At home, the toilet seat is a closed oval. In an airport, a restaurant or a stadium, it almost always has a gap at the front, like a horseshoe. Most people have noticed it without ever wondering why. The shape isn’t a cost-cutting accident or a design whim: in most of the United States, it’s actually written into the plumbing code.
It’s in the code
Public restrooms in the U.S. are built to plumbing codes, and most of them require an open-front seat outside private homes. According to Mental Floss, California’s plumbing code, for example, states that seats outside dwelling units must be of the “open front type” or come with an automatic seat cover dispenser.
The rule isn’t new. Dan Cole, a technical services manager at IAPMO, the organization behind the Uniform Plumbing Code, told Mental Floss that the requirement first appeared in the American Standard National Plumbing Code in 1955, then in the Uniform Plumbing Code in 1973. Homes are exempt, which is why the seat in your own bathroom is a full oval.
What the gap is really for
The opening has several jobs at once:
- Less contact. The gap leaves room so the most sensitive parts of the body don’t touch a seat that hundreds of strangers have used.
- Easier wiping. Lynne Simnick, IAPMO’s senior vice president of code development, explained to Mental Floss that the opening lets women wipe “without contacting the seat.”
- Less mess. With no seat at the front, there is simply less surface for drips and splashes to land on, which makes the seat easier to keep clean between two cleaning rounds.
- Lower cost. A U-shaped seat uses less material, so it’s cheaper to buy in bulk for a building full of stalls.
Theft is another reason mentioned in Mental Floss: Roger Barry, managing director of the restroom company Healthmatic, said it’s a real problem for public toilets, and in the U.K. some have no seat at all for that very reason.
Why your toilet at home is different
In a private bathroom, the same few people use the same seat, and it’s cleaned on a home routine. Comfort and looks matter more, so manufacturers sell closed oval and round seats, and the code leaves homeowners free to choose. Some people do buy open-front seats for home, often for elderly relatives or for easier cleaning, but they remain the exception.
The limit
The gap makes a public seat a little more hygienic, but it doesn’t make it clean. The shape reduces contact; it doesn’t replace a quick wipe of the seat if it’s wet, or the most important step of all: washing your hands with soap and water before you leave. Codes also vary by state and by building type, so you’ll still find closed seats in some older or private facilities.
Hidden details like this one are everywhere in the bathroom: here is what the tiny dots on toilet paper are for. In the laundry room, few people know what the two holes in clothespins are for. And at home, the best way to keep the bowl spotless is this method against limescale.
A horseshoe instead of an oval: less contact, less mess, and a rule that dates back to 1955. That’s the trick.
