Aoxa...
I've long thought about the winter water issue if I had a large barn like yours with LOTS of birds to water. This is what I "think" I'd do if I had those circumstances and weather like we do.
-I've thought I'd put in a circulating water system using something like a pond pump like they use for the little waterfalls.
-I'd use some kind of trough for the actual drinking containers that is narrow enough that they aren't getting wattles into it...but long enough for the numbers of birds I had in each pen/area.
-I'd use hose or pipe to connect the troughs from "room to room" or "trough to trough" and keep the water pumping in a circle with a drum of water feeding it.
-The drum would have the heater in it...probably an aquarium heater that you can keep good and warm...
-The hose or pipe connected to the drum would exit near the bottom and I'd fill it manually from the top during winter.
Not having done this I'd have to tweak it to make sure that everything was circulating correctly, of course.
But...since I don't have a large barn and lots of birds I haven't worked on one. As always, just pondering.
PS and ETA: Seems like I remember that (Fowlman?) may have been doing something like this but his drinking station was a bucket with the nipples. Whoever it was used an aquarium heater and a pump to keep the water circulating...and whoever it was traveled so they were gone sometime a few days in a row and needed something that would keep the water without a lot of attendance on their part.
In due time.
