The new German drinking water ordinance (Trinkwasserverordnung, TrinkwV), came into effect on 1st November 2011. In this update, not only public buildings, but also commercially used buildings such as apartment buildings are to be tested for Legionella spp.. An “action level” of 100 cfu/100 mL has been introduced as the maximum tolerable concentration of Legionella spp. in drinking water (Schaefer et al., Bundesgewsundheitsbl 54: 671-679, 2011). In reaching or exceeding this value, the health authorities can compel the building operator/owner to identify and eliminate the cause of contamination. Implementation of water hygiene and engineering solutions to reach the target of less than 100 cfu/100 mL for Legionella spp. are necessary (Gollnisch & Gollnisch, Bundesgesundheitsbl 54: 709-716, 2011; Hentschel & Heudorf, Bundesgesundheitsbl 54: 717-723, 2011).
A further study (Arvand et al., Eurosurveillance 16(16), 2011) highlights Legionella spp. contamination in the cold water supply. According to the German drinking water guidelines, cold water is not routinely tested unless its temperature exceeds 25 °C. In this study no clear correlation between the cold water temperature and the contamination level was evident, although 35% of cold water samples below 20 °C at collection were contaminated. The importance of risk assessing the cold water supply in healthcare facilities for Legionella spp. is therefore highlighted.