Rainwater from the roof - drainage in the soil for discharge?

Hello, we are currently in the construction phase of a single-family house and I am considering where to direct the rainwater from the four downpipes. Generally, there seem to be no major problems in the area with rainwater infiltration. We also do not have a basement.

I must also say that I am a beginner in gardening. So please do not take my questions the wrong way.

According to the soil survey, the groundwater begins at about 3.80 m. Therefore, we wanted to install a water pump (lower costs due to shallow drilling depth) and thus a cistern as a water storage is probably rather pointless.

Now I was thinking of installing 10m drainage pipe on each of the 4 roof downpipes, buried in the ground. Of course, surrounded by gravel or fleece.

[*]Is this overdimensioned?
[*]Should the end of the drainage pipe be left open so that water does not back up visually in case of larger volumes and the gutter does not overflow?
[*]Do you see any problems with this plan?
[*]Should I always install a backflow valve at the beginning of the drainage pipe so that water does not overflow the gutter? But then, in an extreme case, the water would run down from the roof because the backflow valve does not let water pass downwards.
[*]Do you have other suggestions?
[*]Am I just worrying too much about the rainwater?

Thanks in advance for your help/tips.

Attached are further data from the soil survey:

"Bodengruppe SE->highly permeable/OH->permeable: Thus, the sands beneath the topsoil or the filled sands have very good infiltration properties up to the respective groundwater level."

"Furthermore, it is pointed out that in the construction area, due to a reduction in groundwater extraction by the surrounding water suppliers in the future, the groundwater levels may partly increase significantly. Therefore, the maximum groundwater level is at about 1.3 m below ground surface."

"In the construction area, maximum frost penetration depths of 0.8 m are to be expected."

"Infiltration of rainwater is possible from the lower edge of the future topsoil (e.g., infiltration shaft or infiltration basin). The bottom of the infiltration system should be above the maximum water level. It would be conceivable to store the occurring rainwater in a cistern to enable further use and only allow the excess water quantities to infiltrate."

"Infiltration of stormwater is possible from the bottom edge of the future topsoil (e.g., infiltration shaft or infiltration basin). The bottom of the infiltration system should be above the maximum water level. It would be conceivable to store the collected stormwater in a cistern in order to reuse it and only allow the excess water quantities to infiltrate."

There you have the answer. Just a few drainage pipes do exactly: nothing.

Otherwise: sewer system?

Do you see any problems with the project?

Hello vaderle

you should first obtain and observe the applicable regulations. Infiltration does not mean letting it run uncontrolled and waiting until it is gone. Infiltration must also be able to handle heavy rain without flooding the surroundings for hours.

Steven

Possibly additionally a cistern. This way you will have water available for the garden later on.

Hello vaderle

you should first obtain and comply with the valid regulations. Infiltration does not mean letting it run uncontrolled and waiting until it is gone. Infiltration must also allow heavy rain to infiltrate without flooding the surroundings for hours.

Steven

Hello Steve,

securing regarding legal regulations is understood. The situation with heavy rain arises anyway even if I wouldn't carry out any piping work, right? And according to the soil report, the soil is very permeable. So water should generally infiltrate well.

@Rick: I did not want a cistern since a water pump is already planned anyway and the cistern would then be unnecessary because there is enough groundwater and it is not very deep.