Evaporative cooling systems, cooling towers and wet separators; displays and notifications

Operators of evaporative cooling systems, cooling towers and wet separators are obliged, among other things, to apply the state of the art and implement organizational measures during construction and operation.


These installations must be notified to the competent authority. In addition, further notification obligations must be fulfilled.

The 42nd Ordinance on the Implementation of the Federal Immission Control Act (Ordinance on Evaporative Cooling Systems, Cooling Towers and Wet Separators - 42nd BImSchV) obliges operators of such systems, among other things, to apply the state of the art in their construction and operation. Plants within the scope of this ordinance must be designed, constructed and operated in such a way that contamination of the service water by microorganisms, in particular legionella, is avoided in accordance with the state of the art. According to the 42nd BImSchV, these plants must be notified. This can be done nationwide via the KaVKA cadastre website. In Bavaria, a general decree stipulates that the notification must be made exclusively via this portal. In addition, the 42nd BImSchV contains test and measure values for concentrations of legionella in service water.

Legionella are aerobic bacteria that are classified as potentially pathogenic to humans. They are widespread environmental germs that occur in small numbers in surface waters, for example. When water droplets containing Legionella (aerosols) are inhaled, pneumonia can develop, which in some circumstances can even lead to life-threatening infections. Human illnesses occur worldwide again and again either sporadically or in the context of outbreaks. In recent years, Legionella outbreaks with fatalities have also occurred in Germany, for example in Warstein in 2013 and in Ulm in 2010. In addition to contaminated drinking water, evaporative cooling systems, cooling towers and wet separators can also be sources of Legionella. Under certain conditions, evaporative cooling systems, cooling towers and wet separators can release water droplets containing Legionella into the outside air. The goal of legal regulations is to inhibit Legionella growth and reduce the emission of Legionella-containing aerosols from these systems.

Among other things, the ordinance contains the following legally binding notification and reporting obligations for the operator:

  • Obligation to inform the competent authorities if the action values are exceeded (§ 10 Sentence 1).
  • Obligation to notify a new installation (§ 13 Paragraph 1)
  • Obligation to notify an existing installation (§ 13 Paragraph 2)
  • Obligation to notify changes to the installation or decommissioning of the installation (Article 13 (3))
  • Obligation to report a change of operator (§ 13 Paragraph 4)
  • Obligation to be inspected by an expert (§ 14 Paragraph 1 in conjunction with Paragraph 2 Sentence 1)
  • Obligation to notify the authority of the result (§ 14 Paragraph 2 Sentence 2)
  • Submission of an application for exemptions, if required (§ 15).


Whether an installation is covered by these regulations is determined by the scope of application (§ 1) of the 42nd BImSchV.


Notifications according to § 13 of the 42nd BImSchV and notifications according to § 10 of the 42nd BImSchV are to be submitted online via the website of the "Cadastre for the registration of evaporative cooling plants 42nd BImSchV - KaVKA-42.BV".

Notifications according to § 14 of the 42nd BImSchV can also be submitted via this site.

Applications for exemptions according to § 15 of the 42nd BImSchV can be submitted informally to the responsible district administrative authorities.


The obligation to notify according to § 13 of the 42nd BImSchV came into force on 19.07.2018. The operator of a new plant must notify the competent authority no later than one month after the first filling with process water. Existing plants had to be notified to the competent authority by 19.08.2018 at the latest. In addition, § 13 contains further deadlines for the notification of a change or decommissioning of a plant as well as the change of operator.

According to § 10, the operator must inform the competent authorities without delay in accordance with Annex 3, Part 1, and within a period of four weeks in accordance with Annex 3, Part 2, as soon as he has detected an exceedance of action values in a laboratory test.

Pursuant to § 14 Para. 2, the operator shall notify the competent authorities of the results of the inspections pursuant to § 14 Para. 1 within four weeks after completion of the inspection.

Processing time

Information on this can be obtained from the relevant district administrative authority.


Please select a location in "Localization" so that the address of the responsible authority can be filled in.

  • Prefillable Form, Bavaria-wide: Formloser Antrag (mit Unterschrift)
    Please note

    This form has to be signed and sent to the responsible authority. You can sign the form manually and send it by email/fax or sign the form electronically with your qualified electronic signature an send it by (secure) email. If the responsible authority has set up a De-Mail account, you can also send the form by De-Mail using an sender-confirmed message.

    Dieser Assistent unterstützt Sie bei der Erstellung eines formlosen Schreibens, wenn die zuständige Stelle kein Antragsformular zur Verfügung stellt.

Online procedures

  • Kataster zur Erfassung von Verdunstungskühlanlagen (KaVKA-42.BV)

    You can notify evaporative cooling systems, cooling towers and wet separators online in accordance with § 13 of the 42nd Ordinance on the Implementation of the Federal Immission Control Act (Ordinance on Evaporative Cooling Systems, Wet Separators and Cooling Towers - 42nd BImSchV).


  • Display and communications via the KaVKA cadastre are free of charge.

Links to more information

Status: 19.12.2022

Responsible for editing: Bayerisches Staatsministerium für Umwelt und Verbraucherschutz

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  • Online transactions, Bavaria-wide
  • Online transactions, locally limited
  • Prefillable Form, Bavaria-wide
  • Legal bases, Bavaria-wide
  • Legal bases, locally limited
  • Fees, Bavaria-wide
  • Fees, locally limited
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If you select a location under "Localization" the contact details of the responsible authority and, if applicable, locally valid information will be displayed.