Time and again, legionella bacteria in hospitals make the headlines. And especially in a place where there are sick or immunocompromised people for whom pathogens from drinking water can be dangerous. CANZLER presents a quick and practical look at the dangers of drinking water contamination.
The Drinking Water Ordinance (TrinkwV) stipulates that no pathogens or substances in concentrations harmful to health may be present in drinking water. Since 2011, public facilities have been required to regularly test the quality of their drinking water. If contamination is present, the search for evidence begins. The task then is to quickly uncover and eliminate weak points. In such cases, the public health department must always be involved and the remediation case jointly determined.
Hazard analysis reveals deficiencies
First, a hazard analysis is conducted to find the root cause. "In addition to the age of a building, we then look at such issues that are particularly vulnerable," explains Andreas Stehling, one of the managing directors of CANZLER GmbH. "The existing installation is usually given, but usually only as far as known as visible. Intended use, on the other hand, is predominantly related to the user and user behavior." Often the simplest things are overlooked in this context.
- Often, old installed outdoor taps, mainly with long supply lines and not sufficiently protected from frost, are a problem area.
- Another arises with unused areas such as unused staff showers. They provide an ideal breeding ground for germs when the water in the pipes stagnates. Even in occupied patient rooms on wards, this danger looms if patients do not shower during their stay.
- Remodeling or renovation work often leads to the conclusion that "dead lines" are present: In practice, it is seen time and again that installations have been dismantled, but the lines have only been cut or plugged and remain in the walls. This is what causes the germ infestation. Therefore, when preparing a hazard analysis, surveyors or plumbing experts always and especially rely on the users on site, as they are familiar with the history of the buildings.
- Furthermore, the structural condition of the shafts can cause problems: "High-density installation shafts in the ceiling, about 15 to 20 cm wide, pose a hazard per se because of the technology installed in them," says Stehling, division manager for technical equipment at CANZLER. Electricity cables in the vicinity or the hot water heating system carried along, and not infrequently even heating pipes, emit heat to the environment. In many cases, the insulation has deficiencies: it is often too low, destroyed, or adjacent to each other with hot and cold pipes. The heat is transferred to the cold water pipe. It is not uncommon for the cold water to reach over 25 degrees Celsius. Under these circumstances, the clinic management, without knowing it, violated its operator responsibility because of improper use. This is because the required temperature for cold water is below 25 degrees Celsius, and for hot water it is at least 55 degrees Celsius (in the hot water tank and circulation system). It has been proven that bacteria and germs feel particularly comfortable in the spectrum in between and multiply intensively.
- Last but not least, widely ramified networks with few consumers can also be the cause. There, the water stagnates, is therefore changed very little and can also reach temperatures that are no longer acceptable.
Prevention and remedy
Once the cause has been found, the task is to combat it. The first effective short-term measure is thermal disinfection. After a complete inventory of the water-bearing network, technical deficiencies must be addressed first. Depending on the age of the building, it may be necessary to rehabilitate the entire hot water or cold water network. During recommissioning, care should be taken to avoid stagnation in the pipes and thus renewed contamination after the test run. Also, if possible, avoid feeding a new installation from a rather unknown legacy source. "Since prevention is known to be the best medicine, we sensitize the operators where stagnations occur such as in the unused shower for the staff or in the wards," says the expert and publicly appointed and sworn expert in the field of sanitation. As a possible immediate measure, terminal filter systems can be installed. This is cost-intensive, however, filtered water reaches in such a way the use. Such systems must be replaced after a period of use of up to 30 days, with the pure material costs being around 50 euros per filter, not including the personnel costs. Automated flush lines with sensors that can be controlled by the building management system offer one option for monitoring. This helps to document and identify irregularities that indicate a possible defect or even excess consumption.