Building application: Specify future bathrooms/kitchens?

Hello.

I am currently working my way through the building application.
We will have a small guest bathroom and our kitchen on the ground floor and the actual bathroom in the attic.

Since we are building with a basement, another bathroom with a sauna and a utility kitchen for heavy-duty use are planned there in the long term. However, these two rooms will only be built years later (connections can of course already be considered during the shell construction).

In the building application, under the drainage application, 2x kitchen and 3x bathroom are indicated.

Is that reasonable? Shouldn't only what is actually going to be done (initially) be indicated? Might I even have to expect higher sewage costs because of this? Or is it only for statistical purposes anyway?

Similar information is also included in the application for connection to the water supply.

Thanks in advance for any help.

I suspect this has more to do with the sizing of the house connection. A large apartment building certainly requires a somewhat larger connection line than a small single-family house. However, at your scale, this will probably be irrelevant. Wastewater costs are usually based on consumption, not the number of bathrooms. As far as I know, I have seen a clause in the insurance policies (building and/or household contents) that limits the number of bathrooms covered. The risk of pipe burst increases with more bathrooms than usual.

Wastewater pipes are almost always DN100. For the pipe to be larger, quite a lot must be connected. As long as only the wastewater pipes are being prepared, it probably does not need to be specified. Why would it?

In the building application, however, 2x kitchen and 3x bathroom are indicated in the drainage application for the facility.

The drainage of the house must be ensured .... regardless of the date when you build the basement bathroom and kitchen? This has exactly nothing to do with the static. Rhenish greetings

The drainage must also be approved. In a few years, it will be difficult to lay it ;(

It will not be approved inside the house. If at all, then outside. However, it would be advisable to use the same line (i.e., the same outlet to the outside) inside the house also for the basement. Otherwise, the line would remain unused and stand idle.