Installing a bidet in Australia is straightforward to arrange — but it is not a DIY job. Because a bidet connects to your drinking-water supply, there are real plumbing rules designed to protect your household's water. This guide explains exactly how bidet installation works, the standards involved, what to expect on the day, and what it costs — so you can plan with confidence.
First, the Golden Rule: Use a Licensed Plumber
DIY plumbed-in bidet installation is illegal in Australia
Connecting any bidet — seat, attachment, handspray or smart toilet — to the water supply is licensed plumbing work. Doing it yourself can contaminate your drinking water, void your home insurance, and result in fines. A licensed plumber also issues a compliance certificate, your legal proof the job was done to standard.
This rule applies to every bidet type that connects to the water supply: electric bidet seats, cold-water seats, handheld sprayers, and complete smart toilet suites. The only exception is a self-contained portable bidet that is filled from a tap and has no plumbing connection — those need no plumber at all.
Why Bidets Are Treated as a Backflow Hazard
A bidet's washing outlet sits close to the toilet — an area that can become contaminated. Without protection, a sudden drop in mains pressure could create a siphon effect that draws that water back into the clean supply, contaminating it.
What Backflow Is (in Plain English)
Backflow is water flowing the wrong way — backwards from a fixture into the drinking-water pipes. Every bidet with a water connection is classed as a cross-connection hazard for this reason, which is why a backflow-prevention device is central to every compliant installation.
This Is Why Compliance Exists
Backflow is not theoretical — during water-main repairs, firefighting, or pressure fluctuations, reverse siphonage can and does happen. The standards exist to protect your household and the wider water network. A certified backflow device is your safeguard.
The Standards Your Install Must Meet
Four requirements apply to every plumbed bidet installation in Australia.
WaterMark
WaterMark Certification
Every bidet connected to the water supply must carry a WaterMark mark — proof it meets Australian plumbing product requirements. It is illegal to install a non-certified bidet. The Bidet Shop's range is certified to WMTS-051 (Lic. No. 20094).
AS/NZS 3500.1
Water Services Standard
Clause 12.2.3 specifically covers bidets and douches — specifying connection requirements, hazard classification, and the backflow protection needed based on the outlet's position relative to the toilet pan.
NCC Volume 3
National Construction Code
The Plumbing Code of Australia (NCC Volume Three) mandates backflow protection for all bidet installations. The Bidet Shop's products carry this warning directly: the installation "must include appropriate backflow protection conforming to the NCC – Volume 3."
AS/NZS 2845.1
Backflow Prevention Devices
Specifies the requirements for backflow prevention devices themselves — types, installation, and testing. High- and medium-hazard devices must be tested annually by a licensed plumber and a certificate issued each time.
High-Hazard vs Low-Hazard: The 25mm Rule
Not all bidet installations require the same level of backflow protection. Your licensed plumber determines the hazard rating on site based on one key measurement.
Outlet within 25mm of pan overflow level
Applies to most handheld sprayers, many bidet seats, and any install where the nozzle can reach into or near the toilet bowl.
Requires: Reduced Pressure Zone (RPZ) valve or registered air gap — plus annual testing
Outlet stays 25mm+ above pan overflow level
Applies to bidet installations where the outlet is fixed high enough that it cannot reach the contaminated zone of the bowl.
Requires: Appropriate lower-hazard backflow device — as determined by licensed plumber
Annual Testing of Backflow Devices
High- and medium-hazard backflow devices must be tested by a licensed plumber when first installed and then once a year thereafter to confirm they are still functioning correctly. Keep the annual certificates — they may be required by your insurer or local water authority.
What the Installation Process Looks Like
A standard bidet installation by a licensed plumber follows these four stages. Most straightforward seat or sprayer jobs can be completed in a single visit.
Isolate the Water Supply
The plumber turns off and isolates the toilet's water supply, then drains the line so the connection can be made safely and without leaks during fitting.
Fit the T-Valve & Backflow Protection
A T-valve taps into the supply line feeding the cistern, and the appropriate backflow-prevention device is fitted to the hazard rating the plumber has determined. If mains pressure is high, a Pressure Reducing Valve (350 kPa) may also be added to protect the fittings and improve comfort.
