Dangerous Legionella in Water

The specific type of bacterium Legionella pneumophila, part of the Legionellaceae family, is a particularly dangerous form of legionella. Legionella bacteria live in water; they are Gram-negative, non-spore-forming bacteria. They are pathogenic to humans, meaning they can cause disease.

The danger of legionella in water does not come from drinking contaminated water, but rather from inhaling aerosols generated by misted water in places like showers, hot tubs, faucets, or cooling towers. Inhaling these contaminated droplets can lead to serious illness.

In cold water, legionella are considered harmless because the bacterial concentration is too low to cause harm. Caution is required, however, at temperatures between 25 and 45 degrees Celsius. pH also plays a role: a neutral or slightly acidic environment supports the proliferation of legionella.