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Drinking Water Hygiene & Sampling
to safeguard health


Compliance with the microbiological requirements of the drinking water

The Drinking Water Ordinance regulates the limit values for the concentration of pathogens in drinking water in §5 "Microbiological requirements". It also specifies the testing obligations and periods for large commercial and public systems to check for microbiological parameters such as legionella. Sampling for legionella must be carried out in accordance with DVGW worksheet W 551 and DIN EN ISO 19458.

BEULCO offers a comprehensive range of sampling devices for every application.


Technical background

Human health can be influenced and therefore endangered by many external factors. As the most important foodstuff, drinking water has a particularly high number of contacts with the human organism. Drinking water hygiene is therefore very important in order to protect the quality of the water and therefore also your health.

For this reason, drinking water was placed under special protection as the most important foodstuff in 1998 with the Drinking Water Directive 98/83/EC. For drinking water installations, this means that planning, construction and operation must be carried out in such a way that the installation does not pose a health risk and therefore does not cause illness.

The importance of complying with the regulations should not be underestimated.

Most incidents that lead to contamination of drinking water or contamination with pathogens are the result of non-compliance with technical regulations and inadequate monitoring and hygiene maintenance measures. Microorganisms such as Legionella, Pseudomonas aeruginosa or E. coli are the most frequently occurring pathogens.

Relevant findings show that microorganisms can regrow in drinking water installation systems in buildings despite good water treatment if suitable propagation conditions are created by the operation or planning of the system. Against this background, it is necessary to deal intensively with the most important bacterial pathogens that can occur in drinking water installations, to characterize the risk points and to draw conclusions for planning, operation and maintenance.


Legal background

The German Drinking Water Ordinance stipulates regular, systemic tests for legionella for all large public or commercial systems as defined in DVGW Code of Practice W 551.

The term "systemic" makes it clear that it is not a question of determining the absence of legionella at all individual tapping points, but rather a random sample to determine possible contamination with legionella in parts of the drinking water installation, which can have an influence on a larger number of tapping points - especially in the central parts of the installation such as distributors, drinking water heating systems or circulation pipes.

The amended Drinking Water Ordinance also speaks for itself in this regard. Operators and owners of water supply systems as defined in Section 3 of the Drinking Water Ordinance (i.e. almost all public or commercially used drinking water installations) must observe important new regulations.

Sections 5 and 6 of the Drinking Water Ordinance set out the microbiological and chemical requirements for drinking water and the limit values and parameters to be complied with. However, it is not only the limit values that have been redefined, but also the periods and locations for their examination. Water samples must be taken regularly and submitted for testing.

This affects, for example, apartment buildings, schools, hotels, housing associations, hospitals, care facilities, day nurseries and sports centers. According to worksheet W 551, a large system is a system with a hot water storage tank > 400 liters or a pipe volume > 3 liters. Public systems must be inspected annually, commercially used systems every three years.

In Germany, drinking water is protected by various safety systems on the way from the waterworks to the point of delivery to the domestic installation. The operator of the system is responsible for the quality of the drinking water from the municipal transfer point (water meter) to the actual tapping device (e.g. tap). The operator can be prosecuted if the legal requirements are not met.

Sampling of Drinking Water

Determination of the sampling points

The representative sampling points are selected by means of a site inspection or on the basis of the existing documentation of the drinking water installation in consultation with the responsible health authority. The requirements of DVGW Code of Practice W 551 and the Federal Environment Agency (UBA) must be observed. According to the recommendation of the UBA, "the sampling points must be determined by hygienically competent personnel (e.g. technical inspection bodies, specialist planners or installation companies) with proven qualifications. Proof of qualification is, in particular, a certificate or certificate of training, e.g. in accordance with VDI 6023 or proof of DVGW training specifically on sampling for systemic testing for legionella in drinking water installations".

The Drinking Water Ordinance distinguishes between an indicative and a more extensive test with regard to the scope of the test.

An indicative test is sufficient for an initial assessment of the microbiological status of the drinking water. Samples must be taken at at least three points: At the outlet of the pipe for drinking water (hot) from the drinking water heater as well as at the re-entry into the drinking water heater (circulation pipe) and at the most distant tapping point per riser (e.g. washbasin). Samples do not have to be taken at every riser. It is sufficient if the sampled risers allow conclusions to be drawn about non-sampled risers (e.g. because they are of similar construction or are used in the same way).
For a more extensive investigation, additional samples must be taken from each circulation manifold, from individual floor pipes and from pipe sections with stagnation (e.g. discharge pipes or rarely used tapping points).

Disinfection measures

in drinking water installations

As the disinfection of drinking water pipes is very complex due to the many individual components, it must be carried out by a qualified cleaning service provider for drinking water systems. BEULCO Service is the right partner for this and offers a full service for the removal of contamination in drinking water installations. We disinfect your systems and building installations quickly and reliably, thereby ensuring drinking water hygiene and safety in your buildings. In an acute emergency, we are directly on site.

We use the BEULCO disinfection box for disinfection. Due to its flexibility and mobility, no time-consuming preparation and follow-up work is required. Our service technicians take over the entire process directly on site in consultation with the person responsible for the building.