Posted on 04/08/2025 7:52:45 AM PDT by Red Badger
In a nutshell
* Researchers discovered that when urine hits a surface at less than 30 degrees, splashback is reduced by 95% compared to perpendicular impact.
* Two new urinal designs—the “Cornucopia” and “Nautilus”—use this critical angle principle to virtually eliminate splashing while improving accessibility.
* Widespread adoption could prevent about one million liters of urine from splashing onto floors daily in the US alone, saving substantial cleaning water and resources.
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WATERLOO, Ontario — For over a century, men’s public restrooms worldwide have featured essentially the same urinal design. Despite their universal presence, these fixtures have a notorious flaw that anyone who’s used them knows all too well—they splash. A team of engineers from the University of Waterloo in Canada and Weber State University in Utah has finally solved this problem using basic physics principles and some clever mathematics.
In a research paper published in PNAS Nexus, the scientists demonstrate how relatively simple changes to urinal geometry can dramatically reduce splashback, improving hygiene and potentially saving millions of liters of cleaning water daily.
The Battle Against Tinkle Sprinkle
The urinal hasn’t changed much since Marcel Duchamp featured one in his provocative 1917 artwork “La Fontaine.” This design stagnation has perpetuated a messy problem: microscopic droplets spraying beyond the fixture onto floors, walls, and sometimes users themselves.
These seemingly minor splashes add up to major issues. With approximately 56 million urinals in non-residential settings across the United States, researchers estimate more than 350,000 liters of urine splashes onto floors daily. Once settled, these droplets become breeding grounds for bacteria and contribute to the characteristic odors of poorly maintained restrooms.
Cleaning this mess requires chemicals, water, and labor. The Toronto subway system spends over $122,000 Canadian dollars annually per bathroom on cleaning costs alone.
Previous solutions have mostly involved add-ons like absorbent mats or aiming targets. Amsterdam’s Schiphol Airport painted small fly images near urinal drains, reportedly cutting spillage by 50-80% and reducing cleaning costs by 8%. But these workarounds never addressed the fundamental physics of the problem.
Three-dimensional renderings of urinals. From left to right: Duchamp’s “La Fontaine,” a contemporary commercial model, Cornucopia, and Nautilus. (Credit: Thurairajah et al)
The Physics Breakthrough: The Critical Angle
Dr. Zhao Pan and colleagues took a fresh approach by examining why splashback occurs in the first place. They found that the key factor was the “impinging angle”—the angle at which the liquid stream hits the urinal surface.
Through mathematical modeling and controlled experiments, the researchers discovered that when a stream hits a surface below a critical angle of approximately 30 degrees, splashback drops dramatically—by about 95% compared to a perpendicular impact.
This principle exists in nature too: when dogs urinate against vertical surfaces, they naturally create a shallow angle that minimizes splash onto their fur—a fortunate side effect of territorial marking behavior.
With this critical angle identified, the team used mathematical equations to design urinal surfaces that would ensure all impacts occurred at or below 30 degrees, regardless of user height or aim. Two distinct designs emerged from this work: the “Cornucopia” and the “Nautilus.”
Revolutionary Results and Real-World Impact
To test their designs, the researchers built prototypes and compared them against a replica of Duchamp’s “La Fontaine” and a modern commercial model. Using a custom apparatus that simulated human urination, they measured splash under various conditions.
The results were striking. While conventional designs created splatter extending up to one meter away, the new designs produced almost no visible splash. Measurements confirmed that under high-splash conditions, the Nautilus design reduced splashback by 85-95% compared to commercial urinals.
Images of splatter generated by each urinal under the medium user height, high flow rate test condition with a total “urinated” volume of 1 L: a) La Fountaine, b) contemporary commercial, c) Cornucopia, and d) Nautilus. The gray visualizes the top plane projection of the foam urinal model used in the splatter tests, whereas the white shows the same projection of the ceramic urinal as it would be installed. The stains from sessile droplets of known volumes are indicated at the same scale as the zoomed sections. (Credit: Pan et al / PNAS Nexus)
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Beyond eliminating splash, the Nautilus design offers practical advantages. Its relatively low profile makes it accessible to users of all heights, including children and wheelchair users—solving another common problem with conventional urinals that require uncomfortable compromises in installation height.
The impact of widespread adoption would be substantial. If these designs replaced existing urinals in U.S. non-residential settings alone, approximately one million liters of urine would stop splashing onto floors daily. Assuming ten times that volume of water is currently used for cleaning, this could save up to ten million liters of water daily—particularly valuable in water-stressed urban areas.
What makes this solution especially elegant is its simplicity. The improved performance comes solely from reshaping the urinal’s geometry, requiring no expensive materials or complex systems. The designs can be manufactured using conventional porcelain and standard techniques, making them immediately practical for widespread adoption.
Like dogs being able to avoid their own spray, now humans can benefit from the same physics principles, through intentional design rather than evolutionary coincidence. From public health to sustainability to accessibility, this reimagining of the humble urinal shows how science can solve everyday problems hiding in plain sight.
Must be where Menard’s got their idea to put their weekly ad over the urinals.
Me not want Hillary Clinton or Adam Schiff’s face anywhere close to my pewee...
This is not new knowledge. My anecdotal experience with properly angled urinals goes back to my fall of 2000 train ride on the Durango and Silverton. The urinals in the depot bathroom appeared to date back to the 19th century, and they had very steeply angled sides and were pretty deep. So I guess our forebears weren’t as dumb as some people think.
Your post reminds of a bar in Mexico I saw as a kid, the foot rest that ran the length of the bar was also a tiled urinal so that you could pee while talking and drinking at the bar.
It’s obviously the “Angle of The Dangle”...
Didn’t think that was possible...I must have heard wrong that Mark Carney squats to pee...
Thanks Badger I read this and now I got to GO!!!
I’ve seen them that have the image of a fly imprinted in the urinal and if you aim for the fly, splash-back is supposed to be eliminated. Its flaw is that depending upon one’s height, the angle differs considerably and the effectiveness is lost.
I always aim for the sides of the urinal to eliminate splash back.
That's so Timmy and his fellow dems can comfortably insert the tampons provided.
So there were these two flies arguing on a urinal....
Don't shine one of these in your bathroom. Trust me on this.
Fenway Park?
That is what all the mens rooms looked like at Fenway until twenty years ago. Until is was finally remodeled.
I was in Sorrento, Italy and they had a trough carved out of solid stone. Literally, carved into the side of the cave/rock face. It probably drained into the Med.
I remember an article on FR many years ago where some state or country was going to force boys in school restrooms to sit while peeing. They claimed urinating while standing up gives boys an unfair advantage in mathematics and physics because they understand arcs, force, and trajectories better than girls.
i was looking for “the water’s cold” and deep too.
Omg, that’s a hoot!
Or a critter, or a midget pervert hiding!
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