This Small Innovation Research (SBIR) project will bring to market a low power, point of use (PoU) water disinfection system designed to retrofit into existing passive (non-germicidal) filtration systems. This project will use ultraviolet light emitting diodes (UV LEDs) along with a novel and proprietary flow cell design, resulting in PoU water disinfection. Current ultraviolet PoU water disinfection is accomplished using discharge lamps, which requires high voltage, ballasts, and a relatively large form factor. The use of UV LEDs instead of discharge lamps will allow the light sources to reside inside a smaller form factor, and to function at lower overall electrical power, without line voltage and ballasts. Furthermore, the proprietary optical design of the flow cell will improve upon conventional flow cells by maximizing the ultraviolet dose received by microorganisms in the water, and increasing their residence time in the flow cell. <br/><br/>Currently, there are no PoU systems employing UV LEDs as the germicidal source. If successful, the product developed under the phase II program will be the first of its kind and provide a point of entry for UV LEDs into the large PoU water sterilization market. The low power aspect and small form factor of the flow cell will make the system potentially suitable for battery operated field applications where line voltage is not available. Such applications may include military or medical field operations. Overall societal impact should be significant, particularly in markets outside the United States where there is increasing concern about water sterility.