By Mark Jones
I’ve long been fascinated by the observations underlying the inspiration, the eureka moments leading to invention. But inspiration from a urinating dog came as a surprise.
A recent study on designing a splashless urinal made — and excuse the pun — a bit of a splash. Headlines such as “Physicists make a splash with a urinal that doesn’t” dragged me in. I was correctly skeptical of physicists studying urinals. The study was published by engineers, not physicists. Engineers use physics. That doesn’t make them physicists any more than using words makes me a linguist. The inventors got labeled as physicists because they presented the work in a fluid dynamics section at an American Physical Society meeting.
Dogs and nautilus shells are cited as their inspirations. Dogs do not suffer from splash-back when urinating according to the work. The dog’s leg lift creates an angle that keeps the dog’s belly fur dry (an observation I cannot independently confirm). Canids are one of a very tiny set of animals where leg lifting for urination is common, and only for half the population. Inspiration would have been missing had the inventors been cat people or exposed only to female dogs.
Inspired by the urinating dog, studies and computer models led to understanding of urinal splash. Gained understanding led to design of two designs, dubbed Cornucopia and Nautilus, that don’t splash. The study and designs were published in the academic literature, by the National Academies no less.
Urinals are infrequent topics in the academic literature. “The Urinal Problem” offered a mathematical solution to making urinal choice while optimizing privacy. In a title more befitting physicists, there was “Creating a urine black hole.” Rather than designing a completely new urinal, these inventors found inspiration in the water capturing moss Syntrichia caninervis. Structure of the plant causes impinging streams of water to flow into the plant rather than being deflected. Duplication of the structure led to development of splash-free surfaces. Shaped into a urinal pad, any urinal can become splash-free.
An engineer wonders about urinal styles. Image created with AI.
The moss inspired an issued U.S. patent. The patent literature is considerably more populated than the academic literature. It shows extensive innovation around urinals. Keeping urine off the floor is an active area. Poor aim and splash are both implicated as sources of floor contamination. Aad Kieboom and Jos van Bedaf created the urial fly at Schiphol Airport in the 1990s. Providing a target, in the form of a fly decal in the urinal, led to a 50-80% reduction urine on the floor and 8% reduction in cleaning cost. Patents using flexible bristles to prevent urine splashing dates back at least until 2006, predating the urine black hole by more than a decade. The first screen came to market in 2010. Today, many splash reducing products are on the market. Screens currently on the market claim 97% reduction in splash, not as good as the 98.6% reduction in the newly designed Nautilus, but pretty close. Screens containing deodorizers address issues of both splash and smell.
Benefits of urinals and of keeping urine in them are many. Urinals are more space efficient and use less (or no) water. Some suggest urine should be valued as fertilizer. Urinals allow urine collection separate from other waste. Perhaps the biggest advantage is speed, as urinals have higher throughput than toilets.
Throughput is driving innovation in urinal design, especially in the design of urinals for those that don’t typically stand to pee. One company claims 90% of the lines for women’s restrooms are for those seeking only to pee. Using their urinal is 6 times faster. The innovation is said to dramatically shorten restroom lines at large outdoor festivals.
Urinal technology offers something for everyone. My initial skepticism about physicists researching urinals led me to investigate a richer field than I expected. A restroom visit today while wearing shorts clearly illuminated poor urinal design and made me wish for a splashless screen. The urinal fly, splashless screens and splash-free designs are all innovations implemented in my lifetime. I don’t know what the urinal future holds, but it seems destined to be less splashy and more inclusive.
Filed Under: Commentaries • insights • Technical thinking
