Legionella is usually found in freshwater settings, including lakes, rivers, and streams. It can also survive in soil. But most people don’t get Legionnaires’ there.

Legionella thrives in warm water. It often spreads through a building’s contaminated water system.

It’s actually an airborne disease. The bacterium is so tiny that it can hitch a ride inside tiny water droplets such as mist and water vapor. You can then breathe in those droplets, such as in the steam from a sauna or hot tub, and from there, the bacteria make their way into your lungs.

Rarely, you can get legionella by drinking contaminated water that goes down the “wrong pipe”: your trachea (which goes to your lungs) instead of your esophagus (which goes from your mouth to your stomach).

How does Legionnaires’ disease spread?

Legionella bacteria can grow and spread in water systems including:

Is it contagious?

No. Legionnaires’ doesn’t spread from person to person.