There is provided a water sterilizer. The water sterilizer includes an ultraviolet light source electrically connected to an electrical power source, a light-protective housing encasing the lamp and having an inlet and an outlet, and a pump to draw the water into the housing to expose the water to ultraviolet light. Electric power supplied to the ultraviolet light source has an operating potential of not greater than 24 Volts. There is also provided a method for water sterilization.