June 23, 2026, 10:27 am | Read time: 3 minutes
On warm days, thousands flock to Germany’s lakes. But not all swimming spots have public restrooms. So what to 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 barely dare to move a meter away from the shore. But when the bladder presses, they become brave. They go just deep enough into the water to cover their swim trunks, furtively look around in all directions–and finally, they have an expression that clearly gives them away: They smile with relief. Others swim as far out as possible or find a secluded spot in the next cove of the swimming lake to pee there.
Almost everyone has secretly peed in a swimming lake at some point, even if no one admits it openly. 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 the 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 a spokesperson for the Berlin Pools on inquiry from TRAVELBOOK. Because the urea, the main waste product of our urine, would feed algae. “They are harmless, but some visitors don’t find them particularly aesthetic,” the spokesperson says. In general, the larger the lake, the less harmful the entry of urine into the water. “The Wannsee, for example, is large. If a few hundred people pee in it, it’s not that bad,” 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 of algae growth from urine is not insignificant, according to the Hessian State Office for Environment and Geology. The ratio of total input to lake size is crucial. Only fishermen and anglers have occasional interest in higher nutrient levels. The reason: This can produce a higher fish mass more quickly. However, in terms of nature conservation and also for swimmers, this is not beneficial in any case, according to the state office.
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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. Urine is carried away and dissipates there. Especially in smaller lakes that are not flowed through, the entry of urine by swimmers is quite relevant, according to the Berlin Senate Department for Mobility, Transport, Climate Protection, and Environment. In addition to phosphorus in urine, germs also enter the water. These can cause contamination and, depending on water exchange and swimming use intensity, can also be hygienically relevant.
No matter how a lake is structured, you should still suppress the urge to urinate. The expert from the Berlin Pools has a clear statement on the subject: “You should generally not pee in the lake. It’s simply not appropriate.”