I have read tons of articles on keeping water heated inside of a coop in the winter, and this is the route that I am interested in going. I do not want to constantly change frozen water. I do not want to use a dog bowl to heat the water, or use a light bulb to heat the water. This is the route that I would like to go. I would also like to partially insulate the water container. I have read a lot of information about types of insulation, and I am trying to figure out some way to line a 5/10 gallon bucket with mylar, inside or outside. If I do it outside, I would like ideas on how to cover the reflecting properties of the Mylar. I am concerned that paint will just flake off of it. I am also concerned that the mylar will insulate too well, and that I will have very hot water in the winter time, and waste electricity. Please do not warn me about the dangers about adding electricity to the coop. I am working with an electrician to minimize/ eliminate that risk. I am only interested in hearing about methods of heating sealed water buckets with nipple waterers. Please let me know about submersible water heaters that you are familiar with, that do not heat the water to levels fish swim in, but levels that prevent water from freezing. Thank you for your wisdom and time.