We are in the process of making something like that. We will be using threaded nipples, so the chickens drink from below by pecking at the steel post valve. We've decided to tap threads in the pipe so that we can use teflon tape instead of silicon seal. We used silicon when we put nipples in the bottom of a bucket. If the silicon is on the outside the girls peck at it & eat it (yech!). If it's on the inside it collects an unappealing biofilm (also yech).
We got 1" diameter schedule 40 pvc pipe, so it is thick enough to take the threads and big enough to take the nipples. The chickens are already cool with the nipples in the bucket. This way we can hook the whole thing to a garden hose for now & a permanent line later, and know they aren't running out of water.
When we get it all sorted out & working I'll post more details.