Lisa Scholl

Lisa Scholl


Kill legionella temperature – how many degrees are necessary?

Legionella are bacteria that find ideal growth conditions, especially in artificial water systems such as water pipes, and multiply there. The pathogens can enter our lungs via the water vapor and pose a major health risk, especially for the elderly, sick and weak. It therefore makes sense to prevent the spread of legionella in one's own household with the right measures. This article shows how Legionella can be successfully controlled with the help of high temperatures and provides helpful tips for the prevention of Legionella infestation.

What are legionella?

Legionella is an infectious bacterium that can cause various diseases in humans. The bacterial pathogens are found in natural waters all over the world, but do not usually pose a threat to humans there due to their low numbers. In artificial water systems, on the other hand, the pathogens multiply rapidly under good conditions and can thus become a risk to humans.

Transmission of the bacteria from person to person is impossible, and even through drinking infected water, infection is only very rarely possible. Legionella is usually transmitted by water vapor or atomized water. The water droplets with the pathogens they contain are inhaled through the air and thus enter the lungs. Common sources of infection are therefore mainly showers, humidifiers, faucets and also whirlpools.

But how dangerous are legionella bacteria really? Especially in immunocompromised people, an infection can cause flu-like symptoms up to severe pneumonia, also called Legionella pneumonia. In order to avoid any risk of legionella, appropriate precautions should therefore be taken against the harmful bacteria.

Propagation in water pipe systems

Legionella love warm water temperatures of 25 to 45 degrees Celsius and particularly like to multiply in water pipes that have such a lukewarm temperature. Especially in coatings of the pipe system, the bacteria find ideal growth conditions and can reproduce extremely fast.

Fighting legionella – this is how it works!

A positive finding of Legionella is initially a shock. But fortunately there are some tips and tricks on how to combat the harmful pathogens. What to do about legionella? With these measures, the bacteria are combated in no time and a new infestation is prevented.

The ideal temperature to kill the bacteria

The following applies: In a residential or public building with a central hot water tank and central water heating, the permanent temperature of the drinking water heater should definitely be set to at least 60 degrees Celsius.

Water temperatures above 55 degrees Celsius do not survive legionella, which is why they cannot multiply in the central water reservoir. Accordingly, the water temperature in the entire piping system of the house at any point should not be less than 55 degrees Celsius. A temperature of at least 60 degrees Celsius should always be maintained at the outlet of the drinking water heater for reliable thermal disinfection.

Regular use of the water pipes

Water pipes remain germ-free if they are used and flushed regularly. Above all, dead lines should be avoided at all costs in the piping system of a house, because a standstill of water in the pipes favors the spread of legionella.

To ensure reliable killing of possible bacteria, all pipes can be regularly flushed with 70, but at least 60 degrees Celsius for a few minutes.

Especially in old buildings, old water pipes should be insulated if possible to prevent heating of the water pipes in summer and, on the other hand, heat loss in winter. Another option is to install a circulation pump, which will add movement to the water flow, preventing stagnant water buildup.

Optimizations of the house installations

There are a number of useful products that provide effective protection against Legionella and ideally complement thermal disinfection. Sanquell’s legionella filters have high-quality membranes with ultra-fine pores that safely and reliably filter legionella from drinking water.

Legionella filters are particularly effective in the shower, where the risk of infection is very high. A filter for the faucet is also recommended.

Important: All products should meet regulatory standards and comply with the TWIN standard to ensure reliable purification of water. In addition, they should be cleaned and replaced regularly to ensure their hygiene and effectiveness.

FAQ: Kill legionella with high hot water temperature

How fast do legionella die at 60 degrees?

The Federal Environment Agency recommends regular flushing of water pipes with a hot water temperature of at least 60 degrees Celsius to combat legionella. At this temperature, Legionella cannot survive and die within two minutes.

It is even better to heat the water temperature to 70 degrees Celsius. Here, the bacterial pathogens already die reliably within a few seconds.

What should be the temperature in the hot water tank?

Ideally, the temperature in the entire hot water system of a house should always be above 60 degrees Celsius. Temperatures of up to 70 degrees Celsius are even best suited to reliably kill all vital Legionella.

The following applies: To prevent the spread of bacterial pathogens, nowhere in the entire hot water circuit should the hot water temperature be below 55 degrees Celsius.

How to kill legionella?

Legionella is most effectively killed by high water temperatures. The principle of thermal disinfection works quite simply: from a temperature of 55 degrees Celsius, the bacteria can no longer multiply and spreading is prevented.

It is even better to use a temperature of at least 60 or even 70 degrees Celsius. This ensures that even vital Legionella bacteria are reliably eliminated.

How long should you run water against legionella?

How long the water pipes have to be flushed with hot water to achieve complete thermal disinfection depends on the respective hot water temperature. The following applies: At 55 degrees Celsius, several hours are required to reliably kill all bacteria. At a temperature of 60 degrees Celsius, a few minutes should be enough.

By raising the temperature to 70 degrees Celsius in the entire hot water system, just a few seconds are enough to ensure effective killing of the vital Legionella bacteria.

Conclusion – the bacteria are sensitive to high temperatures

Legionella are harmful pathogens that can enter the lungs via water vapor and cause disease. Fortunately, bacteria can be reliably controlled with the help of thermal disinfection at temperatures above 60 degrees Celsius.

Protection against the pathogens is even more effective if several protective measures for legionella prophylaxis are used in combination. In addition to thermal disinfection, it is recommended to install high-quality legionella filters for the shower and faucets – these filter the harmful bacteria from the water and ensure that clean and hygienic water flows from the pipes.


Legionella: How long to run water?

Legionella can be found wherever there is water. These are rod-shaped bacteria that reside in freshwater and multiply intracellularly depending on the water temperatures prevailing there. The ideal conditions for Legionella are at temperatures between 25 and 50 degrees and in surfaces wetted with water, such as water pipes, fittings or even air conditioning systems.

Especially in older, poorly maintained or even little used water pipes there is an increased risk of legionella. However, calcification or materials such as rubber or plastic can also promote legionella proliferation.

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How quickly do legionella form?

Legionella are basically found wherever there is fresh water – so they are an integral part of our drinking water in small numbers. Nevertheless, legionella can pose a threat to human health, as they can cause severe pneumonia, among other things, if they become infected.

If the external conditions are optimal for Legionella growth, they can multiply rapidly. But what exactly are legionella? How are they transmitted and how fast do pathogens actually multiply in drinking water? All this and how to protect yourself from the dangers of legionella, you will learn in this article.

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