legionella

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Updated on: 04/28/2020

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The star among the water germs

Legionella are bacteria that can be found in tap water, but also in compost or in air conditioning systems. As pathogenic germs they can cause life-threatening pneumonia (legionellosis) and other diseases. The so-called "legionnaire's disease" is caused by legionella. Infection occurs through direct contact with bacteria in the form of a droplet infection, for example when hot water mist is inhaled while showering.

Legionella and rod bacteria at a glance

Due to a high mortality rate for infections of 10 to 15 percent, it is estimated that up to 3,000 deaths per year occur in Germany.1 There is no exact case number; the Robert Koch Institute assumes 1.8 cases per 100,000 inhabitants. Since many pneumonia cases resulting from Legionella infections are not recorded as such, a high number of unreported cases can be assumed. Particularly treacherous are the initially unspecific signs of illness such as high fever and chills, which do not immediately indicate a legionella infection. Protective measures are therefore necessary. But how effective are legionella filters and other precautions?

Why and how do Legionella bacteria develop in the water pipe?

Legionella are so-called environmental germs that occur in surface waters, but also in groundwater. In addition, humid biotopes such as mixed soil or humus play a role. They are a natural component of nature. As infectious pathogens, they cause problems especially in technical facilities such as drinking water systems. The Robert Koch Institute mentions water temperatures between 25 and 45 degrees Celsius as optimal growth conditions for legionella. It is particularly dangerous in water containers with standing water that reaches these temperatures. Deposits such as lime and, above all, the biofilm that develops in pipes also play an important role in the development of a danger from Legionella. It consists of bacteria and organic substances. 

Legionella and rod bacteria at a glance

Enterococci

Enterococci are also an indication of contamination of drinking water by faeces. The introduction of such bacteria into groundwater can be caused by agricultural fertilisers or the faeces of farm animals; precipitation transports them into the groundwater. However, technical faults in the sewage treatment plant or repair work in the public pipeline network can also introduce enterococci into the drinking water.

Enterococci can lead to infections in various parts of the body, especially the urinary tract, but also the abdomen and heart, in people with weakened immune systems. In women, this can lead to inflammation of the fallopian tubes or infection of the bladder. Wound infections and abscesses are also among the possible consequences.

How does Legionella infection occur?

Only in exceptional cases is infection caused by drinking contaminated water. Dangerous is rather the water mist that can emanate from hot water. It is used to inhale the smallest water particles, so-called aerosols. If these aerosols are contaminated, a dangerous disease can result. This happens very easily in the daily shower. However, there are a whole range of other sources of danger where infection with Legionella is possible. For example, such a spray can occur in whirlpools or on water slides in swimming pools, but also in connection with medical treatments, for example in a dental practice. Leaking pipes are also a source of danger. Many people become infected when travelling, for example if hygiene regulations are not observed at a holiday resort or camping site. Contaminated water is always a danger. In technical terms, this is referred to as an illness acquired on an outpatient basis. This includes 75 percent of all infections. A further spreading from person to person does not take place. Major outbreaks are therefore rare. However, there are signs of an increase in infections since the introduction of the obligation to notify in 2001. Climate change, with higher temperatures and heavy rainfall events, could play a role here, since heavy rainfall in particular leads to water contamination.2

Steam in the shower

How can you kill Legionella?

Legionella can be killed mainly by high temperatures. The bacteria cannot survive at temperatures above 60 degrees Celsius. Flushing water systems in buildings with hot water is therefore an option. It is carried out by companies that specialise in handling the Drinking Water Ordinance in order to minimise liability risks for property operators. However, there are studies which indicate that Legionella bacteria can survive higher temperatures for a certain period of time, which casts doubt on "thermal disinfection".

Another method is the use of chlorine, which, however, must be used in large quantities to effectively remove the biofilm in pipelines.

For the consumer, the proper use of water filters against Legionella is the safest way to protect himself.

Checklist: Measures in use against Legionella  

  • Officially prescribed measures:
    - Flushing of water systems and pipes with at least 60 degrees hot water
    - Flushing of water systems and pipes with large quantities of chlorine
  •  Consumers:
    - Use of water filters

What does the landlord have to do with Legionella? 

