When does the Berlin bathing season end?

The official monitoring season runs from 15 May to 15 September every year. Within it, the Landesamt fuer Gesundheit und Soziales samples all 39 official bathing sites every 14 days under the EU bathing water directive and the Berlin bathing water regulation. From 16 September there are no samples and no published assessment until the following May. Staffed beaches set their own dates on top of that: Strandbad Wannsee closed its swimming season on 13 September 2026 and stays open for sunbathing and the sauna until 4 October.

Are Berlin lakes safe to swim in after the season ends?

Nothing about the water changes on a date, and in most respects autumn helps. Swimmer’s itch needs warm water, and the blue-green algae that build from July fade as temperatures drop. What you lose is the backstop: if something goes wrong with the water at your spot after 15 September, no fortnightly sample will catch it and no warning will be published. Read your site’s own page before the season closes, note its flags, and judge the shore with your eyes when you get there.

What does the official water quality grade actually cover?

Two things: Escherichia coli and intestinal enterococci, both indicators of faecal contamination. The grade is not this week’s reading either. It is a classification calculated after each season closes from 40 results per site across the previous four seasons, in four categories from excellent to poor. Every one of Berlin’s 39 official sites currently holds the top category, checked on 12 September 2026, which means the grade tells you Berlin’s bathing water is not contaminated with sewage and nothing at all about which lake to pick.

Which Berlin bathing sites have blue-green algae?

30 of the 39 official sites are flagged for possible mass growth of blue-green algae, including the Mueggelsee, Wannsee, Ploetzensee, Weissensee and most of the Havel and Dahme sites. Almost all Berlin bathing spots lie on shallow, nutrient-rich river lakes, and blooms develop from July onwards. The flag is deliberately kept out of the water quality classification and assessed separately, so a site can hold the top grade and carry a bloom at the same time. Avoid visible green or blue-green streaks, flakes and mats, keep children away from them, shower afterwards and rinse your swimwear.

Which Berlin bathing sites have a lifeguard?

29 of the 39 list water rescue, and in every case only as present at times rather than all day: the DLRG at 15 sites, the ASB at 6, the DRK at 1 and the rest unnamed. 10 sites list no rescue cover at all, including Schlachtensee, Krumme Lanke, Strandbad Halensee, Flughafensee and Strandbad Tegel. Separately, 24 of the 39 bathing areas are not screened from boat traffic, and eight sites have neither a screened area nor any listed rescue.

Can you take a dog to a Berlin bathing site?

Almost never. 38 of the 39 official bathing sites forbid dogs outright. The single exception is Strandbad Weissensee, which allows a dog on a lead on the terrace only. There is also a health reason to keep dogs out of some lakes: after dogs died at the Tegeler See in 2017, a class of water-plant-associated cyanobacteria producing anatoxin was identified that occurs in clear, clean-looking water and was not covered by the old monitoring strategy.

Which Berlin bathing sites have step-free access to the water?

Five of the 39: Strandbad Wannsee, Strandbad Orankesee, Strandbad Gruenau, Strandbad Luebars and Strandbad Heiligensee. Every other official site is listed as not barrier-free, and 21 of them note that both the water access and the toilet are not barrier-free. On toilets generally, 16 sites have a permanent one, 13 only a portable one and 10 have none at all.

Which Berlin districts have official bathing sites?

Eight of the twelve, and the distribution is lopsided. Treptow-Koepenick has 11 and Reinickendorf 9, so half of all the official bathing sites in Berlin sit in two districts. Steglitz-Zehlendorf has 7, Spandau 5, Charlottenburg-Wilmersdorf 4, and Lichtenberg, Mitte and Pankow have one each. Friedrichshain-Kreuzberg, Tempelhof-Schoeneberg, Neukoelln and Marzahn-Hellersdorf have none, which is why swimming in Berlin usually starts with an S-Bahn ride.

Berlin Bathing Season: What Stops on 15 September and What the Grade Leaves Out

Q: What is swimmer’s itch and which Berlin lakes have it?

It is bathing dermatitis, caused by cercariae: roughly one millimetre long flatworm larvae that live in ducks and other waterfowl, reach the water in bird droppings, multiply in shoreline snails and then swarm in warm water looking for a bird. A swimmer is the wrong host, so the larvae burrow into the skin and die there, leaving itchy wheals two to eight millimetres across that can last up to three weeks. It is harmless beyond the itch and only treated symptomatically. 14 of the 39 official sites carry the note, among them Wannsee, Schlachtensee, Krumme Lanke, Strandbad Mueggelsee and Strandbad Ploetzensee. The risk rises after the water first passes 20 degrees and can return in a second late-summer window.

Yusuf Ucuz

4 minutes ago

7 min read

The water in Berlin is still warm this weekend, and two clocks are about to run out on it. Strandbad Wannsee swims its last official day of the year on Sunday 13 September, then stays open until 4 October for sunbathing and the sauna only. Two days after that, on Tuesday 15 September, the state stops testing the water at every one of Berlin's official bathing sites.

