Written by JSW Plumbing | Published on June 2025
A bathroom renovation plumbing checklist typically covers 8 to 12 key tasks, from inspecting existing pipes to booking a licensed plumber for final connections. Getting these steps right can save you thousands in rework costs. This guide walks Hornsby, Thornleigh and Hills District homeowners through every stage of the process, so nothing gets missed.
Assess Your Existing Plumbing Before You Start
Before any tiles come off or fixtures get ordered, you need a clear picture of what is already inside your walls and under your floor. Skipping this step is one of the most common and expensive mistakes homeowners make during bathroom renovations.
In older homes across Thornleigh and Hornsby, it is common to find copper pipes, galvanised steel, or even early PVC that is well past its service life. These materials may need replacing before new fixtures are installed.
Here is what to check before work begins:
- Locate your water shut-off valve and confirm it works correctly.
- Identify the age and material of existing supply lines and drain pipes.
- Check for signs of corrosion, mineral buildup, or past leaks behind the vanity and toilet.
- Note the position of your existing waste stack and how far fixtures will move from it.
- Confirm the current hot water system can meet the demand of any new fixtures you plan to add.
A licensed plumber can complete a pre-renovation inspection in one to two hours. JSW Plumbing offers this service to homeowners across the Hills District and can flag issues before they become costly surprises mid-renovation.
Understand Which Plumbing Work Requires a Licensed Plumber in NSW
In New South Wales, the law is clear. Any work that involves connecting to or altering water supply lines, drainage, or gas is classified as licensed plumbing work. Homeowners cannot legally do this work themselves.
This matters a lot for bathroom renovations because almost every task on your list will touch one of these systems.
| Task | DIY Allowed? | Licensed Plumber Required? |
|---|---|---|
| Replacing a showerhead | Yes | No |
| Relocating a toilet waste pipe | No | Yes |
| Installing a new basin | No | Yes |
| Moving hot water supply lines | No | Yes |
| Installing a heated towel rail (electric) | No | Licensed electrician required |
| Connecting a new bath or spa | No | Yes |
| Waterproofing membrane application | Sometimes | Varies by council |
Always confirm with your local council whether a plumbing permit is needed for your specific scope of work. Hills Shire Council and Hornsby Shire Council each have slightly different notification requirements for bathroom renovations.
Plan Your Fixture Layout and Pipe Routing Carefully
The position of your toilet, shower, bath, and basin affects every other plumbing decision you make. Moving fixtures further from the existing waste stack increases labour time, material costs, and the risk of drainage problems.
Gravity drainage in Australian homes is designed with specific fall ratios. A typical drain requires a 1 in 60 fall, meaning 1mm of drop for every 60mm of horizontal run. The further a new toilet or shower moves from the stack, the harder it is to maintain this fall under a concrete slab or timber floor.
Before finalising your layout, consider these planning points:
- Keep the toilet as close to the existing soil stack as possible to avoid costly re-routing.
- Position the shower waste close to an existing floor drain outlet where practical.
- Allow enough clearance for access panels behind freestanding baths and wall-hung cisterns.
- Confirm your new vanity position allows for supply line and waste connection without chasing long runs through tiled walls.
- If you are adding a double basin, account for the extra waste connection and venting requirements.
The JSW Plumbing team regularly helps homeowners in Thornleigh and surrounding suburbs review renovation plans before they are locked in. A quick conversation at this stage can save days of rework later.
Compare Plumbing Costs for Common Bathroom Renovation Tasks
Budgeting accurately for bathroom plumbing is easier when you know typical cost ranges for each task. Prices below reflect general market rates in the Hornsby, Thornleigh and Hills District area as of 2025.
| Plumbing Task | Estimated Cost (AUD) | Notes |
|---|---|---|
| Pre-renovation inspection | $150 to $300 | One to two hour assessment |
| Toilet relocation (same room) | $800 to $2,000 | Higher cost if slab needs cutting |
| New shower drain and rough-in | $400 to $900 | Depends on floor type |
| Basin supply and waste connection | $250 to $550 | Per basin |
| Bath waste and overflow installation | $350 to $700 | Freestanding baths cost more |
| Hot water system upgrade | $1,200 to $3,500 | Depends on system type and size |
| Full bathroom rough-in (new bathroom) | $2,500 to $6,000 | Labour only, excludes fixtures |
These are estimates only. Your actual costs will vary based on access, floor construction, fixture choices, and whether any existing pipes need replacing. Always get a written quote before work starts.
Follow a Stage-by-Stage Plumbing Checklist for Your Renovation
Breaking your bathroom renovation plumbing checklist into stages keeps the project on track and ensures nothing is missed between trades. Plumbing work typically happens in two phases: rough-in and fit-off.
