I use a 14 gallon clear plastic tote with lid, horizontal nipples, and a 250 watt stock tank deicer that is rated for use in plastic. The deicer has a thermostat. It keeps the water thawed, not warm. Turns on about 35 degrees and turns off when the water reaches 40 degrees. I get the clear tote so I can easily tell when the water is getting low. This has kept the water thawed even when we've had temperatures down to -26 F. This keeps my chickens in water for about 2 weeks which makes things so much easier in frigid winter. I also have a heated dog bowl in the shed just in case the deicer dies.