Yes, bidets are legal in Australia. However, all bidets must be certified to meet Australian standards. OTR (Office of the Technical Regulator) states that “all bidets must be installed in conjunction with a toilet seat and flexible hoses installed adjacent to the toilet are required to have RPZs fitted”.
A little unsure as to what that means? Well, an RPZ (reduced pressure zone) is a device that prevents backflow and water contamination. It must be installed before the water is connected, and so a licensed plumber should be the one to do so.