Wonder no more. I use empty Oxyclean (actually it's a knock off brand - but who is checking; you know what I mean) buckets because I get them for free and I can have lots of them making it easy for me to switch out frozen/mucked up water in no time. (Just bring in frozen one and take out a fresh one.) They also have nice handles on them and are the correct height for standard size hens to drink from. I don't recommend them for inside the coop, but, since I only water in the runs, they work for me.
I use a gallon waterer purchased at Tractor Supply for the summer time watering. In the winter when it freezes in a matter of hours, I use a square ice cream pale, the kind wal mart has... but not the cardboard ones. Anyways, like emys was saying- keep a few to easily change out water.
I have a 5 gal bucket with pvc pipe nipple waterer running into the coop/run. Since it freezes up in winter, I'm using a heated dog water bowl. Both systems have been fabulous.
