Winter watering - rubber bowls, good or bad?

[littlecoopnextdoor]

I am also in a cold climate. What I do is use this heated dog dish and an outdoor timer so that the bowl is powered for two hours a day, on the off peak hours of our hydro meter. I find that if I run it for the two hours in the morning, it stays above freezing until they're back in the coop later that day (short days in winter). Hope that helps!