HOW DOES ULTRAVIOLET RADIATION WORK?
Ultraviolet radiation sterilizes water. Sterilization implies that life such as bacteria, viruses, yeasts, molds, and algae are destroyed. For UV radiation to work, a 2537 Angstrom unit (254 nanometers) wavelength must come in contact with the microorganism to inactivate it. When ultraviolet rays reach the microorganism, they strike the heart of the organism destroying the DNA (deoxyribonucleic acid) and preventing it from reproducing. Table I give the amount of UV necessary to kill various microorganisms. The Public Health Service does not require water to be completely sterilized to be potable, but water must conform to the departments drinking water standards or those of the agency governing your supply. To meet drinking water standards, the supply must contain less than 2.2 coliforms per 100 ml. The microorganisms in the coliform group are usually associated with fecal matter or human and animal wastes and suggest the presence of pathogenic (disease-causing) organisms such as typho
