ᐅ My Wastewater System in an Old Timber-Framed House

Hello,
I took over my grandfather’s old half-timbered house in 2014. In the 1980s, my father renovated and renewed many parts. He was a craftsman and did almost everything himself. Unfortunately, he is no longer here, so I hope for your answers.

When I took over the house, the bathroom had been altered. It’s a very small room, now equipped with a walk-in shower and a toilet on the right side, and a washbasin on the left side. In the middle of the right side, the washing machine used to be placed, which had a separate drain for potential flooding. See photo.

Now I took a closer look at this open drain. You just have to remove the grate to see into a pipe about 15 cm (6 inches) deep. The pipe has a closed bottom, and it looks like no water could flow away there. When the shower runs, you can see how the water from the shower flows into this pipe from the left, but I don’t see any outlet. The floor cover has a small crack, as far as I could tell.
I’m wondering where the shower water actually goes? Does anyone know these types of pipe systems?
I’m trying to attach a photo.

The water flows over the edge. When you are close to the edge, there is an open space behind it. The structure basically has a double formwork. It is designed to catch things if they fall in while allowing only water to drain away.

Which edge are you referring to???
The water is at most 0.5 cm (0.2 inches) high when the shower is running.....

It looks like there is a large crack on the lower left side, under that strange structure on the left, over which the shower wastewater flows.
I already thought the pipe was broken. I gently pressed on the bottom of the pipe and it gave way. Help!!!!

I will try to take a look tomorrow with a mirror.
So it doesn’t matter if there is a small crack in the bottom of the pipe?
In other words, the bottom of the pipe is the normal drain, it’s just kind of secured so that hair or similar debris don’t get into the drain?

Martina,
Maybe you will get a better understanding if you search for "shower drain" on Google, then look at the images to find one that matches yours, and follow that path further.
I just came across a YouTube video about internal cleaning – very interesting and looks similar to your drain.

Alright, I’ll start looking then! Thank you!