What is Legionnaires' Disease?

Legionnaires' Disease is a type of pneumonia. Legionella are bacteria occurring widely in the natural aquatic environment and most commonly in water at temperatures ranging between 20°C and 45°C.

The Legionella organism is found naturally in water sources such as rivers and lakes. In the natural environment Legionella are usually low in numbers and therefore harmless. However, when Legionella get the right conditions of temperature, nutrient supply and pH, they will multiply rapidly, and if there is aerosol formation, like that found in showers and cooling towers, then all the ingredients are in place for an outbreak.