Lower the hot water temperature in the single-family house

On the one hand, there is a linking prohibition here, on the other hand, I find it difficult to provide proof. See it this way: The legislator requires the legionella program from a certain system size. Just read this regulation and draw conclusions from it whether it applies to you or not. I have never had a legionella program and would not even think of it. However, it is more important to lower your storage temperature at all. You don’t have to store 300l of hot water at >45 degrees (legionella program or not).

Google it. The first entry says that Legionella bacteria multiply well in standing water at 20-55 °C. So it should be completely irrelevant whether you lower from 50 to 45 °C. Both are within the range, and the problem still only arises with stagnant water.

I'm still not really convinced. For example, what exactly is standing water? If the tank has 300L but I only shower 150L every day, there is always residual or standing water left in the tank. When you read around on Google, for example the statement from the UBA, it doesn't all sound so easy with the 45°.

What, for example, is standing water? If the storage tank has 300L but I only shower 150L every day, there is always remaining or standing water in the tank.

There is practically no "standing" water in the tank with regular use. Cold water flows into the tank at the bottom, warm water flows out at the top. This always results in proper mixing.

Well, then take a good look ;)

Avoid standing, warm water
It becomes dangerous when larger amounts of water are stored for a long time at 30 to 50°C, without new, cold fresh water flowing in to replace it. This can occur in drinking water tanks or pipes if no warm water is drawn for an extended period of time. Problematic are, for example, branch lines and apartments that remain empty for a longer time.

So, even in your single-family house the water is stored for a longer time, but due to the regular usage because of showering and so on, cold fresh water always flows in again.

In the heating and sanitary group in FB there was recently a post, there was a study that proves that at 50 degrees there is an immediate stop of Legionella formation and it is unproblematic in large multi-family houses. Therefore, everyone should turn down their hot water. The next 100 posts were then conspiracy theories about the federal government.

I turn our hot water.mi