The legionella bacterium can be found in cold and warm water pipes and prefers to reproduce in high temperatures (25°C to 50°C). Through the inhalation of fine water particles, this bacteria can get into the lungs and cause legionnaire’s disease.
Even if your drinking water has tested positive for legionella, there is no immediate need to panic. The bacteria begins dying off at a temperature of 60°C. The first step in eliminating legionella is thermic disinfection. In this process the water gets heated up to over 70°C in order to properly rinse out the pipework. If legionella is still detectable after this process, a chemical or chlorine rinsing (chemical disinfection) is necessary. Another option is a procedure called anolyte and evirolyte.
The biggest mistake one can make is to completely turn off the water, which will cause the bacteria to likely spread even further in standing water. This is why seasonally used constructions such as camping grounds, garden houses, secondary residences, kindergartens and schools or universities are at a higher risk of infection.