Thanks to physics, urinal splashing in men’s bathrooms reduces by 95%

If you have ever entered a public men’s restroom, you are aware of a frequent and gross problem: urinal splash back. When the typically designed urinal is in use, it’s not uncommon for droplets spraying and splashing onto the floors, walls, and the pants of the users. This has caused not just a health hazard but great expense and water use in cleaning up these messes so frequently. Thanks to physics and engineering from the University of Waterloo in Canada and Weber State University in Utah, this splashing problem will be flushed to the past and create cleaner men’s rooms.

Current methods to clean or prevent urinal splashing are better than nothing, but still aren’t very efficient. Targets in the urinal, absorbing mats, and frequent cleaning schedules don’t address the root of the problem. According to the published study from UW and WSU, there are approximately 56 million urinals in businesses, government buildings, and other non-residential areas across the United States, leading researchers to conclude that more than 350,000 liters of urine splash onto their floors every day. That leads to a lot of time, money, and water to clean up pee.

But the engineers found a solution using physics and geometry while making slight changes to the design of the typical urinal. Through examining why splash back occurs, they found that the angle at which the liquid stream hits the urinal surface was the key culprit. Through trial and error, mathematics, and controlled experiments, they found that when a stream hits below a 30-degree angle, splash back dropped by 95% compared to usual perpendicular impact.

With this in mind, the engineers then designed a urinal which ensured that all the surfaces would be hit at a 30-degree angle or lower regardless of a person’s poor aim or their height. They developed two effective designs, which they named the Cornucopia and the Nautilus. While both designs were more effective at reducing splash back than common commercial urinals while still being made from porcelain, the Nautilus was more practical in that its lower profile allowed small children and wheelchair users to also use it without needing to adjust installation for height.

By testing the usual urinal models, engineers came up with the Cornucopia and Nautilus models.Photo credit: PNAS Nexus

While it’ll take time before the Nautilus version of the urinal replaces the other versions, there are still ways to make time in the public men’s room a more pleasant experience. If you do end up making a mess in a public restroom, swallow your pride and do your best to clean it yourself. If it’s a bigger job than what paper towels and water can handle, let the staff know so you won’t leave a dirtier restroom behind.

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Another way to make the public restroom more accommodating is to remember that it’s still public. That means allowing other folks in the restroom as much personal space and privacy as possible. It also means not taking phone calls in the restroom either. In fact, don’t even use your phone at all, as texting while you do your business makes you stay inside longer, forcing others to wait.

All of this shows that it takes proper etiquette, geometry, physics, and engineering to make a dirty but necessary job less dirty.