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.
The Cornucopia is just asking for trouble, given how poorly most guys aim.
Splash back, so refreshing when wearing shorts on a hot day.
You bet.
Piss on it; we're trillions in debt, pissing away our taxpayers' $$$$$$.
Not a new concept. I thought this was one reason many older urinals extended to the floor. Aim it to hit the urinal wall halfway down and no splashback.
Funding and Disclosures
This research was supported by the University of Waterloo, Weber State University, and the Natural Sciences and Engineering Research Council of Canada (NSERC) through Undergraduate Student Research Awards (USRA). The authors declared no competing interests that might influence their work or its interpretation. The study was conducted as part of academic research with the stated goal of improving sustainability, hygiene, and accessibility in public facilities.
Yeah, and it doesn't look too short-people friendly either.
The Nautilus...made for the Brother with the big wang!
And they were usually curved inward so that the splashes, if any, would still be caught ......................
“Waterloo”? They’re trolling us, right?
What a relief!
Tim Walz, the sitzpinkler, wants men in Minnesota to sit while peeing. They’ll hire washroom attendants to enforce the policy.
It’s a real place:
Waterloo, Ontario, Canada..............
https://en.wikipedia.org/wiki/University_of_Waterloo
Wonderful that they are developing new urinals that stop splashback.
The problem that I have is politicians like Marx Carnage urinating on my head, and telling me it is rain. There is one way to stop this, but Laurentianists haven’t figured this out yet. They prefer to dance around and celebrate in the ‘rain’.
that’s why i only pee off of bridges...
3,2,1....
It seems the design should also accommodate women who may wish to use the urinal. Can’t discriminate. Wouldn’t be prudent. :-)
This is why I always pee on the inside edge of the urinal instead of the back because the angle is over 70°. No splashback.
Urinal design could be better because the flat face of the urinal gets urine everywhere.
Just pee outside.
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