I want to drill a tiny hole from the bathroom into the next room. This wall has a sink and shower attached. On the other wall of the bathroom is a toilet and bath tub. Above the bathroom is another flat, which I assume has the same layout as mine. So above should be a bathroom as well (which I can acoustically confirm). I guess I share the drain with the above flat, which means my target wall most likely contains a drain going vertically from top to bottom, unless there's only one drain for the bathroom and it's on the toilet side. I guess this drawing makes the layout more clear:
I have this scanner to find electricity and water pipes, but drains are non metallic. How can I make sure not to hit the drain? The flat is in Germany.
The wall is most likely a brick wall. That's at least what I found in the kitchen. I didn't drill anything there yet, so I don't know the dust color. But the wall doesn't sound hollow.