The Stormwater Experts



In respect to “INTERREG III B” program, “NORIS” (No Rainwater in Sewers) was a project funded by the European Regional Development Fund as part of a community initiative to promote transnational co-operation on spatial planning in the North Sea Region.

Five partner countries were involved: Belgium, Germany, the Netherlands, Sweden and the UK each conducted pilot studies that addressed different problems of excess rainwater entering the sewer system.

The two main aims of the "NORIS" project were:

  • to improve water quality in receiving waters, and
  • to reduce additional negative effects of rainwater (or non-foul flows) by limiting its discharge in sewer systems.

The German project partner was the city of “Hannover” that worked closely with “Ingenieurgesellschaft Prof.Dr.Sieker mbH” to generate an Urban Water Management strategy for the main purpose of optimizing the water quality in the city.

The city of "Hannover" focused, since the 70’s, on the gradual separation between Storm and sewage system .However it turned out to have a negative effect on the water quality within the city.

The solution consisted of storages with throttle discharge, regulating and controlling the flow of storm water into the system.

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Project information

Links 1
Dr.-Ing. Harald Sommer
+49 3342 3595-16
Dipl.-Ing. Mike Post
European Regional Development Fund Interreg IIIB
Stadtentwässerung Hannover