Bidets are becoming increasingly popular in Australian bathrooms. Travellers return from Japan wondering why every toilet does not have one. Smart toilet seats are appearing in major retail stores, while inexpensive handheld sprays and attachments are readily available online.
But a growing public discussion is exposing an uncomfortable question:
How many bidets in Australian homes have been installed illegally?
There is no reliable national figure. However, recent online discussions are filled with homeowners admitting they installed their own bidet in ten minutes, assumed a product sold by a major retailer must be legal to install, or had never heard of backflow prevention.
That suggests Australia may have accumulated a significant hidden stock of non-compliant bidets.
Bidets Have Not Suddenly Been Banned
Let’s clear up the biggest misconception first.
Bidets are not illegal in Australia.
What is illegal is connecting a bidet product to the drinking water supply without complying with Australian plumbing requirements. In Queensland, that normally means the installation must be completed by a licensed plumber, use appropriately WaterMark-certified products and include the correct protection against backflow.
The rules are not new. What is changing is public awareness of them.
The Australian Competition and Consumer Commission warned during the 2020 toilet paper shortage that DIY bidet installations could expose households and neighbouring properties to contaminated drinking water. Six years later, many Australians are only now learning that the warning applies to the inexpensive attachment already connected to their toilet.
The Retail Shelf Creates a Dangerous Assumption
One reason for the confusion is simple: people assume that if they can legally purchase a product, they can legally install it themselves.
That is not how regulated plumbing products work.
A bidet seat might be available from a hardware retailer. A handheld spray might arrive with a tee fitting, flexible hose and instructions describing a quick DIY installation. None of that overrides Queensland plumbing law.
The ACCC’s product safety guidance specifically states that suppliers must not make false or misleading claims about bidet products being suitable for DIY installation. Products connected to the drinking water supply must be installed by a licensed plumber.
WaterMark certification is also essential, but certification of the product does not authorise the homeowner to install it.
A compliant product can still become a non-compliant installation.
Why Does a Small Toilet Hose Create a High-Hazard Risk?
The issue is not the normal direction of the water. It is what can happen when water pressure suddenly drops.
Imagine a handheld bidet spray has been dropped into the toilet bowl. If the water main is damaged, firefighters draw heavily from the network or the supply is temporarily interrupted, the pressure inside the pipes can fall.
Without appropriate backflow protection, contaminated toilet water may be drawn backwards through the spray and into the drinking water system.
That contamination may not necessarily remain inside one bathroom. Depending on the plumbing system and the circumstances, it can potentially affect other outlets within the property or the wider supply.
This is why handheld bidet hoses and trigger sprays are treated as high-hazard cross-connections under Australian plumbing requirements. A cheap check valve intended for a garden tap is not automatically suitable protection for a high-hazard toilet connection.
Handheld Sprays and Bidet Seats Are Not the Same
This is where many explanations become misleading.
A handheld spray beside the toilet is capable of being dropped into the bowl. It therefore requires appropriate high-hazard backflow protection, typically involving a testable device such as a Reduced Pressure Zone Device.
A toilet-mounted bidet seat may be different.
Some WaterMark-certified bidet seats contain approved integral protection, such as an air gap or Atmospheric Vacuum Breaker. If that protection is properly certified for the product and the installation complies with the relevant requirements, an additional external RPZ device may not be necessary.
Other seats do not have adequate integral protection and must be protected externally.
The answer cannot be determined from the appearance of the seat or a claim that it has a “backflow valve”. The product’s exact WaterMark certification and installation configuration need to be checked.
What Makes a Bidet Installation Compliant in Queensland?
A compliant installation generally involves several separate requirements:
1. A licensed plumber completes the connection
Connecting the product to the toilet’s drinking water supply is regulated plumbing work. It is not made legal by the connection being simple or inexpensive.
2. The product is WaterMark certified
The exact model and its certification details should be verified through the WaterMark Product Database. A logo shown on an overseas website is not enough.
3. The correct backflow protection is installed
This might be approved protection built into a compliant bidet seat or a separate high-hazard backflow device. Handheld sprays ordinarily require external high-hazard protection because the nozzle can reach the toilet bowl.
4. The work is registered
Plumbing work of this kind in an existing Queensland home is generally treated as notifiable work. The plumber must register the work with the QBCC using a Form 4 and provide the relevant party with a copy.
The QBCC also advises that it and local governments conduct audits of notifiable plumbing work.
