Sometimes, public urination can be more than just a nuisance. In many cities, it’s a persistent problem that damages infrastructure, creates unsanitary conditions, and frustrates residents and businesses alike. Hamburg, Germany, like many urban centers, has faced its share of challenges with “wildpinkeln,” or wild peeing, as the locals call it.

Well, some locals have decided to tackle the issue creatively and innovatively—with hydrophobic paint.

Playing the Uno card

Hydrophobic coatings aren’t new, but they’re not typically used against urination. The coating is essentially a thin layer that repels water by forming an almost imperceptibly thin layer that repels water on top of a surface.

The paint contains microscopic particles (often silicon dioxide or similar compounds) that form a super-slick, nonporous coating when applied. This coating dramatically reduces the surface tension between the wall and any liquid, causing the liquid to bead up and roll off instead of spreading or soaking in. The principle mimics natural water-repellent surfaces, like lotus leaves, which evolved to resist moisture.

When someone goes to pee on the coated surface, it beads up and bounces off instead of soaking in. The result? Anyone relieving themselves directly against a wall painted with this material ends up getting splashed by their own urine.

The approach was first deployed in Hamburg in 2015, in the St. Pauli neighborhood — specifically, on the Reeperbahn street, known for its vibrant nightlife. Many of the neighborhood’s visitors end up relieving themselves on the wall, treating some alleyways and building exteriors as open restrooms.

The most “attacked” areas were treated with the coating and added phrases like“Don’t Pee Here! We Pee Back!”. Reportedly, public urination has gone down since then.

“This paint job sends a direct message back to perpetrators that their wild urinating on this wall is not welcome,” Julia Staron, who organised the event, told Reuters.

The method is catching on

Hamburg isn’t alone in using this approach. Just months after the St. Pauli implementation, the city of San Francisco also gave it a go. Public urination has been a problem in San Francisco for decades, but it’s not clear whether hydrophobic paint actually helped in this case.

More recently, London also made its own hydrophobic paint anti-pee campaign.

“Residents and businesses are fed up. It’s finally pee-back time and we’re taking action to stop people using alleyways or doorways as a toilet. The ingenious paint is one of a number of steps we are taking to discourage people from relieving themselves in public or on private property,” said Councilor Aicha Less.

The approach seems to becoming more popular in England. In 2024, the town of Cheltenham, home to one of the biggest horseracing events in the world, declared a ‘war on wee’ after people kept peeing everywhere during the festival.

But is this really effective?

It’s hard to find clear numbers that assess just how much urination this type of painting deters. Initially, there seems to be a decrease, but it’s unclear whether this decrease is sustained or not.

Critics argue that the paint targets the symptoms rather than the root cause of public urination. Simply building more toilets could be a more permanent solution. Another criticism is that people can just pee “diagonally” and avoid all the splashing.

It’s also pretty expensive.

It costs around $500 to paint a six-square meter area (65 sq feet), and the paint can lose its hydrophobic quality after a few years. Yet supporters say it’s well worth the investment.

“If you compare the work involved for daily cleaning of the mess and the awful smell, as well as all the collateral damage involved, it has definitely been well worth it,” she said.

Ultimately, Hamburg’s approach seems to be slowly growing in popularity — a reminder that even the most persistent problems can be addressed with fresh thinking. It’s hard to dislike the blend of humor, science, and practicality. After all, the city has turned an everyday annoyance into an opportunity for innovation. It remains to be seen whether the method will catch on in more cities as well.