The Parker Ultraviolet Sterilizer processes up to 2.5 gallons per minute, resulting in the 99.8% sterilization of all micro-organisms, such as reproducing bacteria and viruses. Holding tanks (for the product water) are vented, inviting potential contaminants. The bottom line, is there is no control of water quality in the holding tank itself. By using a UV Sterilizer, although optional, the benefits are vast. Please Note: Ultraviolet replacement U.V. lamps are also available. 12 voltage DC .