I couldn't find an answer to this question using Google. I think it's because I am not sure how to ask the question properly. I am not a plumber but I have seen in my new construction house with cpvc and I have seen in the past the same thing done with copper pipe.
When a water line comes out of a wall, just before it comes out there seems to be an area where the pipe goes up a little more and is then capped off. What is the reason for this? Why not just bend 90 degrees out to the source?
Is this necessary with PEX tubing too?