5. Testable devices are registered and maintained
If an external testable backflow device such as an RPZ valve is installed, it must be registered with the relevant local council and tested by an appropriately endorsed plumber at least once every 12 months.
This annual requirement does not automatically apply to every bidet. A properly certified integral air gap or non-testable device is treated differently from an external testable RPZ valve.
“Mine Has Worked for Years” Does Not Prove It Is Safe
Backflow protection is designed for abnormal events.
A non-compliant bidet can appear to work perfectly for years because the household has not yet experienced the combination of a contaminated outlet, open pathway and significant pressure drop required to cause back-siphonage.
That is similar to saying an electrical circuit must be safe because it has not started a fire. The absence of an incident is not evidence that the protection is adequate.
There is also a separate flooding risk. Cheap fittings, unsuitable flexible hoses and excessive water pressure can fail and release water continuously into the bathroom.
Already Have a Bidet? Here Is What to Check
If a bidet seat, handheld hose or trigger spray is already connected beside your toilet, ask:
- Was it installed by a licensed plumber?
- Can you verify the exact product in the WaterMark database?
- Does its WaterMark description identify approved integral high-hazard protection?
- Was a QBCC Form 4 issued for the installation?
- If an external RPZ device was installed, is it registered and tested annually?
- Has the property’s water pressure been checked against the product’s maximum operating pressure?
If you cannot answer those questions, it does not necessarily mean the entire bathroom needs to be rebuilt. It means the installation should be assessed properly.
Do not attempt to make it compliant by adding a generic valve yourself. Backflow devices have different hazard ratings, and selecting or installing the wrong device may provide little more than false confidence.
The Real Bidet Story in 2026
The story is not that Australia has suddenly outlawed bidets.
It is that bidet adoption has moved faster than consumer understanding of the plumbing system behind them. Products that look like simple bathroom accessories are being connected directly to the drinking water supply, often by people who have never been told that the connection is regulated.
For homeowners, the solution is straightforward: choose an approved product, have the installation assessed or completed by a licensed plumber and make sure the required compliance record exists.
RJT Plumbing & Gas can inspect an existing bidet installation, check its certification and backflow protection, or help you choose and install a compliant system from the beginning.
If you are unsure whether the bidet beside your toilet is legal, it is better to find out from a plumber than from a future plumbing audit, water leak or contamination event.
Frequently Asked Questions
Are bidets illegal in Australia?
No. Bidets are legal in Australia, but products connected to the drinking water supply must comply with Australian plumbing requirements. They must use appropriately WaterMark-certified products, include suitable backflow protection and be installed by a licensed plumber.
Can I install my own bidet in Queensland?
No. Connecting a bidet seat, handheld bidet spray or similar product to the drinking water supply is regulated plumbing work. The connection must be completed by an appropriately licensed plumber.
Why do bidets require backflow protection?
Backflow protection prevents contaminated water from being drawn backwards into the drinking water system during a loss or change in water pressure. A handheld spray or bidet outlet near the toilet can create a high-hazard cross-connection if suitable protection is not installed.
Does every bidet require an external RPZ valve?
Not necessarily. Some WaterMark-certified bidet seats contain approved integral high-hazard protection, such as an air gap or Atmospheric Vacuum Breaker. If adequate protection is not built into the product, an external high-hazard device such as a Reduced Pressure Zone Device may be required. Handheld sprays ordinarily require external high-hazard protection.
What does WaterMark certification mean for a bidet?
WaterMark certification confirms that a plumbing product has been assessed against the applicable Australian product requirements and is authorised for use in plumbing installations. Certification should be verified for the exact model through the official WaterMark Product Database.
Does a bidet installation require a QBCC Form 4?
Installing a bidet in an existing Queensland home will generally involve notifiable plumbing work. The licensed plumber undertaking the work must register it with the QBCC and provide the relevant party with a copy of the Form 4 notice.
Do bidet backflow devices require annual testing?
External testable backflow devices, such as RPZ valves, must be registered with the relevant local council and tested by an appropriately endorsed plumber at least once every 12 months. Approved integral non-testable protection built into a bidet seat is treated differently and does not normally require annual testing.
How can I check whether my existing bidet is compliant?
Ask a licensed plumber to verify the product's WaterMark certification, inspect the water connection, identify the installed backflow protection and confirm whether a Form 4 or annual testing requirements apply. Do not assume that a generic backflow valve makes the installation compliant.