Rough-in happens before tiling. Fit-off happens after tiling is complete. Both stages require a licensed plumber and should be coordinated with your tiler and builder.
Stage 1: Pre-Work (Before Demolition)
- Book a pre-renovation plumbing inspection.
- Confirm your scope of work and get a written quote.
- Check whether a plumbing permit is required with your local council.
- Order fixtures in advance so your plumber can confirm rough-in measurements.
Stage 2: Rough-In (After Demolition, Before Tiling)
- Relocate waste pipes and supply lines to suit the new layout.
- Install floor waste and shower base outlet at the correct height for your chosen tile thickness.
- Set toilet rough-in to the correct setout from the finished wall.
- Install in-wall cistern frames or bath filler rough-ins if applicable.
- Pressure test all supply lines before walls are closed.
Stage 3: Fit-Off (After Tiling)
- Connect and install toilet suite, basin, and tapware.
- Connect bath waste, overflow, and filler.
- Install shower head, rail, and mixer.
- Test all fixtures for leaks at full pressure.
- Confirm hot water temperature is set correctly (50 degrees at the outlet for safety).
Stage 4: Final Sign-Off
- Obtain a compliance certificate from your plumber if a permit was required.
- Keep all documentation for insurance and future sale purposes.
Check Waterproofing and Drainage Compliance for NSW Bathrooms
Waterproofing is technically a tiling and building task, but it directly affects plumbing performance. Poor waterproofing causes water to seep into subfloors and walls, which leads to serious structural damage and mould over time.
In NSW, bathroom waterproofing must comply with AS 3740, the Australian Standard for waterproofing of domestic wet areas. This standard specifies membrane types, application heights, and cure times before tiling can begin.
Key waterproofing points for Hornsby and Hills District homeowners:
- Shower recesses require waterproofing to a minimum height of 1800mm on all walls.
- The floor must be waterproofed across the entire wet area, not just the shower zone.
- Floor wastes must be correctly installed and bonded to the membrane before waterproofing.
- Allow 24 to 48 hours minimum cure time before tiling over most membrane products.
- If your home is on a concrete slab, check for any existing moisture issues before applying the membrane.
Your plumber should confirm that all floor wastes are at the correct finished height before the waterproofer starts. Getting this wrong means cutting up fresh waterproofing and tiles, which adds significant cost and delay.
FAQs on Bathroom Renovation Plumbing
Do I need council approval for a bathroom renovation in NSW?
Most cosmetic bathroom renovations do not require council approval in NSW. However, if you are moving walls, changing the room footprint, or doing significant structural work, you may need a Development Application or Complying Development Certificate. Always check with Hornsby Shire Council or Hills Shire Council before starting.
How long does bathroom plumbing rough-in take?
A standard bathroom rough-in typically takes one to two days for a licensed plumber. More complex renovations involving slab penetrations, pipe relocations, or in-wall cisterns can take three to four days. Booking your plumber well in advance helps keep your renovation on schedule.
Can I keep my existing waste pipes and just update the fixtures?
Yes, in many cases you can reuse existing waste pipes if they are in good condition and the new fixtures align with the current layout. Your plumber will inspect the existing waste system and confirm whether it is suitable. Older galvanised pipes are often worth replacing at this stage to avoid future blockage issues.
What is the standard toilet rough-in measurement in Australia?
The standard toilet setout in Australian bathrooms is 140mm to 165mm from the finished wall to the centre of the waste outlet. Most toilet suites are designed for a 140mm setout. Always confirm your specific toilet model’s requirements before the rough-in is done, as corrections after tiling are expensive.
How do I choose between a wall-hung and floor-mounted toilet for my reno?
Wall-hung toilets require an in-wall cistern frame and are better suited to bathrooms with tile or solid wall construction. They cost more to install but are easier to clean and give a modern look. Floor-mounted toilets are more affordable to install and easier to replace in the future. Your plumber can advise on which suits your wall construction and budget.
Should I upgrade my hot water system during a bathroom renovation?
A bathroom renovation is an ideal time to assess your hot water system. If your system is more than 10 years old, or if you are adding a second shower or bath, upgrading now avoids disruption later. Continuous flow gas systems and heat pump units are popular choices for Hills District homes due to their energy efficiency.
Wrap Up and Next Steps
A solid bathroom renovation plumbing checklist makes the difference between a smooth reno and a costly, stressful one. Plan your layout carefully, book your plumber early, and make sure all work meets NSW compliance standards.
JSW Plumbing works with homeowners across Hornsby, Thornleigh and the Hills District on bathroom renovations of all sizes. Whether you need a pre-renovation inspection, rough-in, fit-off, or all three, our licensed team is ready to help.
Call JSW Plumbing today or use the contact form on our website to request a free quote for your bathroom renovation.