I am planning to build a DIY rainwater collection system using food grade barrels. It is for a tiny house and needs to be easily movable so I thought Speedfit pipes might be a good option. Originally I planned to use the 22mm range but I now see that many of the 15mm parts are cheaper and 15mm valves are more widely available. Would 15mm pipes be okay for connecting the rainwater barrels or would 22mm be better? I will probably connect the system to a small pump. Thanks!