This Is Why Public Toilet Seats Are Shaped Like a U

Have you noticed that the toilet seats in public restrooms look a little different than your toilet at home?

It might be something that you miss unless it’s pointed out to you. Next time you go to a public bathroom, take a look before you sit down on the toilet seat. You won’t encounter an oval or circle, but something incomplete; a U. While you’re in there, don’t forget these public restroom etiquette tips.

This is an open-front toilet seat, and thanks to the American Standard National Plumbing Code, it’s the go-to for most public restrooms. This code was created in 1955 and further cemented by the Uniform Plumbing Code in 1973 by the International Association of Plumbing and Mechanical Officials (IAPMO).

The code states, “Water closets shall be equipped with seats of smooth non-absorbent material. All seats of water closets provided for public use shall be of the open-front type.”

The rationale for both of these rules comes down to hygiene. With an open front, there’s less surface area that can make incidental contact with your nether regions. But what about the toilet seat covers you can use? Unfortunately, those don’t offer as much protection against germs as you think they do.

They were also designed with women in mind, according to Lynne Simick, the senior director of code development at IAPMO. The gap in the seat is designed to “allow women to wipe the perineal area after using the toilet without contacting the seat,” she tells Slate. Simick notes that the design also benefits men. She says an open-front seat “eliminates an area that could be contaminated with urine” and also “eliminates the user’s genital contact with the seat.”

Now that you know why the public toilet seat is shaped the way it is, learn which public bathroom stall is the cleanest one you can use.