Evaporation cooling towers offer an ideal setting for the growth of microorganisms of all sorts. Particularly when water is used in industrial applications, high inputs of nutrients and raised temperatures cause especially heavy contamination. In unfavourable conditions, the growth of Legionella can reach concentrations hazardous to health, and infect bystanders as a mist (aerosol).

Disinfection options are limited by legislation, which in many countries stipulates limits for combined chlorine and biocides. Treating cooling water with UVC is a very good alternative to using environmentally hazardous and poisonous biocides or chlorine.