In the streets of Hamburg, Germany, a new form of urban deterrent is turning public urination into an instant lesson in cause and effect. Known as “anti-pee paint,” this specialized nano-coating creates a superhydrophobic surface, repelling liquids so completely that anything touching it slides off with remarkable force. The result? Anyone attempting to relieve themselves on a treated wall experiences an immediate and unforgettable splash-back. The technology borrows from nature, mimicking the microscopic structure of a lotus leaf. Tiny ridges and air pockets prevent any liquid from adhering, meaning walls remain clean while offenders get an eye-opening consequence — all without the need for confrontation, fines, or patrols. It’s an ingenious blend of physics and human psychology: the paint doesn’t punish with authority, it punishes with instant feedback. First popularized in Hamburg’s St. Pauli district in 2015, this approach has since been trialed in other cities like London and San Francisco. While the coating is costly, city authorities note significant savings on cleaning and maintenance, and a marked decrease in repeat offenses. Beyond hygiene, it’s a striking example of how urban design and material science can work together to shape behavior. For engineers, urban planners, and city residents, anti-pee paint is both a marvel of nano-engineering and a lesson in poetic justice. The streets stay cleaner, the message is immediate, and the offender leaves with a story they won’t soon forget.
When they piss on the piss-splashing paint, it splashes them with piss, so they stop. I believe the point is that it sprays back at all angles.
I’m not claiming it’s a magic bullet, but I am claiming that if you think this is about homeless people you are not thinking about drunk people and tourists, who are the genuine target.
I’m not claiming it’s about homeless people, it just seems like a waste of money to me, and it fails to address the issue of people not having a place to piss.
The paint is merely hydrophobic, all you have to do is piss at an angle and you’ll be fine. It’s not a piss retroreflector. It’s akin to pissing on a waxed surface.
Just a logistical question about how this works , does the pee reflect equally in a hemisphere normal to the surface, or does it reflect off the wall like a normal reflection.
If it is option 1, how does that work physically? Is the surface multi-faceted? Even with a hydrophobic surface I would still expect a normal reflection.
I don’t really see what’s so bad about peeing outdoors so long as it regularly rains, and you’re not peeing in a way that will affect others.
I don’t know the details, but as soon as you break up the stream it will not reflect cleanly.
Peeing in a city is always going to affect others - there will be people nearby who don’t want to see and hear it, and unless it is raining at that moment, it will leave a mess that affects people. I believe even peeing in the countryside can cause some negative effects due to nitrogen run off.
I suppose we will have to agree to disagree. I don’t think it always affects others if you do it in private in a place where people don’t walk, and rain can hit it.
Everything has an effect, especially if lots of people do it. You do not want to pee within 100 ft of a stream if you can help it. It is better to let the pee break up in the soil. The real problem for ecology is the salts in urine. That’s why if a dog pees in the same spot every time, plants die.