Health risks from legionella – new requirements for evaporative cooling systems operators

20 August 2018 deadline for operators to submit information about existing plants (pursuant to 42. BImSchV)

Klimaanlage auf einem HochhausClick to enlarge
Evaporative cooling systems can be a source of legionella emissions
Source: Fotolia

Evaporative cooling systems, cooling towers and wet separators are potential sources of harmful legionella. The 42nd ordinance implementing the Federal Immission Control Act (42. BImSchV) was adopted in 2017 to prevent legionella outbreaks. The ordinance includes a duty to notify the responsible authorities of these systems. Operators of existing plants must submit information about their plants by 20 August 2018. There is a nationwide uniform process for reporting at In addition, 42. BImSchV includes requirements of plants to report trigger and action values for the concentration of legionella in industrial water.

Evaporative cooling systems, cooling towers and wet separators can – under certain conditions – produce aerosol emissions to ambient air which contain legionella. Breathing in these aerosols can lead to severe pneumonia, sometimes even resulting in death. In recent years there have been repeated outbreaks of legionella in Germany, also leading to cases of death, for example in Warstein in 2013, and in Ulm/Neu-Ulm in 2010.

Consequently, the 42nd ordinance implementing the Federal Immission Control Act (42. BImSchV) entered into force on 19 August 2017. The aim is to prevent such outbreaks. Should they nevertheless occur, the responsible authorities must have the necessary information about the plants which can help to identify which plant may be the source of the outbreak and thus take emergency response measures as quickly as possible. The ordinance makes certain requirements of the operation, production, and installation of systems which can potentially produce aerosol emissions containing legionella. The 42nd ordinance also defines trigger and action values for the legionella count in the industrial water and stipulates requirements for action to be taken if these values are exceeded. It also requires a declaration of existing and new systems, with a 20 August 2018 deadline for existing systems.

Section 13 of 42. BImSchV contains the provisions requiring operators to declare a system and its specifications to the responsible authority. The individual federal states (Länder) are responsible for the enforcement of 42. BImSchV and for ensuring compliance with reporting duties. The registry for evaporative cooling systems (Kataster zur Erfassung von Verdunstungskühlanlagen 42. BImSchV) is accessible online at and provides a uniform format for reporting systems to the responsible authorities nationwide. The portal also provides the contact details of the responsible authorities in all the federal states.

Legionella are bacteria which occur in natural bodies of water and soils and normally do not pose a health risk. But if evaporative cooling systems, cooling towers and wet separators are not operated properly, legionella can grow excessively and be released via exhaust systems. Breathing in contaminated droplets (aerosols) allows the bacteria to enter the lungs, which can result in pneumonia or even death. 

Umweltbundesamt Hauptsitz

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