I have swum in the Havel in October more than once, so I am not about to tell anyone to stop. The end of the Berlin bathing season does not change the lake. It changes the information.

And that is worth knowing for a second reason. If you have been reading the official green dot for your lake all summer and taking it as a verdict on the water, the dot has been telling you much less than you think.

The beach and buoyed swimming area at Strandbad Orankesee in Lichtenberg under a wide blue sky in mid-September

Strandbad Orankesee in Lichtenberg on 14 September, the day after the swimming season closes at most staffed beaches. The buoys stay in the water longer than the lifeguards do.

What the Berlin bathing season actually measures

Berlin monitors 39 official bathing sites through the season, and the season has fixed ends: 15 May to 15 September, with samples taken every 14 days. That is nine samples per site per year, under the EU bathing water directive and the Berlin bathing water regulation. Between samples, nobody is in the water with a bottle.

The grade you see is not a reading from this week either. It is a classification worked out after each season closes, from 40 results per site across the previous four seasons, and it covers exactly two things: Escherichia coli and intestinal enterococci. Two gut bacteria, four years, four possible grades: excellent, good, sufficient, poor.

So how do Berlin's 39 sites compare? They do not. Every single one currently carries the top grade, checked on 12 September 2026. Read as a ranking, the official classification is a flat line. It is a statement that Berlin's bathing water is not contaminated with sewage, which is genuinely good news and completely useless for choosing between Wannsee and Krumme Lanke.

Swimmers and sunbathers packed onto the small sandy bathing area at Krumme Lanke in Zehlendorf on a summer afternoon

The bathing area at Krumme Lanke in Zehlendorf. It holds the same top water grade as every other official site in the city, and no water rescue is listed here at all.

The hazard the grade leaves out on purpose

Here is the part that surprised me when I read the regulation. Blue-green algae are explicitly excluded from the classification. The Berlin rules say a mass development of cyanobacteria is not counted in the grade and has to be assessed separately. A lake can hold the top mark and a bloom on the same afternoon, and the two facts never meet.

Which matters, because algae are not rare here. 30 of the 39 sites are flagged for possible mass growth of blue-green algae. Almost all of Berlin's bathing spots sit on the backed-up river lakes of the Dahme, Spree and Havel or on shallow, nutrient-rich local lakes, and from July onward blooms build in most of them.

The sensible response is not to stay out of the water. It is to trust your eyes, which are better at this than a four-year average:

Skip any patch with visible green or blue-green streaks, flakes or mats, and keep children out of it. They swallow water while they play.
Fine cells spread through the water turn it green and very cloudy. Bunched-up algae can drift to the shore as foam while the water stays clear.
Shower afterwards wherever you can, and rinse your swimming things.
Wind and current move a bloom across a lake within hours, so the shore you checked in the morning is not the shore you swim from in the afternoon.

The dog story is the one I would want a dog owner to know. After dogs died at the Tegeler See in 2017, a class of cyanobacteria was identified that lives with water plants, produces anatoxin, and turns up in clear, clean-looking water that the old monitoring strategy was not designed to find. Clear water is not a clean bill of health.

Autumn trees along the far bank of the Müggelsee with a large raft of waterbirds gathered on the open water

The Müggelsee in Treptow-Köpenick, one of the 30 sites flagged for possible algae. The birds on the water are also the first link in the chain that causes swimmer's itch.

The itch that comes from the ducks

14 of the 39 sites carry a cercariae note, and it is the flag I see explained least often at the shore.

Cercariae are roughly one millimetre long, the larvae of flatworms that normally live in ducks and other waterfowl. The eggs reach the water in bird droppings, infect snails in the plant-rich shallows, multiply inside them, and then swarm out in warm water hunting for a bird. A swimmer is the wrong host. The larvae burrow into human skin and die there within a short time.

What you get is bathing dermatitis: itchy wheals two to eight millimetres across that can last up to three weeks. Unpleasant, sometimes miserable to sleep through, and otherwise harmless. There is no treatment beyond anti-inflammatory creams for the itch itself.

Two details make this practical. First, the swarm needs warmth: it happens mainly in early and high summer, after the water has first passed 20 degrees, and a long warm spell can open a second window in late summer. Second, the larvae survive only two or three days in open water and cannot be seen or predicted, so a lake with the note is not dangerous today and safe tomorrow in any pattern you can plan around. Berlin's own conclusion is blunt: the only real control is keeping waterfowl away from bathing areas. Feeding the ducks at a swimming spot is feeding the itch.

Rowing boats moored along a wooden jetty at the Schlachtensee boat hire in Zehlendorf

Schlachtensee in Zehlendorf carries the cercariae note, lists no water rescue, and has only a portable toilet. None of that shows up in its water grade.

