I am repiping with PEX through out a small house (1 bath, 1 kitchen, fridge, washer/dryer).
I have an idea to running a short copper section immediately from the outside (house main shutoff) to the kitchen sink (where we would use a reverse osmosis water filter system for drinking water). After this I would transition to PEX for everything else.
Would water that touches the PEX ever run backwards into the copper line (regularly)?
Is this a thing? Do people do this?