WTF Weds: Water Goes Down the Drain the Same Way in The Southern Hemisphere

Posted on
May 15, 2013

The sink in our hotel in Australia. SPOILER: the water went straight down.

I have some disappointing news.

Are you sitting down? You should probably sit down. You aren’t going to like what I have to say. This piece of news is up there with learning that Santa and professional wrestling are not real (if I just broke the news about either of those things to you just now, then I am very, very sorry. Life is easier when you believe that men come down your chimney armed with presents, and that karmic piledrivers do happen to bad people).

Instead, my sad revelation is this: the direction in which water goes down the drain (clockwise or counterclockwise) has absolutely nothing to do with where you are on the planet.

I realize that this is in direct opposition to everything that we were taught in 6th grade science class. If you are anything like me (pear-shaped, bad at math, and in your 30s), it was instilled in you at an early age that water goes down the drain in a counterclockwise direction north of the equator, and in a clockwise direction south of the equator.

This phenomenon, which I never bothered to test, was explained as being a result of the Coriolis Force.

Are you ready for some potentially inaccurate, woefully explained amateur physics? Wonderful! (Also, I dare you to find another travel blog that tackles stuff like this. THERE ARE PROBABLY NONE. Why? Because other travel bloggers don’t have the time or the inclination to flush their toilets repeatedly and record the direction of the putrid water. But I do, folks. I do.)

Let’s talk about the Coriolis Effect, which is a result of the earth’s rotation.

Here’s how it works (note: this example is totally not sound and could not be replicated in the real world, but I need you to work with me, people):

Let’s say you shoot a canon ball from the North Pole, with the goal of hitting Florida, which is directly south of you (Don’t worry – I lived in Florida for the better part of a decade, and can assure you: it has it coming). The canon ball will obviously take a while to get to Florida from the North Pole, and during that time, the earth will have rotated.

Of course, we’ll have rotated, too, but our canon ball, which is airborne, won’t. Since the earth is rotating, Florida will actually be further to the left of where it was when first shot the canon. Our projectile will land to the right of our intended target. Instead of hitting Florida, it’ll plunk down somewhere in the Gulf of Mexico.

Because of the Coriolis Effect, it seems to those of us on earth as though our canon ball has shifted and moved to the right (really, it has moved in a straight line. It’s the earth that’s moving). This is known as the Coriolis effect. In the Northern hemisphere, it causes objects to seem to deviate to the right, and in the Southern hemisphere, objects seem to deviate to the left.

Okay, are you still with me? No? That’s good, because I’m sort of confused, too.

The Coriolis Effect can be seem most notably be see in anything that’s hovering above the surface of the earth and moving long distances. So planes, missiles, and air masses can all be influenced by the Coriolis effect. And because of high and low pressure systems within an air mass, you’ll often get spiraling that results from this. If you ever see photos of hurricanes or low-pressure systems from space, you’ll notice that north of the equator, they move counterclockwise. South of the equator, they move clockwise.

What about if you are on the equator? Well, that’s where it gets crazy: hurricanes don’t form within 5 degrees of latitude of the equator because the Coriolis Effect isn’t strong enough.

When I was small, I was taught that you could see the Coriolis Effect in everything, including our toilets and sinks. Hell, my brother even had a book as a kid called Impossible Unless You Know How by Shari Lewis (yes, she of Lambchop fame) that corroborated this fact.

But now that I’ve visited the Southern hemisphere on four separate occasions, and having flushed numerous toilets while I was there, I can definitively tell you: Shari Lewis and my science teacher were both full of it.

Shari Lewis Lambchop

Here’s why: There is simply too little water (and it drains far too quickly) for the Coriolis Effect to be seen on a scale as small as a bathroom basin. The direction that the water goes down is determined by the shape of the bowl and the direction of the jets shooting water into it. Consequently, you can find toilet bowls that flush clockwise or counterclockwise in both hemispheres.

So why, then, does everyone seem to think that water goes does one way in Northern hemisphere, and another way south of the equator? Often times, it’s simply confirmation bias. We believe something to be true, so we only notice evidence that supports that fact. We ignore evidence to the contrary.

As for me, I’ve gotten into the habit of putting the lid down whenever I flush. It’s more hygienic. And that way, I can pretend the water is moving in whatever direction I want.

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