Baseboard drainage channel

Good morning,

our outdoor areas will be done soon, and at the points where paving goes up to the house, a base channel (ACO Profiline) will be installed. We are now wondering whether it would be better to drain the base channel into the sewer system or into a soakaway pit. Basically, we would prefer connection to the sewer system. However, the bottom edge of the base channel is below the backwater level. In the event of backwater, wastewater might be pushed into the base channel. The soil is sandy, and the groundwater level is relatively high (about 1-2 m deep).

What do you think?

First thought: A separate backflow protection for the connection of the base gutter.

The soil is sandy, the groundwater is relatively high (about 1-2 m deep).

Where do you drain the rain gutters? I would also drain the base gutters there. Soakaway pit only as an overflow behind a cistern, then you have watering water and the environment is happy. Do you have a basement?

In some municipalities, it is not allowed to discharge rainwater into the sewer at all. Do you already know whether this is even permitted in your area?

How much does the groundwater level fluctuate where you are? We connected the channels to the infiltration shaft for the rainwater. The backwater level is also at ground level for us. However, the groundwater has never reached the GOK here - it was even far from it, so it was clear that it would infiltrate in the infiltration shaft. If you live in a flood zone and there is a chance that rainwater or groundwater will ever reach or even exceed the GOK, it doesn’t really matter. Then either nothing drains anymore or it pushes out. A backflow prevention device only helps temporarily in the latter case because then it pushes back through the street/neighbors’ channels, etc.

Thank you very much for the feedback.

Rain gutters are drained into the sewer system; this is also permitted here. We do not have a basement. In the event of backflow, the wastewater could potentially rise a few centimeters in the rain downpipes, but it should not overflow. However, the bottom of the gutter is at least 9 cm below the RSE (determined as the next higher exit point from the sewer above our connection point). That means without the proposed additional backflow protection, the wastewater would spread in the gutter and reach the building base.

A connection to the sewer system with additional backflow protection would certainly be the premium option but would also involve some extra costs.

The groundwater does not reach the surface. Even before we filled in, the groundwater did not rise to the surface. The neighboring properties lie partly 20 - 40 cm lower. That means before water no longer infiltrates on our property due to the groundwater level, these properties are already flooded. In the case of a hundred-year rain that floods the entire construction area, as Allthewayup wrote, we have a problem anyway.
We also have quite a large roof overhang, so not much water should actually accumulate in the base gutter.

Are there greater concerns with this additional information about draining via a soakaway shaft as described by Allthewayup?