I've been looking for a solution as well and sadly there isn't one that is convenient, safe and cheap at the same time.
In my opinion, the best solution if you have a small flock is to change the water several times a day. It's a pain, but the alternatives have many drawbacks. Here's some things to consider.....
Electricity:
- The safest and easiest approach to get power to your hens is to pay a professional electrician to bury the cord underground in approved pipe. This is expensive, but you can be confident that the power supply will be safe.
- Extension cords - If you go this route, you need to buy an extension cord that is designed for outdoor use and make sure it is designed to handle the electric load for your heating element. Heaters draw lots of power, so this is important. The guage of cord depends on the draw of the heating element, so determine this first and then get the right cord. That said, I don't like the idea of using extension cords over prolonged periods of time -- People can trip over them, pets and other animals can gnaw into them, rain or snow might get into the plug over time and cause a short. etc.
-Solar Panel and battery - This will cost a few thousand dollars. This seems like a lot of money if all you have is a backyard flock, not a commercial operation.
-Bowls painted black or devices like the "solar sipper" - the sun will warm the water a few degrees but not prevent the water from freezing for those who really experience this as an ongoing problem. Reviews from people who own the solar sipper suggest that it is of limited value. Needless to say, if you have overcast winters, this won't work at all.
Heating Elements:
- Bird bath de-icers and bucket heaters etc. These do work, but there's a danger in using them; If the insulation on the wiring gets damaged, the water will become electrified. Every year, livestock is killed by these devices. From an economic perspective, this is more of an issue with thoroughbred horses and cattle than chickens, but no one wants to go into the yard and find a flock of dead chickens. Be careful when using these devices and check to make sure that their is no fraying of the wires. You will also need a thermostat to turn most of these devices on and off.
Other Solutions:
- Salt - I've seen some people suggest adding salt to water to prevent it from freezing. Salt does change the freezing point of water but you need to make the water quite salty to achieve this. At that level of salinity, the water is undrinkable as it would throw off your chicken's electrolyte balance and kill them.
-Vinegar - I've also seen some people suggest adding vinegar to water to prevent it from freezing. While there is evidence that increasing the acidity of water is healthful for chickens, adding vinegar to water will not prevent it from freezing. I actually ran an experiment and placed water and water with vinegar into glasses and put them into my freezer. The water with vinegar froze just as fast as the pure water.
