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.
If enough public toilets were actually provided, this would not be a problem that needs solving.
Right I'm sure the people who piss in our gateway, mysteriously every Friday and Saturday while bellowing at each other, are homeless rather than smashed out of their tiny troglodyte minds.
Hamburg has a vast number of tourists, which makes it even worse, because tourists don't have to live in the city they're pissing all over, nor see again the person they flashed because the fumbled pulling up their pants.
If there was a toilet right there, do you think they would still choose the wall?
If they would still choose the wall, do you think the paint is going to deter them?
How will people even know that the paint is piss-splashing paint?
Will people not immediately change their piss angle as soon as they get splash back?
They have walked out of a club with a toilet five minutes ago. How frequently do you want there to be toilets?
The idea is that by putting the risk in people's minds it'll be a deterrent, or else by giving people a natural consequence (and also protecting the wall from being stained with piss) it'll deter repeat offenders.
Keep going down the list of questions, I’ve already accounted for other reasons why this is a dumb idea
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.
Well, they claim that statistically the problem became less severe, so maybe it does work
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.
Oh, you mean the gross, overcrowded toilet that is typical of clubs? Weird that they didn't want to use that. I wonder why that could be?
/sarcasm
No, just a regular toilet in a public establishment. I don't know anyone who's thinking "this toilet is gross, so I'll piss in the fucking street". I guarantee you noone is wiping down the street with anti bacterial spray.
Toilets can get busy, yet queuing for one is very normal. Have you noticed that no-one sees the queue and goes on the corner?
That's because this is caused by drunk people failing to plan ahead and then when caught short not having any inhibitions.
Guys really don't care, less so the more they drink. Wall is more convenient than a toilet around the block whether it's sparkling or not.
You can't build public toilets every 50m and make sure it stays clean. Anything further than 50m and a drunk person will just piss to the next wall/bush/corner as they can't be bothered with finding a proper restroom in many cases. Its not as simple as you make it out to be.
Great, now keep going down the questions I posed.
The point I’m making is that this paint won’t do a thing except cost money.
Yeah, not everything is about the homeless. Are there actually many homeless in Munich, compared to rude tourists?