Too little wastewater in the sewer, long periods without rain or technical causes can lead to deposits in the sewer network that obstruct the flow or cause odors.

For this reason, the city of Bonn carries out regular cleaning of public sewer systems as part of its sewer maintenance program.

Sewer cleaning is carried out according to a flushing schedule. The legal basis for this is the Sewer Self-Monitoring Ordinance (SüwV Kan).

Unscheduled cleaning is also carried out spontaneously in the event of blockages or unpleasant odors.

The sewers are cleaned with cleaning vehicles, so-called "combined flushing and suction vehicles".

This is currently done in the city of Bonn with a total of three vehicles, two of which automatically filter the wastewater from the sewers and then use it for sewer cleaning. This allows sewer cleaning to be carried out ecologically and economically at the same time.

For traffic reasons, a few sewers in the city can only be cleaned at night. This "night cleaning" is communicated to residents in advance by means of letters to residents and publications in the daily press.