Some people do this by regulating the temperature for hot water preparation. This means noticeable savings can be made quickly without sacrificing comfort. But be careful: If the temperature falls below a certain level, the risk of a rapid multiplication of Legionella and thus health risks increases.
Legionella bacteria multiply in water
Legionella are environmental germs that are widespread worldwide and, in small numbers, are a natural component of surface water and groundwater. But legionella can also multiply in water points in the house or apartment under appropriate circumstances and cause illness. The pathogens enter the body through atomized, misted water, which can be inhaled via droplets in the air. This can happen, for example, in the shower, through humidifiers or taps.
Infection is possible even when drinking if the contaminated water into the lungs through accidental swallowing .
“If the hot water supply in the house is set too low, there is a risk that Legionella can spread rapidly. Legionella finds the best conditions for reproduction at 25°C – 45°C
Sascha Beetz, consultant for climate protection, energy and sustainability at the Schleswig-Holstein Consumer Center (VZSH)
In immunocompromised people, an infection can lead to feverish infections with flu-like symptoms and even severe pneumonia. If the contaminated water is used to prepare food, there is usually no danger.
The right temperature protects
In order to prevent Legionella from multiplying, a temperature of 60°C in hot water tanks and a temperature of 55°C at the drinking water tap points should not be fallen below. A so-called “Legionella circuit”, which briefly increases the water to 70°C but then drops it below 60°C, cannot stop the proliferation of Legionella.
“If a tenant notices that the temperature of the hot water at the taps is only lukewarm, they should point out the risk of legionella to the landlord,” advises Beetz. The water from central hot water systems with a storage capacity of 400 liters or more must be tested regularly. However, in apartment buildings whose apartments have their own boiler or instantaneous water heater, the risk of legionella is lower.
Sascha Beetz, consultant for climate protection, energy and sustainability at the Schleswig-Holstein Consumer Center (VZSH)
Avoid standing drinking water
In addition to a reduced temperature, stationary water in the pipes also promotes the proliferation of harmful bacteria. This particularly affects tapping points that have not been used for a long time, such as outside taps or tapping points in holiday homes, bathrooms for guests or in empty apartments. From there, dangerous germs can migrate into the entire pipe system.
To minimize the risk of spread, consumers can disconnect unused pipes from the rest of the pipe network or flush the pipes regularly. If you return to your apartment after a weekend trip or other short trip, you can flush the water pipes by opening all the taps one after the other until fresh, cold water comes out of the tap.
With a central hot water supply, circulation pumps often ensure that warm water is quickly available at the tap. The constant circulation of water hinders the formation of biofilms on the walls of the water pipes and thus prevents Legionella from multiplying. The VZSH therefore recommends not limiting the running time of the circulation pump for hot water preparation.
“If you are traveling for several weeks, it is worth turning off the water pipes at the main tap.”
Sascha Beetz, consultant for climate protection, energy and sustainability at the Schleswig-Holstein Consumer Center (VZSH)
Expert tips
To avoid health risks, you should heed the following rules:
- No lowering of the domestic hot water temperature to less than 55°C at the tapping point and 60°C in hot water storage tanks.
- No complete or temporary shutdown of circulation pumps.
- No installation of so-called Legionella circuits.
- No temporary switching off of drinking water heating.
“The best rule for saving heating energy when using hot water is: 'Use less hot or cold water. Every degree less saves costs'”.
Sascha Beetz, consultant for climate protection, energy and sustainability at the Schleswig-Holstein Consumer Center (VZSH)
Source:
Schleswig-Holstein consumer advice center
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