You those inserts that you put into your coffee mug and plug into the cigarette lighter and it keep your morning coffee warm? Well, my grandmother was telling DH and I that they used to make them for chicken waterers to keep them from freezing. She said that the feed stores used to carry them when she used to raise chickens. Has anyone heard of these? Are they still being made? If so, any idea where to get them? Our feed stores have nothing for heating the water. DH is getting tired of his morning ritual of removing the ice and poorly a tea kettle full of boiling water into the waterer to bring the water temp up. We have searched on here for heating ideas, but we are having difficulty finding a good option for their outside water (since most heating elements are rated for indoor use). I would like to note that we live in the high desert of So. California...our night time temps in the winter range from the high teens up to freezing and our day time temps range from the 30s-60s. Most of the time it is freezing at night, but bone dry and windy. While we do get snow here, it is very short lived and not often (couple times a winter on average and usually nothing significant). If we are getting rain, then the temps likely won't be below freezing and we can unplug the heating element and bring it inside, if necessary.