Mount the Bidet & Connect Power (if electric)
The bidet seat, attachment, sprayer or smart toilet is mounted to the toilet and connected to the water line. For electric models, the unit is plugged into a nearby power point — one that is on an RCD-protected circuit. If no power point exists beside the toilet, a licensed electrician must add one before this step.
Test, Certify & Commission
The plumber checks all connections for leaks, tests the backflow device to confirm it is working correctly, verifies the bidet operates as expected, and issues a compliance certificate. Keep this certificate — it is your legal proof of a compliant installation and may be required for insurance or future property sales.
Do You Need a Power Point? (Electric Bidets)
Electric bidets need a dedicated, RCD-protected power point
Electric bidet seats and smart toilets require a power point beside the toilet on a circuit protected by a safety switch (RCD), in line with AS/NZS 3000. Many Australian bathrooms — particularly older ones — do not have a power point near the toilet, so factor in a licensed electrician to install one. Like the plumbing work, adding or altering a power point is not a DIY task. Your plumber and electrician can often coordinate to complete both jobs in a single visit.
Renting? Here's How Bidet Installation Works
🏠 Renters Can Absolutely Have a Bidet
- Choose a bidet model that removes cleanly — a seat or attachment, not a built-in smart toilet suite that requires major plumbing works.
- Get your landlord's written permission before booking any trades (most landlords are fine with a reversible seat install).
- Have a licensed plumber install it — the same rules apply in a rental as in an owner-occupied home.
- When you move out, a plumber can remove the bidet and restore the original fittings, leaving the bathroom exactly as found.
- Keep your compliance certificate — it protects you if there is ever a dispute about the installation.
How Much Does Bidet Installation Cost?
The total cost depends on the bidet type, the hazard rating of your installation, and whether electrical work is needed. Here is a general guide to the components involved:
| Cost Component | Notes |
|---|---|
| Bidet unit / kit | From $98 (handspray) to $5,290+ (smart toilet suite) — check live product pages |
| Licensed plumber — labour | Varies by location, job complexity and time on site |
| Backflow device | Low-hazard devices are modest; high-hazard RPZ valves cost more — plumber supplies |
| Annual backflow testing | Ongoing requirement for high- and medium-hazard devices; varies by plumber |
| Pressure Reducing Valve (optional) | ~$48 from The Bidet Shop — recommended for high-pressure areas |
| Licensed electrician (if needed) | Required if no RCD-protected power point is near the toilet |
Get It Done Once, Done Right
A compliant installation by The Bidet Shop's team covers the bidet, backflow device, compliance certificate and any pressure management needed — so there are no surprise call-backs or compliance gaps. See the installation page for details.
Frequently Asked Questions
No — not if it connects to your water supply. Plumbed-in bidet installation is licensed plumbing work in Australia; doing it yourself is illegal, can contaminate your drinking water, and may void your home insurance. The only exception is a portable, self-contained bottle bidet that you fill from a tap and has no plumbing connection — those require no trades at all.
Every plumbed bidet requires backflow protection appropriate to its hazard rating. High-hazard installations — where the outlet can reach within 25mm of the pan overflow level, as with most handheld sprayers and many seats — require a high-hazard device such as an RPZ valve, plus annual testing. Lower-hazard installs require a less complex device. Your licensed plumber assesses this on site and fits what is required.
A standard seat or handspray installation — where a power point already exists and the backflow assessment is straightforward — is typically a quick single visit. Jobs that involve fitting a high-hazard RPZ valve, adding a power point, or installing a complete smart toilet suite take longer. Your plumber and, if needed, electrician can give you a realistic time estimate when they assess your bathroom.
The Bottom Line
Bidet installation in Australia is simple to arrange but must be done right: a licensed plumber, the correct backflow protection for your hazard rating, a WaterMark-certified product, and a compliance certificate at the end. Get those in place and you have a safe, legal installation that protects your water, your insurance, and your household. The Bidet Shop sells WaterMark-certified products across every budget and runs its own factory-certified install team. Start here or call 1300 243 387 for a quote tailored to your bathroom.
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Browse All BidetsAbout The Bidet Shop — Australia's largest bidet specialist, with retail stores, a warehouse and a factory-certified repair and installation team. All plumbed products WaterMark certified to WMTS-051 (Lic. No. 20094). DIY plumbed-in bidet installation is illegal in Australia — always use a licensed plumber.