Hygiene Problems
Hygiene Problems

Over the last few years, it has become obvious that serious microbiological problems can be lurking in drinking water installations. New research shows that bacteria in drinking water are responsible for far more infections than was previously thought.

Trade professionals believe the weak points are primarily:
Incorrect and unprofessional installation of the piping system
A lack of hygiene during installation or commissioning
Operating errors after commissioning


The following measures are especially important during the planning and installation of drinking water systems:

Do not create a breeding ground for bacteria by selecting suitable materials
Reduce stagnation times by choosing pipe dimensions compliant with use and taking into account actual pressure losses and the user’s behaviour
Insulate properly to prevent an impact on the drinking water quality caused by heating or cooling


To breed in drinking water, microorganisms require certain temperatures. For this reason, the temperature of the cold water should not exceed 25°C and the temperature of the hot water should not fall below 55°C. The presence of the following bacteria, among others, in drinking water systems is an indicator of water quality:


Pseudomonas Aeruginosa


This bacterium is one of the most important pathogens passed on by drinking water – especially through infections contracted in hospitals. Its optimal breeding temperature range is between 25 – 30°C. No pathogen should be present in a water sample of 100 ml, as, according to the Robert Koch Institute (RKI), even the lowest of concentrations is considered harmful to health. Treatment of the triggered infections is difficult. In humans, they can lead to severe inflammatory organ diseases, even resulting in death. The presence of pathogens in drinking water installations causes buildings to be immediately closed and subsequent renovation work to be carried out.


Legionella Pneumophila


Legionella breed most effectively between 25 – 45°C. In 1976, the first known Legionella epidemic caused 30 deaths in a hotel in the USA. Since then, the press has often on reported similar cases. In Germany, there are approx. 30,000 cases of Legionella illnesses each year. With a fatality rate of 10 to 15 %, this means approximately 3,000 deaths per year. The infection rate is much lower in other countries: 34.1 (Spain), 19.2 (Denmark), 17.9 (The Netherlands) and 16.9 (France) per million inhabitants.


National and EU Regulations


To avoid problems, every country has regulations for the safe supply of water. New regulations, which compliment or replace national regulations, are constantly being introduced by the EU. EN 806 and EN 1717 are important European standards for the preservation of drinking water quality. This makes it necessary to consult the regulations for such technology on a regular basis and to use them in practice at short notice. For example, in Germany the dry leakage test has become standard in large installations such as hospitals or hotels due to reasons of hygiene. Even the flushing of the installation takes place as late as possible. In some countries, inadequate drinking water quality is a criminal offence.


The highest possible drinking water quality is only possible as a result of cooperative responsible action from planners, installers and operators.


Read on:
Planning of drinking water installations

Pseudomonas aeruginosa is one of the most significant pathogens of infection that can be spread through drinking water in buildings.