Abstract: A thermally controlled drinking water system for animals having a thermally insulated cabinet containing a water reservoir, a water bowl, a vapor-compression refrigeration water-cooling system, and an electric water heating system, maintains the drinking water at an optimal temperature in both hot weather and freezing weather conditions. The reservoir stores at least five days of water and automatically maintains the water bowl in a constantly filled condition through a water supply conduit and visual indicator indicates when the reservoir water level is getting low. The evaporator coil of the cooling system is engaged with the water bowl in heat exchange relation and electrical heating elements are engaged in heat exchange relation with the water bowl and reservoir. Cooling and heating operations are controlled by an ambient air temperature sensor on the cabinet exterior and a water temperature sensor on the side wall of the water bowl.