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Sewage Treatment Plants

Over 95% of the German population is connected to the public sewage system. Wastewater is treated in more than 10000 sewage treatment plants.

Generally speaking, the municipalities are responsible for sewage treatment plants. There are also privately operated sewage treatment plants. Around 10.5 billion m³ of wastewater are treated per year in the public sewage treatment plants.
At these plants there are three treatment stages:

  • A mechanical stage (0.1% wastewater treated),
  • A biological stage without the targeted removal of nutrients, such as nitrogen and phosphate (5%),
  • A further biological stage with the targeted removal of nutrients (95%).
The positive consequence is an increase in the oxygen content of these waters. Thus the foundations of life for fish fauna and other water organisms have been improved.
A total of more than 90 billion Euro has been invested in the sewers and sewage treatment plants in Germany since 1975.