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Bathroom renovations go wrong in a specific, predictable way more often than any other: the plumbing gets treated as an afterthought instead of the first thing planned. Tiles get chosen, a vanity gets ordered, and only then does someone ask where the new shower drain actually needs to sit relative to the existing waste pipe.
Getting the plumbing sequence right from the start saves time, money and a lot of frustration partway through the job. This checklist walks through what to plan, check and confirm at each stage of a bathroom renovation, from the very first decisions through to final sign-off.
Before the Renovation Starts
Get a plumbing inspection first
Before finalising any design, have a plumber assess your existing pipework, water pressure and drainage. Older Gold Coast homes in particular may have ageing pipes that are worth addressing while the walls are already open, rather than tiling over a problem.
Decide if fixtures are moving
Relocating a toilet, shower or vanity even by a small distance can mean rerouting drainage pipes under the slab or through the wall cavity, which significantly affects both cost and the renovation timeline.
Check your hot water system capacity
If you're adding a second shower head, a bigger bath, or an ensuite, confirm your current hot water system can handle the extra demand, or budget for an upgrade as part of the renovation.
Confirm compliance requirements
Bathroom plumbing work in Queensland needs to meet the National Construction Code and AS/NZS 3500 standards, and certain work legally requires a licensed plumber, not just a builder or tiler.
Choosing Fixtures With Plumbing in Mind
- Toilets: Confirm the new toilet's outlet position matches your existing waste pipe, or budget for relocation work if it doesn't
- Showers: Check the drain position aligns with the fall of the floor, and consider a linear drain if you're going for a step-free, accessible design
- Baths: Freestanding baths need floor-mounted or wall-mounted tapware planned early, since the pipework location has to be finalised before tiling
- Vanities: Confirm the basin's waste and supply line positions match the vanity's cutouts before it's installed
- Taps and mixers: WaterMark-certified fixtures are a compliance requirement, so check for the certification mark before purchasing
During the Renovation: What the Plumber Needs to Do First
- Rough-in plumbing before waterproofing. All pipework, whether relocated or upgraded, needs to be installed and pressure-tested before the waterproofing membrane goes down.
- Waterproofing inspection. A compliant waterproofing job typically needs an inspection or certification before tiling begins, particularly around the shower and any wet areas.
- Tiling around fixed plumbing points. Once pipework is finalised, tiling can proceed around the confirmed positions for the toilet, shower drain, and tapware.
- Fixture installation. Toilets, vanities, showers and baths are connected only once tiling and waterproofing are fully complete and cured.
- Final pressure and leak testing. Before the bathroom is considered finished, every connection should be tested for leaks under normal water pressure.
Common Bathroom Renovation Plumbing Mistakes
Tiling before pipework is finalised
If tiling happens before drain and supply positions are locked in, moving them afterwards means breaking tiles and starting that section again.
Underestimating hot water demand
Adding a second bathroom or a larger shower without checking hot water capacity often leads to a system that can't keep up, discovered only after everything is finished.
Skipping the compliance step
Unlicensed plumbing work in a renovation isn't just a compliance risk; it can also cause issues when selling the property later, since it may not be covered by the required compliance certificate.
Poor shower floor fall
If the floor isn't graded correctly toward the drain, water pools instead of draining, which is a difficult and expensive fix once tiling is complete.
When to Bring In a Licensed Plumber
For any bathroom renovation, a licensed plumber should be involved for:
- Relocating or altering drainage and supply pipework
- Rough-in plumbing before waterproofing and tiling
- Connecting new toilets, showers, baths and vanities
- Final compliance testing and certification
- Any gas work, if you're adding a gas hot water system or heated towel rail
Under Queensland law, most plumbing work beyond very minor tasks legally requires a licensed plumber, and using one protects you if issues arise after the renovation is complete.
If you're planning a bathroom renovation on the Gold Coast, get in touch with our team early in the planning process so the plumbing is sequenced correctly from day one.
After the Renovation
- Keep copies of all compliance certificates and plumbing documentation
- Test all fixtures for proper drainage and pressure within the first week
- Watch for any signs of leaks around new tiling in the following months
- Schedule a follow-up check if you notice any slow drainage or water pooling
Final Thoughts
The bathrooms that end up needing rework after a renovation almost always share the same root cause: plumbing decisions made too late in the process, or worse, after the tiling was already down. Involving a licensed plumber from the planning stage, not just for the final connection, is the single biggest factor in keeping a bathroom renovation on time and on budget.
Call Coastal Plumbing Professionals on 1300 590 085 to talk through the plumbing side of your Gold Coast bathroom renovation before you start.
Frequently Asked Questions
Do I need a licensed plumber for a bathroom renovation, or can my builder handle it?
In Queensland, most plumbing work legally requires a licensed plumber. A builder can manage the overall project, but plumbing connections and alterations need a licensed tradesperson.
Can I move my toilet or shower to a different spot in the bathroom?
Yes, but it usually means rerouting drainage pipes, which adds cost and time. It's best confirmed early, before fixtures and tiles are chosen.
Will my hot water system cope with a bigger bathroom?
Not always. If you're adding a second shower or a larger bath, it's worth having your hot water system's capacity checked as part of the renovation planning.
What happens if the shower floor isn't graded properly?
Water will pool instead of draining toward the outlet, which is a common and costly issue to fix once tiling is finished, so it's worth checking before that stage.
When should I involve a plumber in the renovation timeline?
As early as possible, ideally during the design phase, so fixture positions, hot water capacity and compliance requirements are all factored in from the start.
Resources
- National Construction Code | Australian Building Codes Board
- AS/NZS 3500 Plumbing and Drainage Standards
- Home renovations | Queensland Building and Construction Commission
