People usually contract Legionnaires’ disease by breathing in Legionella bacteria in very fine droplets of water called aerosols. Artificial water systems, including showers, spa pools, fountains, car washes and cooling towers, may provide environments that allow Legionella bacteria to multiply in large numbers. Legionella can then be spread by aerosols.

The risk of Legionnaires’ disease can be reduced by ensuring the growth of Legionella bacteria is controlled in systems such as spas, hot water systems and cooling towers. 

Cooling tower systems and water delivery systems are regulated by the Public Health and Wellbeing Act 2008, and the Public Health and Wellbeing Regulations 2019.