Moving the toilet is the most-asked layout change question we get during bathroom reno quoting. The short answer is yes, almost always possible. The longer answer involves slab coring, new drainage with proper fall, and a chunk of additional cost on top of the base reno quote.
The slab coring process
Most Gold Coast homes are slab-on-ground (concrete slab foundation). The existing toilet drains down through the slab into the sewer line below. Moving the toilet means:
- Capping the existing slab penetration
- Coring (drilling) a new slab penetration at the new toilet position, typically 100mm diameter
- Running new drainage from the new penetration to the sewer line, with proper fall (1:60 minimum to AS3500)
- Connecting to the existing sewer line
- Sealing the penetrations against water ingress and ant entry
What it costs
- Plumbing portion of toilet relocation: $1,800-3,500
- Slab coring (sometimes a separate concrete contractor): $300-700 if not included in plumbing quote
- Tile and waterproofing reinstatement to affected areas: $500-1,500
- Total additional cost vs not moving the toilet: $2,600-5,700
When toilet relocation is worth it
- Original layout is awkward or dated. Toilet in the middle of the room when it should be tucked into a corner. Toilet right in the line of sight from the door.
- You want a bigger vanity or longer bench and the toilet currently sits in that space.
- You are adding a wall-hung toilet which often needs different in-wall plumbing position.
- You are converting to a powder room or ensuite with a different room layout.
- The existing position causes constant cleaning or use issues.
When toilet relocation is NOT worth it
- The current position is fine and you are just looking at it differently. Sometimes a new toilet (different style, wall-hung or back-to-wall) in the same position transforms the look without the relocation cost.
- Budget is tight and the $2,600-5,700 could go to better tapware, joinery or tile.
- The new proposed position has structural or drainage constraints that complicate the relocation significantly.
Drainage fall, the technical constraint
The drain from the new toilet position to the sewer line must run downhill at a minimum fall of 1:60 (rises 1mm per 60mm of horizontal run). Steeper is fine. Less than 1:60 is below code and risks slow flushing, blockages, and gurgling.
If the new toilet position is far from the sewer line OR the sewer line runs at a high elevation under the slab, achieving 1:60 fall can be difficult. In rare cases the slab needs significant trenching or a small step-down to accommodate. We assess at quote stage.
Moving the shower or basin instead
Same considerations apply but with slightly less stringent drainage requirements. Basin drainage can use smaller pipe with less critical fall. Shower drainage needs proper fall but the floor waste can be positioned to suit. Costs are similar to toilet relocation, $1,800-3,500 typical for the plumbing portion.
Two-storey homes
Upstairs bathrooms in two-storey homes have drainage running through the floor cavity rather than through a slab. Relocation is sometimes easier (no slab coring) but sometimes harder (less room to run new drainage at proper fall within the floor depth). Assessment on-site.
Apartments
Apartment bathrooms typically connect to a vertical sewer stack that runs through the building. Moving the toilet within the lot is possible but the new position cannot be too far from the existing stack connection point without significant in-floor drainage modification. Some apartments have restrictions in strata bylaws on stack-modifying work. We check at quote stage.
What to plan
- Decide layout before quote stage. Position changes during the reno are very expensive.
- Ask for the full layout-change scope at quote stage, including tile and waterproofing reinstatement. Plumber-only quotes can understate the total cost.
- Consider whether wall-hung toilet (in-wall cistern) is an option, it needs a thicker wall but enables a sleeker look.
- Plan for the right toilet model at the same time, back-to-wall, wall-hung, traditional close-coupled all have different drainage and fitting requirements.
The maximum distance from the existing stack
Every toilet relocation has a practical upper limit on how far you can move it from the existing sewer connection point. The constraint is drainage fall, you need 1:60 minimum (1mm of drop per 60mm of horizontal run) per AS3500. For typical slab-on-ground Gold Coast homes:
- Up to 2m from existing stack: easy, standard relocation, no fall issues. $1,800-2,800 plumbing portion.
- 2-4m from existing stack: achievable in most cases. Fall calculation tighter, sometimes requires the new slab penetration to be slightly recessed. $2,400-3,500.
- 4-6m from existing stack: challenging on slab homes. Fall requirement means the drain runs 70-100mm deeper at the connection end, sometimes hits the structural beam. $3,200-4,800 plus possible structural assessment.
- 6m+ from existing stack: rarely worth doing. Cost typically exceeds $5,000, often requires step-down in floor or external relocation of the stack itself.
If your desired position is more than 4m from the existing toilet, get the slab depth and stack location surveyed before committing to the new layout. We can do this in a 1-hour site visit, $180-280, and you avoid a surprise at quote stage.
