The week before we were expecting it to be 15 to 20 below zero, I decided to purchase this from Agway. I was having to go out several times a day in 15-32 (above 0) degree weather to chop ice so the chickens could get some water, and I felt they weren't drinking enough. My suspicions were confirmed when the coldest day of the year (20 below zero), I got 9 eggs, and I only have 9 hens. By that time I had the waterer a couple days and I was having to refill it every other day so I knew they were drinking a lot more, and in addition laying more eggs! I am SO GLAD I purchased this!!