If you’ve ever used a public restroom in the United States, you’ve probably noticed it: toilet seats that are open at the front, leaving a distinctive U-shape. For years, this quirk was seen as an American oddity. Now, however, the design is popping up in France too—in airports, train stations, and restaurants.

At first glance, it looks like a matter of style or cost-saving. But the truth is more surprising: it’s not just design, it’s regulation.

A Rule Written Into Law

In the U.S., open-front toilet seats have been the norm since the 1950s, when the Uniform Plumbing Code made them mandatory in all public restrooms—unless disposable seat covers are provided.

The reasoning wasn’t aesthetic. It was hygiene. By cutting out the most exposed part of the seat, the design reduces the chance of direct contact with splashes, makes cleaning faster, and limits the spread of bacteria in high-traffic spaces.

What Science Says

Research backs this up. A 2015 study in Applied and Environmental Microbiology tracked microbial growth in public restrooms after deep cleaning. Within just eight hours, bacteria—including fecal microbes from toilet flush aerosols and skin bacteria from users—had recolonized surfaces. Some strains, like Staphylococcus and MRSA markers, were still present hours later.

The study highlighted one hotspot in particular: the front of the seat. That’s exactly the area reduced by the U-shape, making the design both practical and protective.

More Than a Quirk

The cut-out shape isn’t only about germs. For women, it makes intimate hygiene easier. For all users, it minimizes splashback. And for staff, it simplifies cleaning the messiest part of the toilet.

What once seemed like a peculiar American standard is now spreading abroad, with France gradually adopting the design. Quietly but effectively, the U-shaped seat is turning from curiosity to common sense—an understated example of how small details can make public spaces cleaner and safer.