After cars and video game consoles, fancy toilets just might be Japan’s best-known technological achievement. In a society that prizes cleanliness, it’s no surprise that being able to push a button and have a warm stream of water wash your backside has become one creature comfort many can’t do without.

As such, just about everyone in Japan is happy to have a washlet, as bidet-equipped toilets are called here, in their home. Some people can’t help but wonder, though, if they’re spraying someone else’s fecal matter back up on themselves when they use a washlet in a public restroom.

As with most technological developments, washlets enjoy widespread popularity among Japan’s younger population. In a survey of 8,650 people between the ages of 20 and 34 (100 percent of whom assumedly poop), 67.7 percent said they prefer having a toilet with a bidet function, and 25.1 percent called it an absolute necessity.

Warm-water washlets first hit the market in 1980, and since then more than 40 million of the squirting thrones have been sold. While initially customers were primarily private residences and high-end hospitality facilities, the technology has since trickled down to where it’s not uncommon to find washlets in train stations, offices, shopping centers, and casual restaurants.

But while most of Japan is fine using their own private washlet at home, some of them aren’t too comfortable asking a public toilet to hose them down. How come? Well, it has to do with the relative heights of the nozzle and the backside it’s aimed at.

The nozzle is set in the bottom of the bowl, and squirts water up towards the user’s butt. The water sluices through, then falls back down into the bowl to be flushed away. Some people worry, though, that a portion of that runoff might fall back onto the nozzle.

▼ Here’s a crude diagram, because ironically a detailed one would be even cruder.

WC 1

If any of the water/poo mixture does land on the nozzle, that would mean that whoever uses the washlet next isn’t just getting blasted with cleansing water, but with a mild turd solution brewed by the internal plumbing of the toilet’s previous occupant.

Thankfully, medical data suggests this isn’t happening. Something as unhygienic as getting old poo shot at your bare backside seems like it would be an effective recipe for infection, but even with those 40 million-plus washlets we mentioned above being in service, there hasn’t been a single case reported where the cause of illness was determined to have anything to do with a toilet bidet function.

And while it’s probably not the most pleasant part of their work day, toilet designers spend quite a bit of time thinking about these exact issues, configuring and positioning the components of their washlets to prevent this sort of gross incident. Research has shown the optimal angle for reducing the chance of splashback is 43 degrees, and almost all modern washlet nozzles are equipped with a self-cleaning function as an extra precaution to ensure they stay sanitary.

But while it’s unlikely the nozzle will get doused with runoff, the same can’t always be said about the toilet seat itself. Depending on the strength of the squirt and how exactly the user is sitting, sometimes the bidet function can leave drops of water on the seat, and good manners dictate grabbing a sheet of toilet paper and wiping it off for the next person (preferably using the sanitizer that’s becoming more common in public restroom stalls in Japan). After all, most people would say that if the price of a clean butthole is wet butt cheeks, it’s kind of a wash.

Source: Naver Matome
Washlet Poo Splashback Diagram ©RocketNews24