If "in al" in your username means "in Alabama", I should not think you'd have to heat at all, certainly not right now. (Next year they will have larger combs). It is FINE for the water to freeze, that is NOT a problem at all, just replace it with fresh liquid water in the morning. Really. Chickens are only 60% water, they do not turn into icecubes at 32 F
Good luck, have fun,
Pat

Good luck, have fun,
Pat