Do the building laws apply equally to the municipality?

how I can find out whether there is now a public interest here u

The fire protection also decides that. And fire protection is so important in residential buildings that you almost have to do everything the fire department says.

But where can I read which rules apply here?

As a private person, you will not find all the rules. Even I cannot tell you, although real estate has been my profession for 30 years.

But where can I read which rules apply here?

Just google for sovereign tasks and the whole rat’s tail.

whether there is a public interest here

Certainly.

this is also weighted more heavily,

Always.

The lack of firefighting water was the main reason why our building permit was denied.

Then you have chances if the firefighting water is provided.

To my knowledge, underground buildings do not require a setback area. I strongly suspect that the tank will be placed underground?

To my knowledge, underground buildings do not require setback areas. I strongly suspect that the tank will be placed underground?

Yes, it is supposed to go underground. Do you have a source for your knowledge?

I would first look in the state building code. I don't know your federal state, so I can't say anything specific. I believe it is not explicitly stated, but follows from the requirements for spacing rules, which only apply to above-ground buildings. Ergo, there are none for underground ones. However, I am not sure if that is the same everywhere.

To assess whether there is a chance for a building permit here, one would need to see the neighboring buildings, preferably as a Google Maps snippet. If you are somewhere on the edge, it looks bad. Otherwise, the timing might be favorable to submit a preliminary building inquiry. It is important to include all necessary commitments for development. So water, electricity, sewage, road, fire department, nature conservation balance, integration into the neighboring buildings, etc. - the whole rigmarole.