A stand-alone ice making appliance and method of operation is provided. The stand-alone ice making appliance may include a container defining a first storage volume for receipt of ice, a water storage volume in fluid communication with the container to receive water from the container, an ice maker, a pump, and an ultraviolet light source. The ice maker may include an auger at least partially surrounded by a casing. The casing may be in fluid communication with the water storage volume to receive water from the water storage volume. The ice maker may further include a sealed refrigeration system in thermal communication with the casing. The pump may be in fluid communication with water storage volume for actively flowing water from the water storage volume to the ice maker. The ultraviolet light source may face the water storage volume to selectively direct ultraviolet light into the water storage volume.