Drinking water hygiene

Drinking water hygiene

With the "WELL" classification system, the European sanitary valves industry combines its corporate obligations with the explicit recommendation that, in addition to using more efficient valves and fittings to help save water and energy, it is fundamentally more important that the pipe system is constructed in such a way that drinking water quality is maintained right up to the last tap point. The user is therefore advised to employ a professional planer or plumber, who will have the expertise to test whether the following applies to existing systems:

  • hot water provision, and the cold and hot water pipeline system, are insulated and operated in a hygienic and energy efficient manner,
  • avoidable stagnation is excluded, for instance by separating unused sections, so that the necessary quality of drinking water is provided even at the last tap point
  • drainage facilities and waste water pipes are suitable for the changed operating conditions, which are due to new valves.

System operators should also be informed that, in connection with the objective of a responsible use of water and the understandable desire to lower energy consumption, a general lowering of the storage tank temperature for hot water from 60 °C (nominal temperature) to for instance 45 °C can be counterproductive. Such a procedure could result in hygienic problems (growth of Legionella). The basic principle that health protection goes before energy savings should be applied here.

The alternative use of continuous disinfecting processes using chemical agents, for assuring drinking water hygiene even at considerably lower hot water temperatures, is judged very differently by experts. This is caused by disinfectant concentrations, necessary to disinfect systems contaminated with Legionella, that are usually much higher than would be permissible for normal operation according to the German Drinking Water Ordinance (TrinkwV). There is also the risk that the improper use of disinfectants in a domestic installation (dosing errors, system shutdowns, impurities, to name but three) can also pose a threat to human health. And finally, there are so far no extensively supported findings, regarding the long-term interactions between disinfecting agents, biofilms in a domestic installation and the condition of relevant micro-organisms.