Urination flow and the Rights of Toilet-Users
Every once in a while I come across a story that seems so bizarre that I like to borrow from it to blog on a topic everyone wants to better understand. Today it is that U.S. physicists have studied the fluid dynamics of urine "splashback" - and found tips to help men and women with their accuracy and hygiene.
Using high-speed cameras, the team filmed jets of liquid striking toilet walls and studied the resulting spray. Splashback was low when the jets were used close up with a narrow "angle of attack", said the Brigham Young University team.
Have you stopped laughing yet?
The work is led by Professor Tadd Truscott and Randy Hurd of the "Splash Lab" at Brigham Young in Provo, Utah, who jokingly refer to themselves as "wizz kids".
"People ask me, are you serious? I tell them yes – it’s a real problem," Professor Truscott told BBC News in the UK. "We've all been in disgusting toilets with puddles on the floor - these places are a breeding ground for bacteria."
I was astounded to learn that the detergents used to clean hospital toilets could actually increase the spray of disease-causing bacteria, by reducing the surface tension of water, according to a recent study. Now I’m laughing somewhat uncontrollably. How can hospitals be so oblivious to the splashback effect? This is a scandal waiting to happen.
According to the researchers, splashback was heightened by a phenomenon known as Plateau-Rayleigh instability, where a falling stream of liquid breaks up into droplets. "The male urine stream breaks up about 6-7 inches outside the urethra exit," Professor Hurd explained. "So by the time it hits the urinal, it's already in droplet form. And these droplets are the perpetrators of the splash formation on your khaki pants."
His advice? "The closer you are the better. If you can get stream impact with the porcelain, it's a lot less chaotic." Of course, in a domestic bathroom, distance from the toilet is governed chiefly by one variable: "to stand or sit". "People are always arguing over which is better. Because when you sit close, you're also closer to getting wet," said Professor Truscott.
Did you know that in in Germany there is a derogatory term 'sitzpinkler' for a man who sits down to pee. It means he's kind of a wuss.
The professors also established a research-oriented question of whether sitting down is really effective. The null hypothesis would be that it is not. To compare the two positions, the scientists gave rulers to their friends and sent them into the toilet.
"It turns out you are five times as far away when you stand up - and that's a pretty significant difference in impact velocity for those droplets of urine," said Professor Hurd.
Impact with the toilet water is captured in a video, but I refuse to go there. If you must, here is the link to the You Tube video on ‘The Science of Pee Splashback.’
I’m always looking for the ethics angle and pee splashback is no different. Do we have an ethical obligation to avoid pee splashback when we use the toilets? What are the rights of those who use the toilets after us with respect to cleanliness of the toilets? Do the benefits of relieving oneself quickly exceed the harms to those who come after use and use those toilets inundated with splashback? Finally, is it ethical to call someone a sitzpinkler simply because they sit to pee? These are just some of the burning ethical questions that must be dealt with before passing legislation to make it a misdemeanor to create pee splashback.
Yes, even the ‘ethics sage’ can go off the deep end in a blog. I guess the moral of the story is we need to laugh at ourselves and behaviors every once in a while because there are so many negative things around us that cause consternation.
Blog posted by Steven Mintz, aka Ethics Sage, on November 14, 2013