Hygienic-technical inspections and assessments of drinking water installations

If there are problems with the drinking water quality in drinking water installations, for example in the case of contamination with microorganisms, the building operator comes into conflict with § 5 of the current Drinking Water Ordinance. This stipulates that the generally recognised rules of technology and the specified limit and action values must be complied with. The water must be pure and fit for human consumption so that there are no adverse health effects for the users. If defects or deviations are detected, the operator is responsible.

To prevent problems, the guideline VDI 6023 "Hygiene in drinking water installations" can be consulted. Health risks, especially in large complex drinking water installations, should be assessed objectively. If hygienic problems have already occurred, a risk assessment is of considerable importance. Only by analysing the complex interplay between water chemistry, physical and hydraulic parameters as well as the microbiological situation in the domestic installation is a permanent solution to the problem possible.

Our services range from the hygienic-technical inspection and analysis of the drinking water installation, the microbiological and chemical examinations, the development of remediation proposals to the monitoring and control of the remediation.


Christian Büning

Am TÜV 1
45307 Essen

Tel +49 201 172 1367
Fax +49 201 172-1606


VDI 6023 - Hygiene in drinking water installations

The guideline VDI 6023 takes a holistic approach to the topic of drinking water hygiene, describes the issues and defines requirements. These not only directly affect the topics of production, planning, construction, maintenance and operation, but also regulate the interfaces between them.

This is accompanied not only by testing obligations for legionella, but also by testing obligations for drinking water installations and the legal obligation to assess the risk if the technical measure value for legionella (100 colony-forming units (CFU)/100 ml) is reached or exceeded in these tests.

What are the risks of hygienic deficiencies in drinking water installations?

The health risks associated with the use of drinking water can result from chemical as well as microbiological stress. In the case of chemical loads, an acute hazard to drinking water users is very unlikely. The primary focus here is on the long-term prevention of possible chronic health impairments, For example by lead.

In contrast, risks caused by pathogens in drinking water can lead to acute hazards in the form of infections. According to current knowledge, it is mainly bacteria from the group of legionella from which a significant risk potential in drinking hot water installations emerges. These microorganisms can lead to so-called legionellosis. As an easy progression, the Pontiac fever, this infection shows summer flu-like symptoms. Estimates are based on an annual fall in the six-digit range. In the case of the severe progression of legionellosis in the form of lung inflammation, the legionnaires' disease, the Robert Koch Institute, Berlin, also assumes a considerable underwriting of the cases and a dark figure of> 95%.

After evaluating the findings to date, it is assumed that approximately 800,000 outpatient pneumonia acquired annually is about 4% due to legionella (see also the Justification of the Drinking Water Act). This is about 32,000 illnesses a year with the consequence of about 2000 deaths. This shows the current darkness and the extent of the problem.

In which areas is the guideline VDI 6023 valid?

The VDI 6023 applies to all drinking water installations on properties, in buildings and on merchant ships (including inland waterway vessels). This also includes "drinking water installations from which drinking water.... is supplied to consumers (building water supply installations).", which fall under § 2 of the Drinking Water Ordinance.

Is there a legal obligation to implement the VDI 6023?

The VDI 6023 is one of the most important generally accepted rules of technology for drinking water installations. The Drinking Water Ordinance requires that the generally accepted rules of technology must be complied with in §4 and also in various places. This concerns the aspects of manufacturing, planning, construction, commissioning, use, operation and maintenance.

What are the objectives of VDI / DVGW 6023?

The Directive defines requirements for the hygiene of drinking water installations. This is the totality of all efforts and measures for the prevention of indirect or immediate health impairments and disturbances of the well-being of the individual user.

The aim is to preserve the perfect drinking water structure in the drinking water installation and to comply with the limit values of the drinking water ordinance.

What are the requirements of VDI 6023?

For example, The VDI 6023 defines hygienically justified structural, technical and organizational requirements with regard to the planning, manufacture, execution, operation and maintenance of drinking water installations. The planning may only be carried out by experts.

As a planning basis a room book with the usage description and a complete concept of the drinking water installation must be available. With reference to other regulations, such as EN 806,  DIN 1988 and EN 1717, requirements for the construction, the material to be used, as well as necessary maintenance measures, including the controls, are described.

Also, interruption operations, e.g. Are subject to the requirements.

The VDI 6023 systematically describes these requirements and also deals in detail with the interfaces between the partial tasks. The details are, among other things, the subject of the u. Drinking water hygiene training.

Is there a test obligation for drinking water installations according to VDI 6023?

The obligation to test is derived from the Drinking Water Ordinance and the associated requirement for adherence to the generally accepted rules of technology. Within the framework of the commissioning of the drinking water installation, an initial hygiene inspection is to be carried out in accordance with VDI 6023.

At the same time, compliance with the requirements for planning and installation must be thoroughly tested before filling the drinking water installation. This test may only be carried out by qualified persons with additional hygienic qualification.

A further test obligation, which relates to legionella in drinking water installations, is derived directly from the drinking water regulation. In the case of large-scale plants (> 400 liters of storage or> 3 liters of water from the storage tank to the final tap), the water is atomized (eg showers) every year or every three years the water is examined for legionella.

What requirements does the VDI 6023 require for the qualification of the personnel for drinking water installations?

The VDI 6023 requires an additional qualification in the form of hygiene training from everyone who works on drinking water installations, in addition to the basic professional qualification. A distinction is made between a drinking water hygiene training course, type B (1 day), drinking water hygiene training for type A (2 days) and a briefing (for operators). The hygienic training type B is for all persons who erect and maintain drinking water installations. Persons performing planning tasks, carrying out responsible tasks or carrying out auditing activities require hygienic training according to type A.

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