Cooling water in cooling towers for air-conditioning purposes are often subject to microbacterial growth. A disinfection system should always be installed.
Cooling towers and evaporative condensers are used to dissipate unwanted heat to the atmosphere through water evaporation. Water is sprayed into the cooling tower through spray nozzles and tiny airborne droplets are formed.
While falling through the tower, some of the water evaporates but some droplets, known as drift, are carried out of the tower by the air stream produced by the fans. The presence of drift has been detected as far as 6 km away from the cooling tower.
Legionella bacteria grow often in the water and are easily dispersed together with the drift. This water mist can be breathed into the respiratory system, causing risk of Legionella disease and Pontiac fever.
Cases in which hundreds of persons are affected by one cooling tower have been reported