Drainage - "Water Law Permit"

Hello,

the following situation: We need a "water law permit" from the city for our construction. Due to difficult soil conditions, a soakaway shaft is not permitted and has already been rejected (groundwater at ~3.0m). Now we have the following alternatives: - A pipe infiltration trench with a length of at least 3.5 (cross-section 1x1m) - A DN 200 soakaway pipe with a storage coefficient of 0.37 (a soil replacement up to the existing gravel layer is necessary) - An infiltration basin with 1 m³ per 100m² of roof area (which applies to us) Since we unfortunately have absolutely no idea which option we prefer, I would be very grateful for information (especially regarding prices). The problem with the basin is that we don't have the largest garden.. but visually there is no objection!

Thank you.

A few years ago, we installed a cistern because we wanted to save the costs of rainwater disposal. Therefore, this cistern must not be connected to the drainage pipe, and we had to figure out how excess water could be "disposed of" on the property. A swale is not possible due to too many trees and so on standing here. For underground disposal, a permit from the lower water authority is required here (NRW). The inquiry about whether it is feasible or not already costs 100 €. However, if the water is allowed to infiltrate the surface, it can be done easily. The decision was then clear to allow the water to infiltrate on the surface. For this purpose, simple HT pipes were used, slits were cut into them, and the pipes were then connected without sealing and placed far enough from the neighboring property. By slitting and not using seals, the pipes can also be rotated, ensuring that water can flow out more or less evenly along the entire pipe length. These pipes can be nicely camouflaged with ivy or other plants. However, we still need a pump to pump the excess water from the cistern into this pipe.