What Berlin’s Water Grade Does Not Tell You About Your Lake
All 39 official Berlin bathing sites carry the same top water grade, so the grade cannot help you choose between them. This board shows what does differ: the blue-green algae flag on 30 of them, the swimmer’s itch note on 14, water plants on 17, who is watching the water, boat traffic, toilets, step-free access and the dog rule.
Site list, water-quality classifications and the per-site notes come from the Landesamt für Gesundheit und Soziales Berlin, with the bathing-site geodata published 18 May 2026 and every site page read on 12 September 2026. The EU classification is calculated after each season from 40 results per site across four years and covers Escherichia coli and intestinal enterococci only; blue-green algae are assessed separately under the Berlin bathing-water regulation. A shore changes with the wind and the week, so treat this as each site’s standing profile and not as today’s reading.
Five steps repaint the same board of 39 sites. The first shows the official grade, which is identical everywhere. The next three add the hazards the grade leaves out and the facilities it never covered. The last one greys the board out for 16 September, when the sampling stops. Tap any row to read that shore’s own lines and open its official page.
Why the official grade cannot rank your lakes
Berlin monitors 39 official bathing sites from 15 May to 15 September, sampling every 14 days. The grade you see is not that week’s reading: it is a classification worked out after each season closes, from 40 results per site across the previous four seasons, and it covers two gut bacteria only. Every one of the 39 sites currently holds the top category, which is good news about sewage and no help at all in choosing a shore.
The flag that is excluded on purpose
The Berlin bathing-water regulation keeps mass growth of blue-green algae out of that classification and has it assessed separately, so a site can hold the top grade and carry a bloom on the same afternoon. 30 of the 39 sites are flagged for possible algae, and blooms build from July. Skip any patch with visible green streaks, flakes or mats, keep children out of it, and shower afterwards.
The itch that comes from the waterfowl
14 sites carry a cercariae note. The larvae live in ducks, reach the water in droppings, multiply in shoreline snails and swarm once the water first passes 20 degrees, hunting for a bird. A swimmer is the wrong host, so they burrow into skin and die, leaving itchy wheals for up to three weeks. Harmless beyond the itch, impossible to predict, and worse where people feed the ducks.
Who is watching, and what is actually there
Water rescue is listed at 29 sites and always as present at times rather than all day, leaving 10 with no cover listed at all. 24 of the 39 bathing areas are not screened from boat traffic. 10 have no toilet, only 5 are step-free down to the water, and 38 of the 39 forbid dogs outright.