Biofilm formation is a problem in cooling towers, as well as, pools, tanks, pipelines, and heat exchangers. It cooling towers, however, there is a bigger problem which is Legionella bacteria.
Legionella bacteria proliferates in biofilm layers and is distributed in the environment through air flow from cooling towers.
This bacteria is pathogenic and causes in lung infection and pneumonia. Most cooling tower operators are suffering from some levels of pneumonia (mild to serious).