Legionella in tap water: prevention, control and control - FFT Ecology News

Legionella in tap water: prevention, control and control

Tap water in Germany is considered harmless. As long as certain requirements are met. Otherwise, it can become a major health hazard. What should you watch out for?

How does a Legionella infection take place?
How can the risk of infection be minimized?
When the risk of infection is particularly high
Statutory Regulations
Symptoms of Legionella infection

Consumer advocates and authorities repeatedly warn of a health risk from too high a Legionella concentration in the in-house drinking water system. The pathogens transmit the dangerous legionnaires’ disease (legionellosis), which can even be fatal. The risk of infection is particularly high when showering. How can you avoid a dangerously high concentration of Legionella in the Drinking water prevent?

How does a Legionella infection take place?
Legionella are mobile rod-shaped bacteria that can be found in almost all types of water – including in the Groundwater – can occur. “Therefore, legionella can also be found in the drinking water supplied by the waterworks in predominantly very low concentrations,” explains the Bavarian State Office for Health and Food Safety (LGL).

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People become infected with the rod bacteria by inhaling the spray of Legionella-contaminated water – for example when showering – so that the pathogens reach the lungs.

How can the risk of infection be minimized?
The Legionella concentration in cold and very hot water is so low that the pathogens do not pose a health risk. “In the warm – especially longer standing – water with temperatures between 30 and 45 degrees – they can multiply and occur in high concentrations”, warns the Building Owner Protection Association (BSB) in its guide “Legionella risk in house and apartment”. Already at Water temperatures from 50 degrees they would die off again. “A safe and, with increasing temperatures, increasingly faster killing takes place just above 60 degrees”, adds the LGL.
Consumers should therefore ensure that the tap water reaches the appropriate temperatures. This is the only way you can spread the bacteria and thus prevent an infection as far as possible.

When the risk of infection is particularly high
The authorities therefore warn against reducing the system temperatures of the in-house drinking water system. Around energy and to save costs, many people lower the hot water temperature in the warm summer months and unconsciously create ideal conditions for legionella. Even if the hot water cools down too much in the pipe on the way to the tap, it can be dangerous. “Warmed drinking water at a lower temperature is only hygienically harmless if it is heated at the point and at the time of consumption, for example using a flow heater or heat exchanger”, according to the LGL.
In addition to the temperature, standing water in particular favors the multiplication of bacteria. “The water that is in the pipeline for the last few meters before the tap is always the most polluted,” confirms the LGL. “You can reduce your risk by carefully allowing the first few liters to drain, especially if you have been away for a long time.” In addition, one should keep an eye on the water temperature, recommends the BSB. “Temperatures of 60 degrees should be maintained at the hot water outlet. The return temperature of circulation lines should not be more than five degrees below the outlet temperature. “
Drinking water storage tanks increase the risk of legionella
Oversized hot water storage tanks in which the water has been standing for too long have a potential risk. “Basically, drinking water systems should be adapted to the needs of the residents”, according to the BSB. “Above all, storage tank sizes, line lengths and tapping points should be dimensioned to match the number of users in order to avoid stagnation times.”
A heating system that can be combined with a fresh water station for heating drinking water is ideal. This device brings the fresh drinking water to the required temperature by means of a heat exchanger based on the flow principle via an existing buffer storage or directly at the heat generator, explains the BOD. A disadvantage of heating drinking water above 55 degrees, however, is the increased precipitation of dissolved solids lime. For this reason, in regions with a high lime content in the water, a softening system based on the ion exchange principle should also be operated. This supports the longevity of the drinking water system, advises the BSB. Softened water also offers legionella fewer nutrients.
Reduce the risk of legionella in existing drinking water systems
Existing systems can also be optimized afterwards. So that warm water is up to water tap If the pipe does not cool down enough to reach a problematic temperature range, you can, for example, have pipes and fittings subsequently insulated.
If the number of people living in the house is reduced, for example when the children move out, the existing hot water tank is often too large for the number of people. The BSB advises that this should be subsequently adjusted to the actual needs. For water pipes in which stagnant water can form, the experts recommend dismantling or converting them.

Legal regulations for the in-house drinking water system
The Drinking Water Ordinance sets legal requirements for the quality of tap water. According to this, drinking water must generally – even in small private households – be of such a nature “that there is no cause for concern about damage to human health, especially from pathogens, through its consumption or use. It has to be pure and enjoyable. “
In particular, “the generally recognized rules of technology must be observed” when distributing and treating water. This is another reason why planning and installation belong in the hands of specialist companies who know and can implement the applicable standards, regulations and guidelines.
Regular inspection obligations apply to all drinking water systems that have a storage volume of more than 400 liters or a flow volume of at least three liters and are also used in a multi-party residential building. Systems in one- or two-family houses are generally exempt from the obligation to examine, reports the BSB.
Landlords bear the costs for the test
For the inspection of the drinking water system, the landlord must ensure that the tenants are informed about the sampling in good time. This is because access to the apartment must be enabled in order to take the samples. The costs for the drinking water control can be claimed as operating costs, explains Haus & Grund Westfalen.

Legionella infection symptoms
Legionella infections can cause two different clinical pictures in humans: Robert Koch Institute (RKI) estimates the level of Legionella infections at up to 36 diseases per 100,000 inhabitants per year. “Since not all pneumonias are tested for a Legionella infection, an under-reporting can be assumed,” according to the RKI. The so-called Pontiac fever manifests itself through flu-like symptoms: headache, limb pain and chest pain, which are caused by fever, cough, Diarrhea and confusion can be accompanied. The disease is easily treatable. No deaths are known so far.
Legionnaires’ disease is particularly dangerous
Legionnaires’ disease (also known as legionnaires) is more dangerous because the lungs are massively affected. The disease manifests itself in the form of a severe one lung infection and is notifiable. It can even be fatal, especially in people with weakened immune systems and old age, as well as in patients with a history of heart or lung disease. The first symptoms of the disease are the same as those of Pontiac fever.