Toilet flush which way

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For more newsletters, check out our newsletters page. The Simpsons episode " Bart vs. Australia ," which involves the oldest Simpson kid getting indicted for fraud in the Commonwealth, starts with a scene in a bathroom. Bart has noticed that the water in the sink always drains in a counterclockwise way; Lisa informs him that, in the Southern Hemisphere, it drains the other way. 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. Well done internet. Using a kids' portable pool they proved that a phenomenon known as the Coriolis effect , where the earth's rotation causes things moving in a straight line to follow a circular motion, does hold water.

The water in the pool in the Northern Hemisphere drained in a counter clockwise direction while the pool in Australia did the opposite. It's bogus! Today I learned that while the Coriolis effect is significant for hurricanes, it's not strong enough to make toilets flush in different directions at different points on the Earth.

The real cause of "backwards"-flushing toilets is just that the water jets point in the opposite direction. Mind blown. Mind blown even more because this was the inciting event on a Simpsons episode , and everybody knows cartoons are never wrong.

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.

Indeed, the term cyclonic not only means that the fluid air or water rotates in the same direction as the underlying Earth, but also that the rotation of the fluid is due to the rotation of the Earth. Thus, the air flowing around a hurricane spins counter-clockwise in the northern hemisphere, and clockwise in the southern hemisphere as does the Earth, itself. In both hemispheres, this rotation is deemed cyclonic. If the Earth did not rotate, the air would flow directly in towards the low pressure center, but on a spinning Earth, the Coriolis force causes that air to be deviated with the result that it travels around the low pressure center.