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Most of Berlin's swimming spots are suitable for swimming - however, according to the State Office for Health and Social Affairs (Lageso), warnings are in effect for the Breitehorn and Radfahrerwiese swimming spots on the Havel River.
According to the water quality assessment, both swimming areas are experiencing a massive bloom of blue-green algae and very poor visibility, which could make water rescue operations more difficult.
In accordance with a recommendation from the Federal Environment Agency, additional tests for blue-green algae toxins are being conducted. According to Lageso, all 39 swimming areas in the capital are tested regularly during the swimming season. These tests are based on microbiological measurements, particularly of bacteria such as Escherichia coli and enterococci, which provide indications of possible contamination.
After heavy rainfall or during periods of high temperatures, water quality may change temporarily, and blue-green algae may proliferate. According to Lageso, algae growth increases as water temperatures rise and light levels are high. All other Berlin swimming spots are marked in green on the overview map: they are suitable for swimming.