I keep water inside the coop year round. I have a metal waterer in there on a heater up on concrete blocks. That keeps it unfrozen and high enough up so that it does not get litter and such kicked into it. In summer, I add a plastic waterer outside in the coop along with the one in the coop. Well, I should say all the time it is not cold enough to freeze the water. But especially in summer, as I find mine would go thru more water in hot weather. Which makes sense. In winter, they often don't stay outside for long, especially when there is snow on the ground, so they need water in the coop. I keep it in a corner and haven't had it knocked over or spilled yet.