Back-flow Prevention Valve ?

Your licensed plumber will know the regulations and what to do.

You are apparently intending to do ILLEGAL DIY plumbing work!

Here are the facts:

What you are (apparently) intending to (wrongly and illegally) do is regulated plumbing work that must be done by a registered plumber who is licensed to perform that class of work.

The three classes of backflow risk are low, medium or high as per AS/NZS 3500.1

Bidets are rated as high risk and require a RPZ valve. These differ from the normal dual check valves (DC) in that they discharge any backflow to atmosphere via a relief valve if both check valves fail. DCs don't do this.

There is no way of knowing whether a DC has failed.

BUNNINGS:

It is bad enough that Bunnings sell products that are not compliant once fitted (I am not referring to the Kinetic "Backflow Preventer" here when used as per the regulations) but it is even worse when a Bunnings employee recommends a product (Kinetic "Backflow Preventer") that doesn't comply with a critical plumbing regulation when fitted for Joe Public's stated intended use.

Bunnings even allows illegal online advice (see link below) from their team and unknown Joe Publics that remain uncorrected or undeleted. One such example about a bidet connection is below. A plumbing company later posted the facts with regulatory references (I suggest you read their post), only to be then asked a moronic question from the "Bunning's resident DIY expert" about using the Kinetic Back Flow Preventer.....which the plumbing company never dignified with an answer.

https://www.workshop.bunnings.com.au/t5 ... td-p/66417

As per what I originally posted, "Your licensed plumber will know the regulations and what to do."

A RPZ valve is larger than a standard DC valve due to it having the backflow discharge facility. A RPZ valve is also mandated to have annual inspections.

Maybe you could be inventive by having a recessed wall storage space (or two for aesthetics) that could be pulled out when required to check the RPZ. You would only need an enclosed 'box' that slid into an open frame.

If you have a bidet seat that has a minimum 25mm air gap, you do not need a RPZ valve. The Fair Trading (NSW) doc below is worth reading.

https://www.fairtrading.nsw.gov.au/trad ... ow-control

There is a lot of ongoing concern in the industry about illegal bidet installations. I am in Vic and I will link a VBA media release below but ones from other States are easy to find.

https://www.vba.vic.gov.au/__data/asset ... evices.pdf

I can't recommend anything, sorry, because I have nothing to do with bidets apart from advising people I talk to that their bidet isn't compliant when I see they have rainwater connected. Most of the time, those installations are also DIY and don't have a RPZ or even a DC at times.

There are specialised bathroom showrooms that should be able to help you. Using Google and appropriate keywords should also fast track your search results.

I clicked on the Bunnings link and read the first review which stated in part:
To be watermark compliant, you need a backstop valve, a la this Kinetic one. It's not included, but you should have it even if you aren't getting a plumber to do the installation. https://www.bunnings.com.au/kinetic-chr ... r_p4920512 -

It's a worry!