Parents' Bathroom Layout

Do you have a circulation?
It's not my main focus, but in the picture I think I see a circulation ... I rather consider thinner cross-sections justified when no circulation is created (3-liter rule). Why save a few euros on a larger cross-section then ...?

I mean, the Hansgrohe PowderRain was rated below 20l ...

The 3-liter rule is not relevant for a single-family house. It only applies to large systems.

The 3-liter rule is not relevant for a single-family house. Only applies to large systems.

Oh really? Everywhere on the internet it's stated differently, even in the pink forum as well as bosy, and the gentlemen there regularly carry out such things ...

The preamble was a bit wrongly expressed by me, sorry. The 3L rule only applies to large systems. According to the definition, a system is considered large if the hot water storage tank is larger than 400L OR the water volume in the pipe from the hot water storage tank to the consumer is greater than 3L. However, this rarely happens in a single-family house. For a 15mm inner diameter, that would be more than 17m of pipe length for it to apply.

I think we are talking past each other?

By the 3-liter rule I mean that no more than 3 liters of water may stand in any hot water pipe without circulation or trace heating. For reasons of hygiene. If a longer pipe is needed, the cross-section must therefore be smaller so that it stays below three liters.
The 3-liter rule is also an aspect in defining whether there is a small or large system. This may also result in the obligation for circulation. That was not what I was referring to and I think that is what you are addressing right now?

What exactly leaves you speechless? The water consumption or the discussion about the cross-section?

The discussion about the cross-section, but less about that of the pipe, and more about that of the droplets. Certainly, with an appropriate adjustable air injection just before the shower nozzles, an even finer atomizing effect could be achieved. But I personally shower with a standard showerhead, and after 10 p.m., for the neighbor's sake, even without singing – without this lack of enjoyment traumatizing me (and the cleaning effect is also impeccable). I do not necessarily have to turn a shower into a transformation of a whirlpool into flowing water.

Admittedly, the GU also said that he does not build such bathrooms often.