Is it possible to connect the kitchen wastewater to the downpipe?

Then you have to lay the pipes inside the house (in the floor or in the basement) to the other side and drain them into the disposal channels there.

Somehow I don’t really like to believe that a proper plumber connected that to the downpipe.
Honestly? I’d rather guess it was the "marriage plumber".

Hello,

we also used this type of "pipe" for our new building. However, exclusively as "protective casing" for our fresh water pipe, the power cable, and the telephone cable.

As a drain pipe, I find, as a layman, this pipe somewhat borderline.

What you should also consider: If you lead your wastewater through the exterior wall and connect it to the rainwater downpipe outside, in my opinion, there are two risks:

1. Thermal bridge into the house

2. Risk of freezing - if it gets really cold in winter, the pipe might freeze - you can surely imagine the consequences.

Therefore, I share the opinion of : Either lay the pipe in the floor (provided the screed thickness allows it) or down into the basement and connect it there under the ceiling to the existing wastewater pipes.

Regards,

Dirk

Well, that was a real plumber who charged us a lot of money for moving the kitchen. All the water connections had to be relocated, after all. The question remains: Can I somehow "get" him for that? I don't think so! :-/