Not just to keep the water from freezing but to store and pump water to the pigs. The large black cylinder is a storage tank. The storage tank is connected to a water bowl with a float valve. I’m using a pressure pump from an RV to mo water from the tank to the bowl.

This way, I don’t need to haul fresh water every day. Whenever the pigs take a drink, the bowl fills itself from the reservoir. I only have to fill the reservoir every week or two depending on how hot it is outside. It saves me a lot of time and energy.