Type of surface water infiltration

In the development plan for our property, there is a section on surface water.

It states that the rainwater that accumulates is either to be used as service water or, as far as possible due to the given soil conditions, to be infiltrated.

No type of infiltration is prescribed.

A future neighbor then asked us how we plan to drain, and showed us a text which was a drainage concept specifying infiltration types (swale or trench) for individual properties.

This confused us a bit because until now we assumed that such things must be specified in the development plan.

Are we correct in this understanding?

What kind of document is this exactly? I would build a cistern and connect the emergency overflow to an appropriate infiltration system.

Calculate based on the roof area and planned use for the manufacturer cistern and infiltration, e.g. infiltration tunnel.

You get something out of the cistern (garden water), and the area for infiltration is fully usable and even drivable with >50cm soil coverage, even with plastic infiltration tunnels.

Not significantly more expensive than a basin, but in my opinion much less obtrusive.

He said something about the drainage concept of the municipality. The only thing I found about it is a reference in the justification for the development plan, which refers to an appendix titled: Preliminary rainwater disposal concept for the development plan. However, the concept cannot be found anywhere.

I am only concerned with whether it can be prescribed which drainage must be used on one's property.

Until now, I was under the impression that this must be stated in the [Bebauungsplan].

You can also be told what you are allowed to build on your property.
I would suggest asking the municipality.
I am more familiar with it being required only to prove that the infiltration meets the requirements.