There was a post (of course I can't find it) I think in coop construction where a guy made a waterer out of 3" PVC. It was basically a "J" with a cap glued on the top and two 90-degree elbows making the curved part. He said he just laid it on its side to fill it, and then when you set it upright it functions just like a normal vacuum waterer. I don't remember how he had it mounted, but the advantages are 1) adjustable height, 2) small opening so not as much dust/junk gets in the water, 3) it's harder for them to stand on top of it and poop in it, 4) it doesn't look like a big old waterer, 5) it could be mounted on the outside for easier removal/refilling, and 6) you can paint it whatever color you want.
As you can see, I was quite taken with the design and I really want to make one!