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Physics Solves One of Man’s Biggest Problems: Urinal Splashing
Study Finds ^ | April 08, 2025 | Staff

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.


TOPICS: Business/Economy; Health/Medicine; Society; Weird Stuff
KEYWORDS: urinetroublenow
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To: woodbutcher1963

Marshfield Fair in Massachusetts. Town fair but it was the size of a county fair. Good sized midway, 4h, local crafts, horse racing with betting, demo derbies and the Chitwood Bros stunt driving shows.

I’m sure it’s all different now in commiechusetts.


61 posted on 04/08/2025 8:42:08 AM PDT by Pollard (Zone 6b)
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To: wildcard_redneck
This is why I always pee on the inside edge of the urinal

Specifically the left edge, as I always want to piss on the left.

62 posted on 04/08/2025 8:42:45 AM PDT by rhinohunter (I don’t know if God is a Republican, but I am metaphysically certain that satan is a democrat)
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To: ansel12
Feminists despise the urinal, yet for many years the feminists researched hard to design one for women...

No matter how hard they try, they will never be able to herd cigarette butts around.

63 posted on 04/08/2025 8:43:35 AM PDT by GingisK
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To: teeman8r
i was looking for “the water’s cold” and deep too.

That's the first thing I thought of...

64 posted on 04/08/2025 8:45:24 AM PDT by Mr.Unique (My boss wants me to sign up for a 401K. No way I'm running that far! )
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To: Rurudyne

As I’ve aged and my stream ain’t what it used to be, there are times when the aiming doesn’t match the exit angle. A few issues with bladder infections along the way have also affected me. Also, there are times when there is a split stream.

I will almost always sit to pee at home. I find it funny that so many guys think that means something when it just means I don’t want pee all over the floor and the rim and the tank. I also don’t feel I need a 98 decibel exhaust on my motorcycle to feel like a man.


65 posted on 04/08/2025 8:46:56 AM PDT by John Milner (Marching for Peace is like breathing for food.)
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To: Red Badger

66 posted on 04/08/2025 8:53:17 AM PDT by mikey_hates_everything
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To: Red Badger

The “Cornucopia” looks like “Monica” with sharp edges.


67 posted on 04/08/2025 8:53:19 AM PDT by rlmorel ("A people that elect corrupt politicians are not victims...but accomplices." George Orwell)
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To: Red Badger

Dribbling on your own shoes is cured? Asking for a friend who is not named Joe Biden...


68 posted on 04/08/2025 8:54:04 AM PDT by Aut Pax Aut Bellum (I sure am getting what I voted for!)
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To: Red Badger

Just use jugs like the Trailer Park Boys. 😅


69 posted on 04/08/2025 8:54:25 AM PDT by MachIV
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To: Scrambler Bob

I used to go to the Old Boston Garden, and those places to wash hands were frequently used as urinals!


70 posted on 04/08/2025 8:55:05 AM PDT by rlmorel ("A people that elect corrupt politicians are not victims...but accomplices." George Orwell)
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To: Red Badger

Doing it sitting down doesn’t empty everything.

You can only get it empty standing up.


71 posted on 04/08/2025 8:55:36 AM PDT by E. Pluribus Unum (Democrats are the Party of anger, hate and violence.)
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To: AnotherUnixGeek

and don’t forget how badly some “womyn” aim. Will need the new “designed by physics science to prevent splashing” urinals in the “ladies room” too.


72 posted on 04/08/2025 8:56:36 AM PDT by Qwapisking ("The left will rue the day they cheated Trump out of the 2020 election forever" L.Star )
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To: paulcissa

agree! we have citrus that needs watering regularly so told wifey i can fix that. i didn’t say how.


73 posted on 04/08/2025 9:01:25 AM PDT by Qwapisking ("The left will rue the day they cheated Trump out of the 2020 election forever" L.Star )
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To: Red Badger

Couldnt these ivy leaguer business degree sitzen pinklers just have asked real men in the first place?

We told those little homos to stop installing piss sinks instead of proper full length urinals when they started this crap.


74 posted on 04/08/2025 9:03:51 AM PDT by gnarledmaw (If you dont like my sense of humor, please let me know so I can laugh at you too.)
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To: libertylover

Just have to stand back farther and arc it.


75 posted on 04/08/2025 9:05:02 AM PDT by gnarledmaw (If you dont like my sense of humor, please let me know so I can laugh at you too.)
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To: Magnum44

Crumbling vertebrae, pinched nerves. Causes all kinds of strange sensations that keep changing.

Often a numb patch with a row of staples or fish hooks going through it on one thigh and an elf, maybe a chihuahua, that randomly pisses on my calf.


76 posted on 04/08/2025 9:12:34 AM PDT by gnarledmaw (If you dont like my sense of humor, please let me know so I can laugh at you too.)
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To: Pollard

The old bars around here tacked a piece of galvanized sheet to one of the walls. Usually with the pipe just under the right bottom corner and then they bent the left corner up and pulled a bit. You just found the right height and everything happened naturally like you were outside.


77 posted on 04/08/2025 9:17:55 AM PDT by gnarledmaw (If you dont like my sense of humor, please let me know so I can laugh at you too.)
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To: Red Badger

The remains that a lot of men just can’t shoot. The highly trained Secret Service missed an assassin at less than 3 feet.

However California has solved this problem by making the whole world a toilet.


78 posted on 04/08/2025 9:21:32 AM PDT by fella ("As it was before Noah so shall it be again," )
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To: FamiliarFace

Well, there was a supper club around here that covered a wall with rocks and then sent a thin stream of water down it to the trough in the floor. There were some leaves and branches up around the ceiling in there. Maybe they had a similar idea.


79 posted on 04/08/2025 9:22:24 AM PDT by gnarledmaw (If you dont like my sense of humor, please let me know so I can laugh at you too.)
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To: Red Badger

Any research on how to deal with the other bathroom problem - #2 splattering off the rotating ventilator blades? 🤔


80 posted on 04/08/2025 9:22:33 AM PDT by DJ Frisat (If I said something really stupid, chances are I was under the influence of AutoCorrect. 🙄🫤)
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