1. For chicken water in warmer climates, with frost possible:
2. For chicken water in really, really cold winters:
In the summer time we use a gravity fed nipple-style waterer, and we have been looking for a way to use the nipples in the winter time as well. If you haven't heard of them, check them out. This way there is no chance of poop in the water, because the chickens simply peck at the nipples on the bottom of the bucket, and water comes out.
We found this nice little heated chicken water method on Mother Earth News. This requires electricity. I won't recreate the instructions here, because they do a good job, but I will tell you where we messed up so that you don't have to.
You can throw one of these simple waterers together in about 20 minutes to have nice clean summer water, or in another 10 minutes and get a winter waterer.