Infiltration (drainage) tunnels with a volume of 300 liters for the retention of rainwater and its controlled drainage into the subsoil. Where there is no sewer, it serves as an overflow from a rainwater storage tank or drains water from the roof directly into the ground. They are also suitable where there is a need to reduce the load on the sewer network that drains rainwater to the wastewater treatment plant.
The required number of sections depends on the amount of rainfall, the area of the drainage area and also on the permeability of the soil.