I'm building a house and wanted to fit a bidet WC for my elderly parents. I'm just looking into the regs (WRAS if that's what's required to meet building regs) and realised it's a bit of a minefield! So basically the regs state the wc bidet will be Catagory 5 and require air break water supply. It's not reasonable for me to introduce separate water tanks and heating for one bidet so I'm exploring options. I found this: Nabic 256A Pipe Interrupter / Backflow Preventer - Nabic Valves Online Which on the face of it looks like it satisfies requriments but is there a better cheaper way? Double check valves are not suitable for category 5 so these alone won't satisfy regs. There must be a cost effective way of doing this? Thanks.