Length of the German sewer network

595.000 km is the total length of the German sewer network.

By the way, in Germany there are mainly three different types of sewer networks: Mixed water (~250.000 km) , rainwater (~125.000 km) and sewage water (~220.000 km).

Source: https://de.dwa.de/files/_media/content/03_THEMEN/Entwaesserungssysteme/Kanalumfrage/Zustand-der-Kanalisation-2020.pdf