It would be nice if you could branch out a pipe network vertically and not just horizontally.

It was mentioned in a Devlog 023 - work in progress.

Same comment as OP… It has been a year since this comment. I just started playing and am seeing this as an issue as well. I can bring paint in on 3 floors but if I want to drop one input down into the lower pipes, I cant just drop a T like it can horizontally or as it would in RL.