Legionnaires' disease is a serious disease caused by Legionella bacteria, which thrive in stagnant, warm water. Outbreaks of this disease have been associated with cooling towers, evaporative condensers, showers, faucets, hot tubs/whirlpool spas, and other sources of aerosolized water. Legionella bacteria favor a temperature of 25-42 C (77-108 F) for growth. Because many buildings and cooling towers may be shut down during or after a disaster, the water in those systems may sit stagnant for days to weeks--providing an increased risk of Legionnaires' disease once the systems are restarted.

Stephen B. Thacker CDC Library collection