July 1, 2025, 2:08 pm | Read time: 3 minutes
On warm days, thousands flock to Germany’s lakes. However, not all swimming spots have public restrooms. So, what should you do when nature calls? Just pee in the lake? TRAVELBOOK investigated whether that’s a problem.
The most noticeable are those who are usually afraid of water. Those who hardly dare to venture a meter from the shore. But when nature calls, they become brave. They go just deep enough into the water to cover their swim trunks, look around furtively—and eventually reveal themselves with a facial expression that gives them away: They smile with relief. Others swim as far out as possible or find a secluded spot in the next bay of the swimming lake to relieve themselves.
Almost everyone has secretly peed in a swimming lake at some point, even if no one openly admits it. It’s just too tempting to relieve oneself in the vastness of the lake when there’s no restroom nearby. But is it actually bad to pee in a swimming lake? Does it harm the water or other swimmers?
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The Larger the Swimming Lake, the Less Harmful the Peeing
“Anything that contributes to adding nutrients to the lake should be avoided,” says Matthias Oloew, spokesperson for the Berlin Pools, when asked by TRAVELBOOK. Because urea, the main waste product of our urine, nourishes algae. “While they are harmless, some visitors don’t find them particularly aesthetic,” says Oloew. Generally speaking, the larger the lake, the less harmful the urine entry into the water. “The Wannsee, for example, is large, so if a few hundred people pee in it, it’s not a big deal,” explains the water expert.
Especially in years with high swimming activity and greater dryness, as currently caused by the heatwave, smaller lakes are comparatively at risk. Here, the contribution to algae growth from urine is not insignificant, adds Michael Häckl from the Hessian State Office for Environment and Geology. “The ratio of total input to lake size is crucial,” says Häckl. Only fishermen and anglers have occasional interest in higher nutrient levels. The reason: It allows for faster production of higher fish mass. “In terms of nature conservation and also for swimmers, this is not beneficial in any case,” says the water ecology expert.
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Significant Ecological Consequences Possible
The Great Wannsee is actually a bay of the Havel and is flowed through by its water. “Here, the urine entry is carried further and dissipates,” says Matthias Rehfeld-Klein from the Berlin Senate Department for Mobility, Traffic, Climate Protection, and Environment. Especially in smaller lakes that are not flowed through, the urine entry by swimmers is quite relevant. “The lake has no outflow, nutrients are gradually enriched, leading to eutrophication with significant ecological consequences.” In addition to phosphorus in urine, germs also enter the water. These can cause contamination and, depending on water exchange and swimming intensity, can also be hygienically relevant.
But what about the sea? Can I pee in it without any problems? You can find the answer here.
No matter how a lake is structured, you should still suppress the urge to pee. Matthias Oloew from the Berlin Pools has a clear statement on the topic: “You should generally not pee in the lake. It’s simply not appropriate.”