Plumbing on a new build happens in stages. Knowing them helps you ask the right questions.

Under slab

Before the slab is poured, drains and water lines go in the ground. Mistakes here are expensive to fix later.

Rough in

After the frame goes up, pipes run through walls and ceilings.

Fit off

After finishing, fixtures and appliances are installed and tested.

Hot water choice

Decide early between gas, electric, heat pump or solar.

Compliance

Plumbing must meet the rules and sign-off is required. Keep your certificates.

Extras to consider

Rainwater tanks, outdoor taps, gas points and filters are easiest to add during the build.

Talk to us

We can quote new home plumbing and work with your builder.

Reading the plumbing plan

Ask for the plumbing plan and check where taps, toilets, showers, laundry, hot water and outdoor taps sit. Make sure the positions suit your furniture and appliances. It is much easier to move a pipe on paper than in a finished wall.

Choosing a hot water system

Gas, electric, heat pump and solar all have different costs and running costs. Think about your gas connection, your roof, and how many people live in the house. We can explain the differences without pushing one type.

Stormwater and drainage

The site needs a plan to carry stormwater away from the house and off the block. Pits, pipes and connections need to be set at the right levels. Mistakes lead to flooded yards later.

Final inspection and handover

Before you take possession, test every tap and toilet. Run the shower. Check the hot water. Ask for certificates and warranty details for fixtures and the hot water system. Keep them somewhere safe.

Plan for the future

If you might add a rainwater tank, a granny flat or an outdoor kitchen later, ask the plumber to leave capped connections. It costs little now and saves digging up the yard.

What owners should check on the plumbing plan

Most owners never read the plumbing plan, and then find out at handover that there is only one outdoor tap or no point for a washing machine in the right spot. Ask your builder for the plumbing layout before slab and framing. Check the number and position of taps, the hot water unit location, floor wastes, the laundry and any gas points.

If you want a rainwater tank, a filtered water tap, an outdoor shower or a second laundry tap, say so before rough in. These are cheap to include at that stage and expensive to add after walls are lined and the concrete is poured.

Handover day checks

Before you accept the house, run every tap, flush every toilet and run the shower. Check that hot water arrives at every hot tap in a reasonable time. Look under every sink for drips. Ask for the compliance certificates and any manuals and warranty details, and keep them somewhere safe.

Know where the water mains valve, hot water isolation valve and gas meter are. If something is wrong, tell the builder in writing straight away. Most builders have a defects process and a defects period, so check yours and use it.

Questions to put to your builder in writing

Who is the plumber, and are they licensed? What fixtures and tapware are included, and what are the allowances? Where are the hot water unit, outdoor taps and gas points? When are the plumbing stages and inspections? Who issues the compliance paperwork? What is the defects process and how long is the defects period?

Ask for the answers by email so you have a record. If a variation is needed, ask for the price in writing before the work is done.

Questions for your builder

Which plumber is doing the work? Is the hot water system included? What fixtures are in the price? What warranty applies? Get the answers in writing.

Stage one: before the slab

Everything under the concrete is done first. The plumber lays sewer drains, stormwater lines and often the water supply pipes, set out from the building plan. Drain levels have to be right, because once the slab goes down, mistakes mean breaking concrete. The drains are usually tested and inspected before the pour. If you are building, ask that photos be taken of the pipework before the slab covers it. They are useful records for the future.

Stage two: frame and rough in

Once the frame is up, the plumber returns to run pipes through walls and ceilings, set shower and bath positions, and prepare for the laundry and kitchen. Hot water systems are positioned and gas lines are roughed in. This is the time to confirm where taps, outdoor points and appliances will sit. Decisions made here, such as a pot filler tap or a second laundry tap, are easy now and costly later.

Roof plumbing, which includes gutters, downpipes and flashings, is usually done at this point. Check that downpipes go where you expect and that stormwater connects properly.

Stage three: fit off and handover

After the walls are lined, tiled and painted, the plumber fits taps, toilets, basins, the shower screen waste and connects appliances. They turn on the water and gas, test each outlet, check for leaks and bring the hot water system into service. You should have a walk-through where every tap and toilet is run.

At handover, get the certificate of compliance for the plumbing work, warranty information for fixtures and the hot water system, and the manuals. Take note of where the main water tap and gas shutoff are.

Common mistakes to avoid

Not choosing fixtures early enough, so the plumber cannot plan for them. Leaving out outdoor taps and then adding them after the landscaping. Choosing a hot water system that is too small for the family. Skipping extra points for a future rainwater tank. Forgetting to ask about gas capacity when planning a cooktop, heater and hot water system together. A short chat with a plumber at design stage avoids these.

How we can help

We work with owner builders, builders and homeowners on new home plumbing across Geelong and Melbourne. Send us your plans and we can talk through your options and the stages, then quote the work in writing.

More to read:

Where we work: Geelong, Melbourne CBD, Werribee and the full list of service areas.

Talk to GSA Plumbing Services

We work across Geelong and Melbourne, 24 hours a day, 7 days a week. Call 0401 041 103 or use the contact page. Quotes are free and there is no call-out fee.