Duties of the owner/building operator
The responsibility of the water supplier ends at the handover point of the building, the water flowmeter. Within buildings, however, germs can rapidly multiply through warming up and biofilm in pipes. Since 2011, regular Legionella tests have been required by German law for large systems with showers and a storage tank of more than 400 litres or a pipeline volume of > 3 litres between the outlet of the water heater and the tapping point.
It is therefore the duty of all owners/operators to design, modernize or retrofit their water piping systems in such a way that Legionella have as little chance as possible. If the limit value for Legionella of 100KBE/100ml specified in the Drinking Water Ordinance is exceeded, it can be assumed that there are defects in the drinking water system or its operation and that measures are necessary.