Sewer networks serve the purpose of quickly and completely discharging storm water as well as domestic and industrial waste water, avoiding sewage exposure in the community. A properly working sewer system is essential for impeccable hygiene, a high standard of living, water pollution abatement, and healthy economic development. The sewer networks in the Ruhr catchment area are usually owned, maintained, and operated by the local communities.
Waste water is discharged to the sewage treatment plantin either a combined or a separate sewage system. In the combined system, waste water and storm water are discharged together in a single sewer with storm water treatment plants protecting the sewage treatment plant from peak run-offs. In the separate system, waste water is discharged in two separate sewers. The waste water is led to the sewage treatment plant in its own sewer while the non-contaminated storm water is discharged directly into a body of water from a parallel storm water sewer.