The Reason You Should Never Leave Your Toilet Seat Up

April 10th 2016

Alex Mierjeski

A gaping toilet bowl is never an aesthetically pleasing sight to behold — but there's a much better reason you should always keep your toilet seat down.

It's called "toilet plume," and it's horrifying.

It's unclear how long we've known about the phenomenon, but it's likely been around for a while, at least as long as we've been sitting on contemporary toilets. Essentially it works like this: When you flush, the vortex of water sucking down waste also produces an invisible spray of sorts, imbued with whatever happens to be in the bowl at the time, dispersing it elsewhere in the room.

The aerosolized waste can reach heights as great as 15 feet, one New York University microbiologist told Tech Insider recently. After a good flush, bacteria from the toilet bowl are jettisoned to the far reaches of the bathroom, alighting on all surfaces — the sink, your toothbrush — according to research stretching back to the 1970s.

Things may be improving. Developments in toilet hydraulics, as well as research in recent years, should allay at least some of your concerns about ingesting poo spores.

In so-called "low-flow" toilets, flushes tend to be less vigorous and reduce the amount of delicate scatological mist spritzed out by a flush. But even if you find yourself face to bowl with an older toilet, you can probably breathe easy (but not too deeply).

While potentially infectious aerosols may be produced in substantial quantities during flushing, "no studies have yet clearly demonstrated or refuted toilet plume-related disease transmission, and the significance of the risk remains largely uncharacterized," according to one recent review of existing scientific literature.

That's comforting (throws out toothbrush).