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Of all the trades involved in a kitchen renovation, plumbing is the one that has to happen at exactly the right point in the process, not too early, not too late. Get the sequencing wrong and you end up with a beautiful new benchtop sitting over a drain that's in the wrong place, or a cabinetmaker building around a water line nobody told them about.
Before you lock in your kitchen design, it's worth working through the plumbing decisions first. Most of them affect layout, cabinetry, and even electrical planning, so they need to be settled early, not fitted in around everything else at the last minute.
1. Decide Early Whether the Sink Is Moving
This is the single biggest plumbing decision in any kitchen renovation, because it affects almost everything else.
Keeping the sink in the same spot
is the cheapest and simplest option. Existing water supply and drain lines can usually be reused with minor adjustments, keeping both cost and disruption low.
Relocating the sink
to an island, a different wall, or simply a few hundred millimetres away from its current spot means running new supply lines and, more significantly, a new drain connection with the correct fall (slope) to the existing sewer line. This is entirely doable, but it needs to be confirmed by a plumber before cabinetry is finalised, since the new drain run has to fit within the floor or wall cavity available.
2. Plan Your Dishwasher Connection Point
If you're installing a dishwasher for the first time, or moving it to a new cabinet, it needs its own hot and cold water connections plus a drain line, usually run to tie in near the sink's plumbing. This is a straightforward addition when planned early, but expensive and messy to retrofit after cabinetry and flooring are in.
If you're not sure exactly how a dishwasher connects in, our guide on how to connect a dishwasher to plumbing covers the supply, drain, and air gap requirements in detail.
3. Confirm Your Water Supply Capacity
Adding fixtures, like a second sink, a filtered water tap, an instant boiling water unit, or an ice-making fridge, adds demand to your existing water supply lines. In older homes with narrower original pipework, this can mean pressure drops when multiple fixtures run at once.
Have a plumber assess your existing supply line size before finalising which fixtures you want. It's far cheaper to upsize a supply line during a renovation, while walls are already open, than to discover a pressure problem after everything is tiled and sealed.
4. Check Your Drain Line Capacity and Fall
Every drain needs the correct fall, a slight downward slope, to move wastewater away efficiently. If you're relocating the sink or adding a second one, your plumber needs to confirm there's enough floor or wall cavity depth available to achieve the required fall to your existing sewer connection point.
This is a common point where renovation plans hit a snag: a beautiful island sink design that simply can't achieve the fall it needs without raising the floor or running the drain a long, indirect route. Getting this checked at the design stage avoids an expensive redesign mid-renovation.
5. Think About Hot Water Delivery Time
If your kitchen is a long way from your hot water system, you may already notice a wait for hot water to arrive at the tap. A renovation is the ideal time to address this, either by relocating fixtures closer to the hot water system, insulating hot water lines, or installing a small instantaneous hot water unit under the new sink for immediate hot water without the wait.
6. Plan for a Water Filtration or Boiling Water Tap
If you want a filtered water tap, an instant boiling water tap, or a combination unit, these need their own dedicated supply line, and boiling water units also need a power connection nearby. Deciding on this before cabinetry and benchtop templating means the tap hole and under-sink space are planned in from the start, rather than an awkward retrofit.
7. Confirm Gas Line Requirements If You're Changing Cooktops
Switching to or from a gas cooktop, or moving its location, involves gas line work that must be carried out by a licensed gas fitter. This needs to be finalised before benchtop templating, since the gas point location is fixed into the design.
8. Don't Forget the Fridge Water Line
If your new fridge has a water and ice dispenser, it needs a dedicated water line run to its location, ideally concealed within the cabinetry rather than run externally. This is a small, inexpensive addition when planned with the rest of the kitchen plumbing, and an annoying afterthought if it's missed.
A Simple Pre-Renovation Checklist
Before you finalise your kitchen design, confirm each of these with a plumber:
- Is the sink staying in place, or relocating?
- Does the new drain layout have enough fall to the sewer connection?
- Is your existing water supply line large enough for any new fixtures?
- Where exactly does the dishwasher connect, and is that point accessible in the new layout?
- Do you want a filtered or boiling water tap, and where's the power point for it?
- Is the fridge water line planned into the cabinetry?
- Are you changing your cooktop, and does that need new gas work?
- Is the hot water delivery time to the kitchen acceptable, or worth addressing now?
Get Your Plumbing Locked In Before Cabinetry Is Ordered
The costliest mistakes in a kitchen renovation almost always come from plumbing decisions made too late, after cabinetry has already been ordered to a fixed layout. A short consultation with a plumber at the design stage can confirm what's easily achievable and what needs a workaround, before you're committed to a floor plan.
Coastal Plumbing Professionals works with Gold Coast homeowners and renovators to plan and install kitchen plumbing correctly the first time, from sink relocations to dishwasher and filtered water connections.
Call 1300 590 085 to arrange a plumbing consultation for your renovation.
Frequently Asked Questions
How early should I involve a plumber in a kitchen renovation?
Before you finalise your kitchen design or order cabinetry. Plumbing decisions, particularly sink location and drain fall, directly affect what layouts are practical, so it's far cheaper to confirm this early than to redesign around a plumbing constraint later.
Can I move my kitchen sink to a different wall?
Usually yes, but it depends on whether a new drain run can achieve the correct fall to your existing sewer connection within the available floor or wall cavity. A plumber needs to assess this before the layout is finalised.
Does a dishwasher need its own water line?
Yes, a dishwasher needs a dedicated hot and cold water supply connection and its own drain line, typically tied in near the sink's existing plumbing.
How much does kitchen renovation plumbing typically involve?
This varies significantly depending on whether you're keeping fixtures in their existing locations or relocating them, and how many new fixtures (dishwasher, filtered tap, second sink) you're adding. A plumber can scope this accurately once your design is close to final.
Do I need a licensed plumber for kitchen renovation work?
Yes. All plumbing and gas fitting work in Queensland must be carried out by a licensed plumber or gas fitter, both for compliance and to ensure the work is covered by statutory warranty.
Resources
- Plumbing and Drainage Act 2018 | Queensland Government
- AS/NZS 3500 Plumbing and Drainage Standards | Standards Australia
- Queensland Building and Construction Commission (QBCC)
