Harmful substances, such as algae and E.coli, are polluting the lakes in Berlin, making it unsafe and unadvisable for swimming.
In the warmer months of the year, Berlin's lakes can be a popular destination for swimming and recreation. However, a potential hazard lurks beneath the surface - toxic algae blooms.
These blooms can negatively impact the quality of water in Berlin's lakes, making swimming potentially dangerous. As a result, several areas along the Havel, such as Strandbad Wannsee, Grunewaldturm, Kleine Badewiese, Breitehorn, Lieper Bucht, Radfahrerwiese, Große Steinlanke, Alter Hof, have been advised against for swimming due to the presence of blue algae.
Swimmers are encouraged to be vigilant and look out for signs of toxic algae. As of mid-August 2025, there is no specific swimming ban in Berlin's lakes reported, but the situation can change rapidly depending on water quality testing.
In the city's main river, the Spree, swimming remains officially banned, with recent protests to lift the ban.
Regarding algae and E.coli bacteria specifically, no direct advisories or closures have been reported for Berlin's lakes. However, in other regions, such as New Hampshire lakes in the USA, fecal bacteria advisories have been issued at certain city beaches. But these reports do not pertain to Berlin.
Lageso has issued a warning against swimming at Teufelsee in Grunewald due to the presence of E.coli bacteria. The blue algae in the Unterhavel is noticeable through streaks and carpeting on the water's surface.
Toxic algae can cause health problems for swimmers, including skin irritations and allergic reactions in children and people with sensitive skin. It can also pose a risk to the health of birds and other wildlife.
A large body of water can be impacted by E.coli bacteria through faeces sent in flows of wastewater or runoff from agricultural areas. Swimmers and even birds can contribute to the problem.
If you are planning to swim in Berlin's lakes, it would be prudent to check with local environmental or health authorities for real-time updates before swimming. On Tuesday, August 20, swimming is not recommended in Berlin lakes due to the presence of toxic algae.
In summary, while Berlin's lakes remain a popular destination for swimming and training activities, it is crucial to exercise caution during the summer months. Swimmers should be aware of the potential risks associated with toxic algae blooms and E.coli bacteria, and always check for any advisories or warnings from local authorities.
Science has shown that toxic algae blooms can negatively impact the health-and-wellness of swimmers in Berlin's lakes, causing skin irritations and allergic reactions. Furthermore, the presence of these blooms can also have a negative impact on the environmental-science of Berlin's lakes, affecting not only the quality of water but also the health of birds and other wildlife.
