Routing of pipes from the utility room to the bathroom

I think we are currently misunderstanding each other. I might also be using the wrong terms. From the bathroom to the downpipe, the wastewater pipe must have a certain slope. This section is the problem. I can't imagine that the pipes on the upper floor go directly outside...

I think we are misunderstanding each other right now. Maybe I am also using the wrong terms. From the bathroom to the downpipe, the sewage pipe must have a certain slope. This section is the problem. I can't imagine that the pipes on the upper floor go directly outside...

However, the downpipe does not have to have any contact with the utility room. That is what this is about. It is about the lack of "contact" between utility room/bathroom It is not about "how is it done in the bathroom?"

Ok, now I understand you.
That is of course true. The bathroom and utility room do not necessarily have to be adjacent or connected.
I quickly looked at the floor plan of Lindenallee.
I suspect that the wastewater either goes out in the technical room (utility room) or in the WC. The bathroom on the upper floor is on the other side. As you already wrote, the drain thus runs through the living area.

We have, for example, two wastewater pipes in the house...

but the drain runs through the living area at Lindenallee

Uh, yeah, I agree - but when did Lindenallee come into play? - I must have missed when the OP switched to "with attic" (?)

Was in the first post that was edited due to a forbidden link