Experts urge higher water temperatures after Legionella deaths

Three people have died in a recent increase in Legionella infections in Linz, with large cooling systems suspected as possible sources, ORF reported. Experts say the bacteria can become dangerous when inhaled in fine droplets, such as those produced during showering.

Legionella bacteria thrive particularly well in water temperatures between 25 and 45 degrees Celsius, said Steve-Oliver Müller-Muttonen, chief physician at the Institute for Occupational Medicine in Carinthia. The bacteria occur naturally and can also be found in groundwater.

Under normal circumstances, Legionella do not pose a health risk, Müller-Muttonen said. However, inhaling aerosols containing the bacteria can lead to serious illness. In severe cases, this can cause Legionnaires’ disease, a serious form of pneumonia. Older people, those with weakened immune systems and people with pre-existing lung conditions are particularly at risk.

Müller-Muttonen recommends raising the temperature in household water heaters to between 60 and 70 degrees Celsius. Legionella are damaged at 60 degrees and are rapidly killed at 70 degrees.

Water temperature alone is not enough, he said, because the bacteria can settle in household pipe systems and form films. Regular flushing can help remove them. A three-minute flush is sufficient at 70 degrees, while flushing at 60 degrees should take up to 10 minutes.

This is particularly necessary when water systems have not been used for an extended period, such as after a holiday. Whirlpools and spray humidifiers can also become sources of Legionella, Müller-Muttonen said.