The danger from legionella means far-reaching obligations for landlords. In 2011, the Drinking Water Ordinance set a limit for legionella, which is 100 legionella per 100 millilitres of water. This means that operators of drinking water systems, i.e. also house and property owners, are obliged to carry out regular inspections. Almost all apartment buildings in Germany are affected by the regulation, and it covers all systems in which "fogging of drinking water occurs". The test must be carried out by an "accredited laboratory". The exact conditions and the prescribed numbers and intervals of such tests can be found in the current Drinking Water Ordinance. This is subject to regular amendments.3

When is the use of legionella filters useful?

Despite regular checks and preventive measures against the formation of legionella - such as thermal disinfection or chlorination of the water - the use of a legionella filter is a useful protection. It should be used wherever drinking water is misted, for example in showers or whirlpools. As an additional protective measure, it is also appropriate where there are persons with an increased risk. Especially for elderly people and people whose immune system is damaged, a legionella infection can be fatal. Nursing homes in particular should therefore pay special attention to the safety of their drinking water.

How effective is a legionella filter?

There is a wide range of water filters that promise protection against germs, including legionella. In order to make this protection measurable, there are a number of criteria which are also prescribed for Legionella filters in the form of technical standards. The water they filter must meet the international standard for sterile filtered water. It is crucial that the bacteria do not enter the air with the water. For this purpose, the membrane of the water filter for legionella must have a very small pore size, which is smaller than the size of the bacteria.

A criterion for the quality of a legionella filter are the 8 log levels used in the course of a filter validation. This is a mathematical procedure. For example, a log reduction of 1 - 90 percent reduces the number of germs, i.e. 100,000,000 microorganisms are reduced to 10,000,000. With Log6, one already has a reduction of 99.99 percent, which still corresponds to a number of 10 microorganisms at the initial size of 100,000,000. At the highest level Log8 there is then only one single germ left.

However, the technical quality of the filter is also very important, because it must function permanently under stress. The design must be such that leaks are excluded. The consumer must know which maintenance intervals, for example replacement of cartridges, are necessary to guarantee the protective function of the filter.

What types of legionella filters are available?

Despite regular checks and preventive measures against the formation of legionella - such as thermal disinfection or chlorination of the water - the use of a legionella filter is a useful protection. It should be used wherever drinking water is misted, for example in showers or whirlpools. As an additional protective measure, it is also appropriate where there are persons with an increased risk. Especially for elderly people and people whose immune system is damaged, a legionella infection can be fatal. Nursing homes in particular should therefore pay special attention to the safety of their drinking water. 

In practice today, various types of filters are used as legionella filters. The main ones are membrane filters and filters whose function is based on reverse osmosis. In addition, legionella filters are differentiated according to their place of use: There are special filters for the shower, which may already be integrated into the shower head, as well as independent fittings or filters for the tap. The decisive factor is that a legionella filter has the special properties that guarantee reliable filtration of pathogenic germs. It is very important to use the correct replacement filter cartridges that guarantee the reduction standard Log6 and to clean the legionella filter regularly. So-called ion exchangers and ordinary table-top can filters do not provide protection against legionella or other microorganisms. A water filter that is to be used for protection against Legionella must be tested and certified, i.e. it must have undergone a so-called filter validation.

Alb Filter NANO - safe showering and drinking

Whether preventive or in case of a positive legionella finding: Continuous filters from Alb Filter in combination with the cartridge NANO - mounted at the place of withdrawal - ensure safe showering without great effort even with tap water contaminated with legionella and other germs.

Alb filter nano. Legionella and germ filter.

bottom line

Legionella are dangerous germs that represent an underestimated danger when they come into contact with water. In addition to measures prescribed by the authorities, which have to be carried out by building owners, property operators and landlords, special water filters for Legionella offer the consumer protection possibilities. The water filters can also have other functions, such as descaling, but they must first and foremost meet fixed technical standards to reliably guarantee hygiene safety.

References

  • https://www.merkur.de/lokales/bad-toelz/heissem-wasser-gegen-legionellen-3705881.html
  • https://www.rki.de/DE/Content/Infekt/EpidBull/Merkblaetter/Ratgeber_Legionellose.html#doc2387614bodyText18
  • https://www.legionellen-zentrum.de/untersuchungspflicht-legionellen-1/grenzwerte-trinkwasserverordung.php
  • http://www.mpl.loesungsfabrik.de/faq/filtervalidierung-wissenswert/bakterienrueckhaltetest-astm-f838-15a