washers, again tightening evenly and cautiously. Install the seat and the inlet valve and flush mechanism inside the cistern.

Step 6: The Moment of Truth – Reconnection & Test

Reconnect the new flexible water supply line to the inlet valve and the wall tap. Turn the water supply back on slowly and let the cistern fill. Check for leaks at the water supply connection, the tank bolts, and the inlet valve connection.

Once full, flush the toilet several times. This is crucial: get on your hands and knees and check around the base of the toilet for any sign of moisture. A single drop indicates the seal has failed.

When to Put Down the Tools and Call SPS Plumbing

Call our toilet repairs team immediately if you see any of these red flags.

A cracked or damaged flange.

Water leaking from the base after installation.
The toilet rocks on what appears to be a solid floor.
You damage a pipe or fitting during the process. (This is a job for an emergency plumber).
You simply can’t get it to stop leaking from any connection.

Frequently Asked Questions

How long does it take to replace a toilet?

An experienced plumber can do it in 1-2 hours. A competent DIYer might take 3-4 hours, accounting for problems and careful work.

What is the rough-in distance?

In most Australian homes, it’s 185mm or 230mm. Always measure your specific setup.

Can one person install a toilet?

We strongly advise against it. Lifting and positioning the bowl alone is dangerous for you and risks damaging the toilet and the plumbing.

Why is my new toilet leaking from the base?

The wax ring seal has failed. This is usually caused by an uneven flange, the toilet not being set straight, or the toilet being rocked after setting. It must be fixed to prevent floor damage.

What is the best toilet brand in Australia?

We often recommend Caroma, Caroma, and Methven for their reliability, quality, and compliance with Australian standards.

Conclusion: You’ve Got This (Or We Do)

You made it to the end. That shows you’re diligent and care about doing the job properly—the most important trait of any DIYer. Replacing a toilet is a big job, and there’s no shame in calling for backup.

If you followed every step and have a perfectly functioning, leak-free throne, we tip our hats to you. Fantastic work.

But if you’re staring at a wobbly base, a rusty flange, or a puddle of water, the most professional move you can make is to call in the experts. For a clear, upfront toilet installation cost in Sydney (or to understand how much plumbers usually charge), give SPS Plumbing a call. We’ll get your bathroom back in action, guaranteed.

Call SPS Plumbing today on (02) 9072 0760 for a fast, flawless, and fixed-price toilet installation.