“Wizz kids” Todd Truscott and Randy Hurd of Brigham Young University’s Splash Lab, a research lab studying the physics of fluids, have been using high-speed cameras to examine exactly what happens to a stream of urine when it hits the toilet.
They’re on a quest against “splashback,” simulating male urination in the lab (since seeing an actual penis urinating is too offensive) to see how exactly you can go about getting it all in the bowl. For the sake of clean bathrooms, clean pants and happy subsequent bathroom-goers. According to Hurd, part of the messiness caused by male urination is due to a phenomenon called Plateau-Rayleigh instability, which causes streams of falling liquid to decompose into droplets. When a guy pees, the urine stream breaks into droplets about six inches away from the urethra exit. “So by the time it hits the urinal, it’s already in droplet form,” he told the BBC. “And these droplets are the perpetrators of the splash formation on your khaki pants.”
The best way to avoid unwanted urine splash seems to be sitting on the toilet, a technique that has been advocated by certain restaurants, Taiwan’s Environmental Protection Administration minister, and one Swedish politician, and shouted down by many corners of the Internet. You’re about five times farther from the bowl when you stand as when you sit, creating a bigger splash, but if standing to pee is essential to your manhood, Hurd says that you can also switch the “angle of attack,” so to speak. Smaller angle between stream and toilet water, less splatter. Even better, hit the porcelain instead of the water, which Hurd says makes the process “a lot less chaotic.”
The Splash Lab will be presenting its research at the American Physical Society Meeting later this month. Now watch this mesmerizing video summarizing the fluid dynamics of urine splatter: