If you haven't yet, do it! For five years, Farmboy and I have been hauling water from the house to the barn. During winter, the trek is made several times a day to keep the water thawed. This year, December 2016, I invested in some heated buckets. I purchased mine from Tractor Supply but they are available a lot of places.
I wanted to know more about how they work so I called the company, Miller Manufacturing Company, and asked a couple of questions. The thermostatic control turns the heater on if the water gets below 42 degrees F and turns off when the water reaches 60 degrees F. They will keep water ice-free down to -20 degrees F. They use .9583 amps.
I wound up needing an extension cord for mine. The buckets are LOCKNDRY compatible (a type of extension cord) if your extension cord will be used outside. Since my buckets are inside the sheep barn, I bought a 16/3 wire outdoor extension cord (the same gauge wire as the LOCKNDRY cords). Be sure and purchase the shortest extension cord you need for safety. Now is a good time to purchase cords because of the holiday season and folks needing them for outside lighting and decorations. It seemed like there was more options for shorter cords than what there normally is. I only needed an 8 and 10 foot cord.
I also sat the buckets inside of a rubber feed tub so the straw I use for bedding won't wind up right next to the buckets. This makes me feel a bit better about the safety aspect of the buckets. I also use a double-sided hook to attach the handle to a fence so they don't get tipped over. During the summer, once the cord was tucked into the bottom compartment, I sat them on a couple of 4" x 8" x 16" concrete blocks layed side-by-side.
I don't know how I lived without these!
Note: Folks have commented one must make sure the buckets do not get totally empty. They will still keep heating and the possibility of a fire is there.
Below is an example of the rubber feed bucket, I had also purchased them at Tractor Supply and had a few on hand.