Backflow Prevention For Bidet

[80's Owl]

I've been told by a local authority that we need to fit backflow prevention to a bidet which I've not a problem with but just need to know exactly what I need to fit as there seems to be an array of options, it's classed as a Cat 5 fluid.

[SteamyTea]

I have just googled this.

Seems that the hot and cold pipes can sometimes suck back the fluids.

 

I would post up some pictures, but the kiddy filter at work has kicked in.