Which direction toilets flush

Now check all the other drains you can find. Do they match? In my admittedly unscientific testing just now, one sink drained clockwise, the other counter-clockwise, one didn't have an easily observable spin it's small , and the toilet was also counter-clockwise, clearly due to the position of its water jets. There you go: science in action. Via Steven Frank , via Snopes. Note that we covered this topic back in as well. Toilet image via Shutterstock File under "News to Me": you know that old story about how northern hemisphere toilets flush counter-clockwise, and southern hemisphere toilets and buckets, drains, and such flush clockwise, due to the Coriolis effect?

Let's Talk Science So there is indeed a Coriolis effect , and we see it on grand scales -- hurricanes in different hemispheres tend to rotate in different directions, because the underlying Earth is spinning, and the effect is exaggerated as you move farther from the equator. Fraser explains: On the scale of hurricanes and large mid-latitude storms, the Coriolis force causes the air to rotate around a low pressure center in a cyclonic direction.

The Pole to Pole Problem In tracking down where this drain-direction myth originated and how it got so firmly lodged in the heads of people like me, many sources discuss the otherwise awesome Michael Palin documentary Pole to Pole , in which Palin visits the equator in Kenya and observes a tourist trap in which a man "demonstrates" via fakery the draining of water in different ways on the equator itself, and just north and south of it.

Again, Fraser has a good write-up ; here's a snippet: [T]he faker must be forcing the rotation by other means, and by a sufficiently unobtrusive way that the busloads of tourists do not spot the means. The Plot Thickens According to various sources , it is possible to demonstrate a Coriolis effect on water on a small scale, but only under extremely controlled circumstances -- involving predictably shaped water vessels, long periods of time of waiting for water to become as still as possible, carefully removing a stopper in the bottom of the vessel without adding spin, and other such crazy stuff.

Bart doesn't believe her. To find out for sure, though, he calls a number in Australia—collect—and … hijinks ensure. The idea that water rotates differently in the different hemispheres is a long-standing one.

Long before seeing that Simpsons episode, I'd heard it, and assumed it to be true. It sounds true. Just like Lisa explains to Bart, the Earth is subject to Coriolis forces , which determine how moving objects are deflected off the inside of rotating objects—wheels, circular containers, those kinds of things.

Applied to Earth's rotating sphere, the Coriolis effect accounts in part for why, say, hurricanes and cyclones rotate the way they do.

The storms rotate c ounterclockwise in the Northern Hemisphere and clockwise in the Southern. But you will find that the faucet is almost always off center or that there is some other asymmetry in the sink.

As a result, filling the sink consistently gives it some net rotation in the same direction, which you see as the normal direction of evacuation. Toilets will always drain and fill the same way, for the same reason. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue.

See Subscription Options. Discover World-Changing Science. Brad Hanson, a staff geologist with the Louisiana Geological Survey, presents the argument of why--in theory--water going down the drain would indeed spin in different directions depending on which hemisphere you're in: "The direction of motion is caused by the Coriolis effect. Decker, professor emeritus of oceanic and atmospheric science at Oregon State University notes, however, that the Coriolis effect may actually have little to do with the behavior of real-world sinks and tubs: "Really, I doubt that the direction of the draining water represents anything more than an accidental twist given by the starting flow.

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