The existing recommendations for sustainable drinking water hygiene are inadequate. In addition, the practice of sampling is questionable: place and time of the sampling are communicated early to the affected companies, allowing a manipulation of the measurements. By rinsing with hot water, the number of bacteria present can be reduced to normal values or they are put into a viable but nonculturable state (VBNC), so that they cannot be detected. In fact, Legionella are only eliminated after a 30-minute rinse at 75 °C.
In contrast to hot water, there is no obligation to check drinking water regulations for cold water.The operation of drinking water systems according to the usual recommendations is legal, but does not guarantee complete protection against contamination. More information can be found at: http://www.legionellenschutz.com