Legionella is a type of bacteria commonly found in freshwater environments, such as lakes and rivers. It can also thrive in man-made water systems, including hot tubs, cooling towers, and plumbing systems. When inhaled through aerosolized water droplets, it can cause a severe form of pneumonia known as Legionnaires' disease. In addition to Legionnaires' disease, exposure to Legionella can lead to a milder illness called Pontiac fever. To prevent outbreaks, it is essential to maintain proper water temperatures and regularly clean and disinfect water systems. Awareness and management of Legionella are crucial for public health.