http://m.ebay.com/itm?itemId=301330970374 This is a cure all for frozen water. Not only does it keep water from freezing BUT cement is soooo of at holding heat that it actualy disperses in the air and will make your coop warmer! Without any bright lights or dangerous direct heat sorces. This is awrsome. If I take the water off the block my chickens will play king of the mountain to sit ontop of it hahaha usualy they all cuddle around it. It's defenitly a life saver. Especially I you have a galvanized steel waterer. No bpa and the steel will hold heat better than plastic.