I used to use a heated dog bowl, but it would get so dirty SO FAST. It was really gross. And because of the large exposed surface area, it would still freeze when it got really cold.
Now I use this waterer (https://rentacoop.com/products/5-gallon4-horizontal-nipples-chicken-waterer) in combination with a plug-in bird bath heater. This is my year-round waterer, and in the winder I run the bird bath heater plug through the hole in the top of the waterer. I am very luck that when I bought my property, there was an old horse run-in that had electricity/outlets.
I have generally found that keeping the waterer in a place where it can get sunshine but also is protected from the wind can make a huge difference.
And while I know this isn't your question, I do want to mention that even with a heated waterer, you never want to get complacent and assume the water is still good. I check my chickens' water every day (and change it out every 2-3 days), but one day I went out and looked at it and I was like "Great! They have plenty of water!" and then realized just a short while later that the water was frozen. (The power had gone out when I was asleep and the outlet needed to be reset). So in the winter my routine is now to tip the waterer slightly to hear it slosh or tap one of the nipples to make sure that the water is still liquid.
Now I use this waterer (https://rentacoop.com/products/5-gallon4-horizontal-nipples-chicken-waterer) in combination with a plug-in bird bath heater. This is my year-round waterer, and in the winder I run the bird bath heater plug through the hole in the top of the waterer. I am very luck that when I bought my property, there was an old horse run-in that had electricity/outlets.
I have generally found that keeping the waterer in a place where it can get sunshine but also is protected from the wind can make a huge difference.
And while I know this isn't your question, I do want to mention that even with a heated waterer, you never want to get complacent and assume the water is still good. I check my chickens' water every day (and change it out every 2-3 days), but one day I went out and looked at it and I was like "Great! They have plenty of water!" and then realized just a short while later that the water was frozen. (The power had gone out when I was asleep and the outlet needed to be reset). So in the winter my routine is now to tip the waterer slightly to hear it slosh or tap one of the nipples to make sure that the water is still liquid.