I gotta go back and check this again now that Cecil has stated water flows the same way no matter which country we’re in. I read somewhere (way before I heard of Cecil) that water in the sink, bathtub etc flows anti-clockwise if you’re in the southern hemisphere so since I go down to Australia at least twice a year, I made sure to check and it did, indeed, flow the other way! Now, the rest of the year I live in the Northern Hemisphere so I could check out this claim. I even showed it to other people who never noticed it before. So, I am kinda weorried now that there may be something wrong with the plumbing in the houses I lived in. Anyway, I’m going to check this one more time when I’m in Australia again next April. You know…I really believed this Cecil guy knew everything!
Link to Cecil’s column:
Please note that Cecil is NOT saying that the effect doesn’t exist. He’s saying that it can only reliably affect very large movements (like hurricanes.) On a small level, like a sink or tub, small perturbations (shape of the tub, direction of flush, hand motion in the tub, etc) can overwhelm the coriolis effect.
Thus, in the experiment he mentions, it was easy to get the liquid to flow counter to the coriolis direction. When all other attributes were eliminated, the water would flow clockwise in the southern hemisphere, counter-clockwise in the northern. But the process of eliminating all other effects is not trivial.
Toilets, for instance, usually push the water in one direction or another, and that would have FAR more impact than the coriolis effect. If you fill up a tub with water and then open the drain, there is residual motion to the water (from the process of filling the tub) and that would have more impact than the coriolis effect. If you fill up a tub with water, let water sit for many, many hours to lose all residual motion, and then open the drain, any irregularity in the shape of the tub would have more impact than the coriolis effect. Finally, if you have a perfectly balanced/evenly constructed tub, fill it with water, let the water sit for many, many hours to lose all residual motion, and then open the drain, you will PROBABLY see the coriolis effect. (The hedge of saying “probably” means that any other small influence – like wind, say – could possibly negate the coriolis effect.)
This is also to say that doing the experiment once is meaningless – after all, there’s a 50/50 chance you’ll get the coriolis direction if it were only probabilistic. And doing the experiment with one tub only is meaningless – a distortion in the shape of the tub, undetectable to the naked eye, could effect the result.
So, you’ll need to do dozens of trials with dozens of tub, and collect all that data, and report back to us. I, for one, would be very curious to see such an experiment.
No toilets, they have a direction of flush. Large sinks or tubs. And be sure to let the water sit for a couple of hours to be sure there’s no residual motion (you might put some little floating sticks or toys in the water and wait until they’re motionless in the center – motionless against the edge may mean there’s a small current towards that edge.)
Hmm, I just checked and my kitchen sink drains clockwise, but my bathroom sink drains counter-clockwise. Therefore, the only logical conclusion is that the equator bisects my house here in Chicago.
(And, no, Cecil didn’t say that “water flows the same way no matter which country we’re in.” It can flow either clockwise or counter, depending on the design of the sink and other factors. But not because of the coriolis effect.)
I lived in New Zealand for eight years, and the water went clockwise or counter-clockwise depending on all sorts of different influences. Even if you have a tub of perfectly still water, the mere action of pulling out the plug can change the way the water will flow!
The interesting thing here is that your experiment actually backed up what Cecil said. If the coriolis effect did outweigh other influences on the water in the sink, it would flow clockwise in Australia and anticlockwise up north. The fact that you observed it to flow anticlockwise in the Great Southern Land means that something other than the coriolis effect prevailed.
For what its worth, my daughter and her husband spent 2 weeks in Brazil and told me the toilets and bathtubs drain opposite to what it does north of the equator.
They probably based that conclusion on observing the bathtub and toilet in their hotel room. One (or even two or three or four) sample doth not a statistic make. If there’s a 50/50 chance (the water will go either clockwise or anticlockwise), then it would not be unusual to get three or four “heads” in a row.
Especially true of toilets. The flush action in toilets is rarely straight down, water is usually flowing out in some slight direction (so as to circulate around the bowl and provide some washing action.) And, note that the same manufacturer might make all flows in the same direction… and there ain’t THAT many toilet manufacturers.
Heh, heh. If I were a toilet manufacturer (and that is something I have always wanted to say) I would be tempted to make two different bowl molds, one to ship to the Northern Hemi, one to the South. Just to confuse the issue.
And how do you know they don’t? 
Oooooh, and make them opposite of the Coriolis Effect for each hemisphere!