Infiltration is allowing water to sink into the soil. In built-up areas, the large percentage of paved surfaces hinders natural infiltration. Sidewalks, streets, buildings and parking lots do not allow rainwater to pass through. Almost everywhere the rainwater is therefore discharged via the sewer to the treatment plant or to nearby surface water. But when it rains hard, the sewers cannot handle the amount of rainwater and the street is flooded. It is also possible that the treatment plant cannot cope with the volumes of water and discharges the rainwater together with the sewage into the surface water, which subsequently becomes polluted.
Header image: EDE - BOOMSPIEGEL
Icon image: EDE - BOOMSPIEGEL