Handling of drainage-system water from private sites - IKT – Institute for Underground Infrastructure

Illegal drainage system connection to a public sewer

The discharge of site and drainage-system water into the public sewer network is expressly prohibited in the majority of waste-water regulations in North Rhine-Westphalia. In many municipalities there are, nonetheless, numerous such drainage connections. How, then, should this issue be handled at local level? A guideline drafted by the IKT and the NRW Municipal Agency (KommunalAgenturNRW) provides orientation.

There can be a range of reasons for connected water-drainage systems. It may be, for example, that a drainage system was actually intended only for the construction phase, but then remained connected “just to be on the safe side”. Or the drainage system might have been installed despite the ban on permanent drainage. Leaking building sewer laterals and site sewer laterals can also act as drainage systems. Why do the municipalities prohibit the discharge of ground and drainage-system water, and why is drainage-system water discharged, despite the ban?