Could this urinal design help save the planet?

Engineers at the University of Waterloo are hoping to cause a stir – er, rather avoid – with a prototype they believe could revolutionize men’s toilets.

They’ve created a tall, slender urinal, inspired in part by dogs and a seashell, that aims to solve a century-old problem that has long given the men’s room its reputation for being damp and gross.

By determining an ideal impact angle – the angle between a jet of liquid and a solid surface – the research team was able to design a container that reduces the spray of urine to almost nothing.

And while it sounds like a bit of engineering fun, the benefits are real. Not only could innovation waste time and resources on cleaning, but it could also save pants, shoes and pride.

Team leader Zhao Pan is an engineering professor at Waterloo and leads the Pan Lab, described as “an interdisciplinary and collaborative kitchen for fluid physics”. Urine may not be the first liquid anyone would consider the object of study in an academic setting, but, Pan said, splashing “isn’t very pleasant and it’s embarrassing , even if you don’t care about hygiene”.

And, more importantly, he noted, it’s a matter of durability, of reducing reliance on water, chemicals and human labor to mop up the flaw of a device whose design is not hasn’t really changed much in 100 years.

Dr. Zhao Pan, professor of engineering at the University of Waterloo.  He and his team designed a new urinal to reduce splashing.

Named Nauti-loo, referencing the nautilus shell that inspired the curved shape with a little pun on toilets and Waterloo, the prototype prevents droplets from spraying, regardless of the size of the user or the vagueness of its purpose.

The results – a research paper is still pending – were presented recently at the American Physical Society conference in Indianapolis. Pan, along with faculty and students from Waterloo and Weber State University in Utah, have been working on the project for nearly five years. He said conference attendees were amazed at how fun the research was, but few identified the cutting-edge physics behind it.

Initially, the team had to ask a fundamental question about the physics of droplets: at what angle of impact would the splashes not occur?

They considered the way a dog pees – raising its hind leg to urinate against a tree instead of directly on the ground. “By doing this they reduce the angle of impact of the jets (less splash),” Pan said. “So in that sense, dogs are smarter than males.”

Using water to mimic bodily fluids and a pressurized pumping device to mimic the male orifice, the team conducted numerous experiments on an inclined surface to determine the optimal angle for the least amount of splashing. They found out it was 30 degrees or less.

Tests were then carried out on four types of urinals. One was a replica of the Bedfordshire style urinal made famous by the artist Marcel Duchamp at an exhibition in New York in 1917. Another was a version purchased from American Standard which can be found in just about any restaurant or bar. And the last two were prototypes designed by the team to have surfaces in which the path of urine would intersect at or below the set angle. (A third prototype was created but was not tested.)

The prototypes, made from high-density foam and covered in epoxy, significantly outperformed existing designs, Pan said.

Urinals haven’t changed much in their long history. Ancient receptacles and troughs provided the first reservoirs, but the “modern” urinal – whose origin is somewhat sketchy but which some attribute to a patent by Andrew Rankin in 1866 – did not stray from the bowl-like form. There have been innovations to make urinals odorless, touchless, and waterless, but the splashback has largely remained.

“There’s very little variation in what you see,” said John Engel, who as director of marketing for installation services at Cintas, the company behind the famed annual best toilet contest in Canada and the United States, has “spent more time in toilets than I ever thought…and yes, they can absolutely be gross.

“The notion of splashing is real. You’ll hear (people say), thank goodness I didn’t have khaki pants or something that would show. It never ceases to amaze me that you see moisture on the floor and think, “Who did that or is it the light fixture?”

Cintas, which provides uniforms and cleaning products, also sells mats to place under urinals, said Engel, who noted that other companies also sell products to face backsplashes. “The business world recognizes an opportunity fairly quickly. So I think it’s either the urinal manufacturers or the people who make (splash) screens, they’re both trying to address this.

Two companies, one that manufactures urinals and the other a large supermarket, have expressed interest in the Nauti-loo. Pan would like to see it installed on the Waterloo campus as an educational tool to show students how the application of STEM research improves our daily lives.

Now if only someone could solve the queue for the women’s restroom.


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