Legionella is a type of bacteria that grows in water. There are several species of the bacteria that can be hazardous to health when they get into the lungs. Legionella is commonly found in natural water sources, such as rivers, lakes and reservoirs, but usually in low numbers. It may also be found in purpose-built water systems, such as cooling towers, evaporative condensers, hot and cold-water systems and spa pools. When conditions are favourable, the bacteria will grow and multiply.
