Hi! A simple question here, which you guys will know the answer to straight off and only an amateur like me would ask!! I'm looking to use flexible pipes to take the supplies to my washing machine, (as there will be no service void behind the cabinets), but the catalogues say I need to use a check valve with them. I've googgled check valves and looked through this site, so know what a check valve does, but why do I need one if I use flexible pipes instead of copper pipe? (Feeling nervous now as I've used flexible pipes before, but not fitted check valves! ) Any other advice will be very much appreciated. Thanks in anticipation.