Limits for drinking water: 100 CFU/100ml, for healthcare facilities 0 CFU/100ml
- Does not smell
- Does not change the taste of contaminated water
- Becoming ill with potentially fatal Legionnaires disease
- Becoming ill with a lighter version of legionellosis – Pontic fever
Removal of legionella bacteria
- Water disinfection with chlorine dioxide
Legionella is a common bacteria. It can occur practically in all waters in harmless quantities. At temperatures of 32-42 °C it begins to multiplicate intensively.
Legionella is not harmful if you drink it (and since hot water is not intended for drinking, it should not normally be a threat), but when it enters your lungs, it causes legionellosis. The inhalation of legionella occurs most often when showering. Especially people with reduced immunity, old or sick people, are at risk. Therefore, the limit in healthcare facilities is tightened. Legionellosis manifests itself as a common respiratory disorder. It is therefore poorly identifiable, and if the right treatment is not applied, the death of the infected can also occur (annually there are over 400 confirmed fatal cases in the European Union).
There are several ways of defending from legionella. Smaller domestic boilers automatically overheat once in a while to a temperature that kills legionella. With larger distribution systems, such a solution is uneconomical, dangerous and often ineffective (it is not possible to achieve sufficient temperature throughout the whole system). Therefore, chemical disinfection is used. The most effective of the available substances is chlorine dioxide. It, unlike the others, can destroy the biofilms in which legionella is hiding and multiplying.
