Wait, so it’s NOT true that Toilets Flush Opposite in the Southern Hemisphere?

Correct! This common myth about toilets flushing in opposite directions in the Northern and Southern Hemispheres is simply not true. You may also have heard this myth being applied to water spiraling down a sink drain and other similar phenomena. In fact, if you visit an equatorial town, you may even find people who, for a small fee, will demonstrate such changes as they step back and forth across the equator. But they are faking you out, using tricks to change the direction of the water flow.

You probably realize that this myth arises from the fact that hurricanes and other storms really do spiral in opposite directions in the two hemispheres. But remember that this is a result of the Coriolis effect , which is noticeable only over large distances (at least tens to hundreds of kilometers). The Coriolis effect is completely unnoticeable for objects as small as toilets or drains.

So what actually determines the direction of water flow in a toilet or sink drain? The answer is a combination of the shape of the drain and the direction in which the water flows into it. That is why, if you actually watch toilets flushing or sinks draining, you will see that some have water swirling down clockwise and some counterclockwise , no matter where you are located on Earth. Indeed, if you use a hose to spray water into a sink, you can easily make the water spiral down in either direction just by holding the hose at different angles.

Bottom line: The Coriolis is real and has important effects on air (and other objects) traveling long distances on Earth, but it has no noticeable effect on small-scale motions like those in toilets or sinks.