Heute  Gutscheincode eingeben, 5% Sofortrabatt sichern

Lisa Scholl

Lisa Scholl


Legionella – what to do?

Legionella are bacteria that are found in water pipes and can cause severe illness in humans. When an infestation has been detected during a legionella inspection in a building, it is important to act quickly and appropriately. Measures must be taken to minimize the risk of infection and protect the health of owners and tenants. In this article, we will share with you the most important steps you should take if you have been found to have Legionella.


What are legionella?

Before we turn to the measures that should be taken in the event of a legionella infestation, it is first important to understand what exactly legionella is all about. Legionella are bacteria that can be found in surface water, but also in water pipes. They multiply particularly well in warm water – for example in showers or air-conditioning systems – and enter the indoor air via water vapor, among other things.

If these germs are now inhaled, they can cause pneumonia and other infections. The elderly, smokers and people with weakened immune systems are particularly at risk. The best known disease caused by Legionella is Legionnaires’ disease. This can be accompanied by severe pneumonia and in some cases can be fatal.

A legionella test provides clarity

A legionella test can provide clarity as to whether or not a house is affected by legionella. Especially in apartment buildings, it is important to regularly perform a legionella test to protect the health of the residents. If a Legionella infestation is detected during such an examination, appropriate measures should be taken immediately to minimize the risk of infection.

For information on the required steps, see the following section.

Legionella – Measures in case of infestation

If an infestation has been detected during a legionella test, quick action is required to protect the health of the residents. This article aims to provide those affected with a checklist of the most important measures to take. These can be worked through step by step in the event of a legionella infestation.

The first steps

It is important that all residents, users and owners are immediately informed about high legionella contamination of the drinking water installation and that basic rules of conduct are communicated to them. A Notice of positive legionella findings or a Notice shower ban are necessary for this.

This includes avoiding activities that finely atomize hot water and create aerosol formation (tiny droplets of water in the steam). In addition, before starting the shower, the hot water that collects should be drained off, if possible, in such a way that no aerosols can form. Deposits of lime and traces of corrosion should be thoroughly removed, as they can promote the growth of pathogens.

Only packaged water should be used for cleaning medical devices, respiratory or air humidification, and inhalation. Immunocompromised individuals or residents with pre-existing conditions should seek further information from their physician.

To be safe, use a legionella filter to prevent infection.

Hazard analysis

A hazard analysis in case of detected legionella infestation aims to determine the extent of contamination and the associated risks to the health of the occupants or users of the affected building. For this purpose, the concentration of legionella in drinking water and in the air is measured and evaluated.

Based on the results of the hazard analysis, targeted measures are then taken to minimize the risk of infection and make the drinking water safe again in accordance with the Drinking Water Ordinance.

Flushing and disinfection of the lines

To reduce the concentration of legionella in the pipes, it is necessary to perform flushing and thermal disinfection. In this process, the pipes are flushed with a high temperature of at least 70 degrees Celsius to kill the environmental germs. Flushing the shower is particularly important, as there is an increased risk of legionella infection here due to the finely atomized water.

Additionally, chemical disinfectants may also be used to ensure complete elimination of Legionella. However, the choice of the appropriate disinfection process depends on several factors, such as the type of piping and the level of contamination, and should be performed by a professional.


After performing the steps to control legionella infestation, it is important to perform a follow-up inspection. This will ensure that the problem has been fully resolved. For this purpose, a second legionella test is carried out, during which samples of the drinking water and the air are taken again to measure the concentration of legionella.

If an elevated concentration persists, further action may need to be taken. If, on the other hand, all values are within the normal range, it can be assumed that the measures were successful and there is no longer any danger to the health of the property’s occupants.

Inform competent health authority

If a legionella infestation is detected, the responsible health authority must be informed. The latter can recommend further measures and, if necessary, also inform other affected facilities in the vicinity to prevent spread. In addition, the Authority may receive complaints from tenants and other affected persons and refer them as necessary.

A transparent information policy is an important step in protecting the health of all stakeholders.

Find responsible health office

Prevention measures

Various measures can be taken to prevent legionella infestation. One option is to raise the hot water temperature to at least 60 degrees Celsius, as this prevents legionella from multiplying. In addition, special legionella filters can be used in the shower or bathtub to prevent contamination.

Regular descaling and cleaning of shower heads and hoses can also reduce the growth of Legionella. Furthermore, it may be useful to carry out regular legionella testing in order to detect contamination at an early stage and take countermeasures.


The topic of legionella raises many questions – we have the answers for you.

If a legionella infestation is detected, the affected pipes should be flushed and disinfected immediately. Furthermore, informing affected individuals and tenants is a top priority. Subsequently, the relevant health authority should be informed and a follow-up investigation should be carried out. Until an all-clear is given, provide those affected with Legionella filters.

Legionella can be removed by flushing and disinfecting the affected pipes. To do this, the affected water must be heated to at least 60 degrees Celsius. Special chemical disinfection methods can also be used for stubborn infestations.

The most important step is to avoid all activities where hot water is finely atomized and aerosolized – such as showers or bubble baths. It is also advisable to inform the competent authority immediately.

After a positive legionella finding, the temperatures in the affected piping system should be increased to at least 60 degrees Celsius or the entire system should be disinfected. After completion of these measures, a new examination for legionella infestation must be carried out.


In the event of a legionella infestation, it is first necessary to inform the residents immediately. Legionella filters protect against unpleasant consequences.

After that, steps such as rinses and disinfections should be performed. Preventive measures such as regular maintenance and appropriate temperature settings can help minimize the risk of Legionella infestation.


Safe and immediately protected against legionella.

The best-selling legionella filter.


Legionella filter shower – advantages and operation of the filter system.

Drinking water in Germany is subject to strict quality standards and can generally be used without hesitation, both for consumption and for personal hygiene. In some cases, however, hot drinking water from the tap or shower can also be contaminated with harmful bacteria – the so-called legionella.

This article shows why the use of a legionella filter makes sense and which types of filters can be used.

Weiterlesen »
Filter water

Finding the right faucet – This is what matters

If the existing faucet needs to be replaced, or in the course of new construction, builders decide to install the faucets themselves, sooner or later the question arises: How to fix a faucet in the kitchen or bathroom?

But do not worry: installing a faucet is anything but laborious or complicated. But how to find the right faucet, why is the planning phase crucial and how to turn on the new faucet? This article provides step-by-step instructions for beginners!

Weiterlesen »

Persönliche Beratung

Du hast noch Fragen, die du lieber direkt klären möchtest? Dann buche jetzt einen Termin mit unseren Wasserfilter-Experten. Jetzt Termin mit Lisa buchen