As water flows past the UV lamp Ultraviolet light alters the DNA material in cells so that bacteria, viruses, molds, algae and other microorganisms can no longer reproduce. The microorganisms are considered dead, and the risk of disease from them is eliminated. The process of UV Disinfection is accomplished without adding any harmful chemicals to your drinking water and does not distort the water or effect its pH value. UV Disinfection has an effective kill rate of 99.99% of most living microorganisms such as bacteria & viruses.