What is Legionella?

Legionella is a type of bacteria found naturally in freshwater environments, like lakes and streams.  It can become a health concern when it grows and spreads in human-made building water systems.  These water systems may include showerheads, sink faucets, cooling towers, hot tubs, and hot water tanks, and heaters.  This bacteria is the cause of the serious lung infection called Legionnaires disease.