Hi, I've installed a water softener and my pipes are 15mm and the supplied softener inlet and outlet plastic pipes are 22mm - with plastic 3/4 hand tightening connectors - these are connected to a supplied bypass device so no need for any adaption. When I connected the softener pipes to the bypass device and turned my water on the connectors leaked regardless of how tight they were. I saw they were rated as 10 bar so I bought some 15mm washing machine pipes also rated as 10 bar from Screwfix. They fit fine and no leaks. I've then read the instruction manual and it says washing machine pipes are not to be used under any circumstances. I just wanted to check if what I've done is safe please - I had assumed if the pressure rating was the same it would be fine. Thanks