Drinking water hygiene with GeberitProtecting lives

An underestimated source of danger

Showers are a possible source of legionella infection

Legionella bacteria live in water and can cause legionnaires' disease. According to studies conducted in Germany, the number of deaths for which they are responsible equates to those caused by road accidents.

Infection happens through the inhalation of droplets in the shower, for example. Pseudomonas and other germs also create sources of danger.

Hot or cold and always on the move

It is true that drinking water is never completely germ-free, but normally the concentration of germs is harmless. Health risks only arise when the germs are able to multiply. Stagnant water and water temperatures between 25 °C and 50 °C can encourage bacterial growth. In practice, the risk is likely to occur in empty properties, in rooms that are only used intermittently or in cases where dead-end pipes are not in use.

Hygiene problems caused by excessive proliferation of germs can be reliably avoided through:

  • correct planning, design and commissioning
  • correct operation
  • avoidance of stagnation
  • avoidance of unfavourable temperatures between 25 °C and 50 °C

Our drinking water is not sterile; it contains microorganisms that form biofilms. These do not normally pose any problems or affect the quality of the drinking water. A stable ecosystem even seems to have a positive effect on water quality. Nevertheless, biofilms can also form a breeding ground for germs that are hazardous to health.

Accurate measurement of legionella growth

The graphic shows how the legionella count doubles per day. The measurements were carried out in a nutrient-rich environment compared to normal drinking water. (© Geberit)

Working on behalf of Geberit, Dr. Hubert Hilbi and his researcg group at the University of Zurich have been systematically investigating legionella growth.

The proliferation of legionella increases with increasing temperature up to a maximum point. At 40°C, legionella double around three times more frequently per time unit than at 25°C. Instead of doubling twice from 1 to 4 at 25°C, the legionella double six times from 1 to 64 at 40°C.

VDI 6023-1 requires a complete water replacement every 72 hours and cold water temperatures not exceeding 25°C after 3 litres have been drained (orange line in the graphic). In practice, however, it is not always possible to avoid temperatures in the critical range.

The temperature-dependent flush interval

Temperature-dependent flush interval curve (© Geberit)

A temperature-dependent flush interval (blue dashed curve) can be calculated based on the measured multiplication rates. In accordance with VDI 6023-1, it is assumed that a flush interval of 72 hours is sufficient at 25°C. For higher temperatures, the flush interval is calculated in such a way that the legionella can multiply equally frequently during this time. This results, for example, in a flush interval of 46 h at 29°C. In this way, an increased risk of contamination can be avoided even if the cold water temperatures cannot. Also, according to a research report by the DVGW, short-term temperature increases to over 25°C do not immediately lead to high legionella findings

All aspects at a glance

Problems and solutions in the installation of drinking water pipes
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For fresh drinking water that is always well received

Geberit hygiene system – For fresh drinking water that is always well received (© Geberit)

When it comes to creating an efficient concept for hygiene management in buildings, Geberit offers a comprehensive solution that really does tick all the boxes.

The aim: To offer customised solutions to maintain the drinking water quality in every sanitary installation and for every type and frequency of use.

The solution for new and existing buildings

Geberit products for drinking water hygiene

Geberit Mapress

Protective caps

  • Geberit pipes and fittings are protected with caps
  • The protective caps prevent contamination during storage and transport
  • Do not remove the protective caps until immediately before installation
  • Replace the protective caps during interruptions in installation

Standards and laws

Guaranteeing drinking water quality in domestic installations is the subject of various ordinances and standards. At a European level, Directive 98/83/EC governs the quality of water for human consumption. Sanitary engineers, plumbers and operators are safe from a legal perspective if they observe directives like this and comply with country-specific regulations.

Directive 98/83/EC


Optimal drinking water hygiene

Find out about our contribution to optimal drinking water hygiene.

All the technical information for Drinking watercan be found in the product catalogue