Rainwater drainage from the property

if you want us to help you, you have to give us some information. why is the ground not suitable? a soakaway basin is the cheapest infiltration method (unfortunately often also the ugliest), since basically hardly any excavation work is required.

is the groundwater too high now (what depth?) or is the soil impermeable? why should it work better about 30 meters away (how big is the property, please?)?

Edit: just read the excerpt from your reports.

then a larger "container" connected to a trench soakaway would be suitable. the infiltration would be "slow" but still present. the storage takes up the water and releases it gradually. it should be possible to do it for significantly under €20,000.

if a soakaway basin works, I would take that. then you only have to lay a "few meters" of pipe from the house to the soakaway basin (it is only 20-30 cm deep). that would be very attractive price-wise, but you have a relatively large depression somewhere on the property.

All you can say to that is "tough luck," and you ran into a typical civil servant... you really shouldn't have sent the report along. According to DWA leaflet 138, which the processor refers to, infiltration is simply not possible, especially if the groundwater is higher than about 2m. Your neighbors probably just gave lower values (lied), because practically it does work...

The alternative is a large cistern; the garden alone is not enough to get rid of the water, so you have to connect the toilet and washing machine as well. The problem still remains as to where the water from the emergency overflow is supposed to go.

Der Bauträger sagt:

Do you mean a GÜ? With a developer, you would have the right to a free-of-encumbrance, functioning house and would not have to deal with the details of infiltration.