Drinking Water Ordinance - Legionella Testing and Measurement

Because of the high risk of Legionella infestation, the Drinking Water Ordinance provides for various test measures and also regulates the test procedure. What needs to be checked exactly how and by whom is explained in detail here.

Annual or three-year inspection requirement

The Drinking Water Ordinance lays down certain test obligations to protect people as well as possible against Legionella infections and to help prevent serious illnesses.

In the public sector there is therefore an annual inspection requirement, but also homeowners who rent their apartments are obliged to carry out a review every three years.

Who needs to check when

In the public sector, ie in all public and publicly accessible institutions, companies or organizations must be audited annually. The prerequisite is that water is atomized and made available to the public.

This also affects schools, kindergartens and crèches, as well as, for example, sports institutions or gyms that have public shower rooms where water is fogged. Only through the misting of the water there is a risk of Legionella infection.

For homeowners who own houses with more than two units that they do not use themselves, there is a duty to inspect every three years - whenever

  • there is a water boiler with at least 400 liters of content or
  • between the water heater and the farthest extraction point lines with at least 3 liters consist. In practice this is a distance of about 15 - 20 meters.

This regulation also includes housing cooperatives and property management companies. Only in self-occupied home so no examination is required, but in any case recommended.

Rules for testing

The test must be carried out in such a way that a water sample is taken from at least three different sampling points and examined in a certified, certified laboratory using the usual method (cultivation).

If the test shows a result of more than 100 cfu / 100 ml, a further examination and cause determination is required. If the test shows more than 10,000 CFU / 100 ml (acute contamination) immediate measures are required. Every infestation must be reported to the health department.

Tips & Tricks

Legionella can be present not only in the hot water area but also in cold water pipes and tanks when the water temperature is above 20° C.

Which tests the Drinking Water Ordinance provides for the protection against Legionella, and who must be tested how often, is explained here.

Video Board: Legionella Risk Management