Who is actually watching the water

This is where the 39 sites finally separate, and it has nothing to do with water quality.

Water rescue is listed at 29 of the 39 sites, and in every single case as present at times, never all day. The DLRG covers 15 of them, the ASB 6, the DRK 1, with the rest unnamed. That leaves 10 sites with no rescue cover listed at all, including Schlachtensee, Krumme Lanke and Strandbad Halensee.

Then there is the traffic. 24 of the 39 bathing areas are not screened from boat traffic, which on the Havel and the Dahme means you are swimming where boats go. Eight sites have neither a screened bathing area nor any listed rescue. Worth a thought if you like a long swim out from the shore at dusk.

The everyday facilities split just as hard:

Toilets: 16 sites have a permanent one, 13 only a portable one, and 10 have none.
Step-free access: exactly 5 of 39 are listed as barrier-free with barrier-free access to the water, and they are Strandbad Wannsee, Strandbad Orankesee, Strandbad Grünau, Strandbad Lübars and Strandbad Heiligensee.
Dogs: 38 of the 39 forbid them outright. The single exception is Strandbad Weißensee, and only on a lead on the terrace. If you were planning a lake day with the dog, the Berlin dog parks and off-leash areas are the honest answer instead.

Geography is lopsided too. Only 8 of Berlin's 12 districts have an official bathing site, and half of all of them sit in two: Treptow-Köpenick has 11 and Reinickendorf 9. Friedrichshain-Kreuzberg, Tempelhof-Schöneberg, Neukölln and Marzahn-Hellersdorf have none at all, which is why so many Berliners' idea of a swim starts with a 40-minute S-Bahn ride.

One small piece of good news for five specific shores: Kleine Badewiese, Grunewaldturm, Breitehorn, Radfahrerwiese and Lieper Bucht on the Unterhavel sit behind a forecasting model as well as the sampling, because short pollution spells reach them after heavy rain.

The listed brick and cream entrance building of Strandbad Wannsee with an empty cobbled forecourt out of season

The gate at Strandbad Wannsee out of season. Wannsee is one of only five official bathing sites in Berlin with step-free access down to the water, and the listed path from this building down to the beach has been rebuilt and is open again.

What actually changes on 16 September

Nothing about the lake. The sampling stops, and the published assessment stops with it. The flags on each site describe the place and not the week, so they are all still true on 20 October: the algae-prone lakes are still algae-prone, the cercariae sites still have the same snails and the same ducks.

If anything, the arithmetic moves in your favour as the water cools. The itch needs warmth, and blooms that built through July and August fade as the temperature drops. What you lose is the backstop: from the 16th, if something is wrong with the water at your spot, no fortnightly sample is going to tell you and no warning is going to be published.

My advice: read your own site's official page once, this week, and note its three or four flags. That takes two minutes, it does not expire on 15 September, and it is the only version of this information that is actually about your lake. The list of all 39 bathing sites is where warnings and bans appear during the season, and badegewaesser.berlin.de carries the map.

Then, from Tuesday, swim the way people swam here before anyone published a grade. Look at the water. Look at the shore. If it is green and smells, walk fifty metres. If there is no one on the beach and no rescue post, do not swim out further than you would swim back.

The Orankesee in the evening with still water reflecting the trees on the far bank

The same Orankesee in the evening. Berlin's lakes are at their best in the weeks when the official season has closed and the crowds have gone with it.

If you would rather have a lane and a lifeguard

Not everyone wants an unmonitored lake in October, which is fair. Two practical moves:

The indoor pools take over from here, and they are open all winter. My Berlin swimming pools guide covers how the 90-minute ticket works and which halls are worth the trip.
If it is the lake and the day out you want rather than the swim, the Berlin lakes guide has the shores that are still good company in a coat, and mushroom picking around Berlin is the autumn version of the same S-Bahn trip.

And if your Saturday in the city ends up on foot instead of in the water, my free walking tour through Berlin's old centre covers 11 stops and 16 places in about 2 hours, ending at Hackescher Markt.

Image credits

Source and licence details for the 5 photographs used in this article.

The beach and buoyed swimming area at Strandbad Orankesee in Berlin-Lichtenberg: Lukas Beck, CC BY 4.0, via Wikimedia Commons.

The bathing area at Krumme Lanke in Berlin-Zehlendorf on a summer afternoon: Fridolin freudenfett, CC BY-SA 4.0, via Wikimedia Commons.

Waterbirds on the Mueggelsee with the autumn shore behind them: Pascal Volk, CC BY-SA 2.0, via Wikimedia Commons.

Rowing boats at the Schlachtensee boat hire in Berlin-Zehlendorf: Fridolin freudenfett, CC BY-SA 4.0, via Wikimedia Commons.

The Orankesee in the evening light: abbilder, CC BY 2.0, via Wikimedia Commons.