Wall-hung toilets and the in-wall cistern question
Wall-hung toilets (Geberit, Caroma Cube Invisi, Roca In-Wall) have surged in popularity on the Gold Coast over the last 5 years and they change the relocation conversation. Differences from a standard close-coupled toilet:
- In-wall cistern frame: the cistern sits inside the wall behind tiles. Requires 200-250mm wall depth, sometimes a thickened wall built specifically.
- Wall-mounted pan: bolts to the in-wall frame, no floor contact. Slab penetration sits behind the wall rather than centred under the pan.
- Service access via flush plate: all cistern serviceability is via the chrome or brass flush plate on the wall. If a fault develops, the flush plate comes off and the cistern is accessed.
- Cost: $1,200-3,800 for a quality in-wall system (Geberit Sigma 8 plus pan) versus $400-900 for a standard close-coupled. Plus framing carpenter time to build the supporting wall.
The aesthetic gain is real (much sleeker line, easier floor cleaning, more visual space). The serviceability tradeoff is also real (every internal repair needs the flush plate off and an arm into the wall cavity). For most owners, the gain wins. For owners who want zero future hassle, a standard floor-mounted back-to-wall is the safer pick.
Two-storey homes, the upstairs constraint
Second-storey bathrooms in two-storey Gold Coast homes (common in Helensvale, Pacific Pines, Robina townhouses) have different relocation rules. The drainage runs through the floor cavity (typically 200-300mm depth) rather than through a slab. Implications:
- Easier in some ways: no slab coring required. Floor cavity can be accessed by lifting flooring above or ceiling below.
- Harder in other ways: floor depth limits how much fall you can build into the run. Long relocations may not achieve 1:60 fall within the cavity.
- Ceiling damage below: if access is from below, the downstairs ceiling needs cutting and patching. Add $400-900 for plasterer return and painting.
- Engineering check sometimes required: cutting a new opening through a structural floor joist needs engineer sign-off, $400-700.
Typical upstairs toilet relocation cost runs $2,200-4,200 including ceiling patching, slightly more than ground-floor on slab.
The sewer stack itself, can it move
The vertical sewer stack (the main pipe running from your bathroom drainage down through the slab to the council sewer connection) is rarely moved because the cost is high and the disruption significant. In some scenarios it makes sense, complete bathroom relocation to a different room, full-floor renovation, conversion of a non-bathroom space into a bathroom. Cost for stack relocation including external excavation, new connection to council main, slab repairs, $4,500-12,000 typical. We get an engineer involved and council approval is sometimes required if the connection point on the main shifts. Worth doing if the rest of the renovation hinges on it, expensive overkill for a simple bathroom refresh.
Apartment toilet relocations and stack constraints
Apartment bathrooms in Surfers, Broadbeach, Main Beach and similar towers connect to a vertical sewer stack that serves the whole column of bathrooms above and below. This stack is body corp common property and cannot be modified by an individual lot owner. Constraints that follow:
- The new toilet position must be within reach of the existing stack connection point on your lot. Typically 1.5-3m maximum from the existing stack on most apartment plans.
- Stack penetration points cannot be added or moved without body corp approval and engineering certification. Most body corps will not approve.
- Some buildings have stack maps in the body corp records. Worth getting these before designing the new layout.
- Floor depth for in-floor drainage is limited. Most apartments have only 100-150mm of floor cavity between slab and floor finish, less than a freestanding house.
The practical result is apartment toilet relocations are constrained to small position shifts (rotating from front-facing to side-facing, moving 500mm-1500mm) rather than full layout changes. Owners planning major apartment bathroom redesigns need to work with the stack location as a fixed point.
The drainage venting question
An often-missed element of toilet relocation is drainage venting. Every fixture drain needs a vent connection that prevents siphoning of the water trap. In a new toilet location, the existing vent may not reach the new drain run, requiring either a new vent through the roof or an air admittance valve (AAV) installed in the wall.
Vent through the roof, $400-900 to install. AAVs, $80-180 each. Most modern installs use AAVs because they avoid roof penetration and waterproofing risks. Both are compliant per AS3500. The difference matters if your local council has specific requirements or your reno designer prefers one over the other. We discuss this at quote stage.
What the council expects on toilet moves
Toilet relocation within an existing bathroom does not require council approval on the Gold Coast as long as the work is done by a licensed plumber and certified with a QBCC Form 4 (Notification of Work) lodged on completion. We handle this paperwork as standard, you do not need to deal with council directly.
The exception is if the toilet move is part of a larger bathroom layout change that affects waterproofing or structural elements, in which case additional building work approval may be needed. Most simple toilet relocations within an existing bathroom are below this threshold and proceed without further approval. We flag any approval requirements at quote stage so there are no surprises.