Hot water has been around since man first harnessed the power of fire, but when at elevated temperatures, it is dangerous and even deadly. Today’s hot water heaters offer a diverse range of technologies that perform leaps and bounds ahead of their predecessors, but what temperature should they deliver? Some facilities may simply set the heater to a usable temperature, but while this may seem like an acceptable practice, there is an issue that needs to be addressed: Legionella.
One of the biggest concerns for hot water systems in commercial buildings is Legionella bacteria. Legionella is a bacterium that enters the human body by inhalation and aspiration of water droplets, and is responsible for Legionnaires’ disease, a bacterial infection of the lower respiratory system that often gets misdiagnosed as pneumonia; one in 10 people who contract Legionnaires’ disease will not survive. Below is a Legionella Growth Chart, which shows the bacteria growth behavior. These organisms live and multiply in water between 68° F and 122° F, and thrive in water 95° to 115°. At 121°, Legionella bacterium stops multiplying, but is still present in water.