Stockholm reports massive sewage discharge into Lake Mälaren

66 million liters of sewage were dumped into Lake Mälaren last year. The cause was rain that flooded the old sewer systems.

Last year, 66 million liters of untreated sewage were discharged into Lake Mälaren, according to Stockholm Water and Waste. The cause of the discharge is an old sewer system that easily floods when it rains.

– There is a big difference between a dry year and a wet year, Anders Lundin, environmental and health inspector for the city of Stockholm, told TV4 News.

In modern sewage systems, wastewater from households and rainwater are separated. In the past, a large pipe was built to the treatment plant, which means that the pipes cannot cope if too much water comes in. This is called overflow.

This can lead to eutrophication of the lake and the spread of diseases among people, including stomach flu and diarrhea.

– A single rainfall creates a temporary dose of fecal matter in the water, which disappears within a week or two. By then other microorganisms will have eaten the bacteria, Lundin told Schibsted newspaper SvD.

Swimming is currently advised against at seven beaches in Stockholm.