Drainage on your own property, NRW - Tips?

Hello everyone, I hope this is the right area for my question.

The drainage (regarding rainwater) of our neighboring property is currently causing us concern. Both properties are located on a slope, we are lower. The neighbor's house is currently under construction (shell construction completed) and has, with the directly adjacent garage, an estimated roof area of about 130m².

According to the neighbor, this area is simply drained on their own property. That means the downpipes, some of which are also close to our property, have no connection, neither to the local sewer system (separate system) nor to a cistern.
We are now somewhat worried that such a large roof area, drained through a few downpipes, can lead to a lot of water in just a few spots and thus can also flow onto our lower-lying property.

Additionally, I think I once heard something about a "connection obligation." When I searched for it, I found the following in the local statute:

§ 9 Connection and Usage Obligation
(2) The connection user is, subject to the restrictions in this statute, obliged to discharge all wastewater (sewage and rainwater) generated on their property into the public sewage system (usage obligation) in order to fulfill their wastewater transfer obligation according to § 48 LWG NRW.

And in case one is exempted because they want to use the rainwater:

§ 11 Use of Rainwater
If the property owner intends to use the rainwater generated on their property, they must notify the municipality. In this case, the municipality exempts them from the transfer of the used rainwater under the conditions of § 49 para. 4 sentence 3 LWG NRW, provided that proper use of the rainwater on the property is ensured and an overflow to the public sewer exists, so that flooding of neighboring properties by rainwater can be excluded.

Do I understand that correctly that there are only two possibilities, namely:
1. Normal connection to the sewer system
2. In case of exemption/usage in your own garden, a cistern with overflow, which is then, in turn, connected to the sewer system

I do not want to come across as preachy to the neighbors and point out "you, you, you" about something. Do you have any suggestions on how to best handle something like this? Also, I want to check with you again regarding this question, whether what I understood is even correct.

Do I understand correctly that there are only two options, namely: 1. Regular connection to the sewer system 2. In the case of exemption or use in one's own garden, a cistern with overflow, which is then connected to the sewer system

Yep

Hello Wissi

During a "heavy rain" a lot of water falls in a short time. With this kind of drainage, your property will turn into a torrent. Explain this to the neighbors in a friendly conversation. Also mention that the building regulations do not permit his chosen system and that in the event of water damage the insurance will come directly to him with recourse.

Steven

I would be very surprised if your neighbor has obtained a building permit for this form of "non-drainage," as the building application must include compliance with drainage requirements and the water authority checks this. Three scenarios arise from this:

[*]The procedure is as your neighbor says and approved --> unlikely
[*]The procedure is as your neighbor says and not approved --> I would advise him that he cannot move in if the building is not accepted
[*]The procedure is not as your neighbor says and he simply does not realize what is actually planned.

When addressing the neighbor, I would therefore not emphasize my own concern about flooding, but rather warn him of his own impending trouble.

Thank you for the answers so far, then I must have understood that correctly. Hopefully, this can be resolved without much fuss. Unfortunately, there have already been some issues in the past on the construction site regarding our property that were not quite right, and we had to raise concerns.

It would surprise me greatly if your neighbor received a building permit for this form of "non-drainage," since the building application must include compliance with drainage requirements, and the water authority checks this.

Our neighbors are building without a building permit (red dot), but only with the notification procedure, so the green dot. I believe with the latter you (almost) do not have to submit any plans or applications. We know this from our building application as well, with the drainage plan that had to be approved. That is why I was surprised that they plan to do it this way.

Our neighbors are building without a building permit (red dot), but only with the notification procedure, i.e. the green dot. I believe that with the latter you (almost) don't have to submit any plans or applications.

He still has to submit a drainage application and have it approved.