Surface water - Complaint of the neighbors

Hello,
my name is Thomas, I am 35 years old and live with my wife and child in Oldenburg (Lower Saxony).
I don’t know if I am in the right place here. If not, please move it.
We have a question,
two years ago we bought a plot of land and built a single-family house on it. Everything went very well.
The problem we have is the following: Before the land was developed, the surface water from the neighbors flowed onto the undeveloped plot and seeped away there. Now our house is there and the driveway is paved, etc. And the water no longer flows to us or stays as a large pond at the neighbors. They are now complaining.
How should we behave?

Thank you very much for the help
Thomas

Ignore...everyone has to make sure that the water stays on their own property. So if you haven't just laid the pavement with a slope towards the neighbor, you're in the clear. Since the surface water will mainly occur after rain...

Which water is standing as a lake at the neighbor's? Is it a) his own rainwater from his paved area or b) your rainwater that flows from your property onto his property?

Do you perhaps have a photo?

So our driveway does not slope towards the neighbor. It is the surface water from the neighbor's shed which he simply directs into a rain barrel and when it is full he opens a tap and lets the water run into the garden through a hose. Previously, it then ran onto our property (which was grass before) and seeped away there.

You have to ensure that your water stays with you and either infiltrates or is collected and discharged. The same applies to your neighbor and their water.

If they were previously able to drain water across your property, that was their advantage. However, this does not create any entitlement; on the contrary, they must now ensure that nothing flows onto your land. They will not be able to avoid drainage, etc.

He can no longer drain to us because we are now higher than him. Our water flows forward into a [Gully].