Which way toilet flushes

Indeed, a colleague of mine, who witnessed the performance first hand and knew it was a cheat, was not able to spot how the fraud was perpetrated. It is an interesting sidelight that when back on the bus, he informed his fellow tourists that they had just witnessed fakery the Earth did not cause the rotation they had just seen there was widespread disappointment.

The tourists preferred the fantasy to the reality. Fraser proceeds to explain how you can fake it yourself. 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.

But in your typical toilet or sink, the Coriolis force is so small as to be undetectable relative to other forces. Even holding a bowl of water and turning around introduces sufficient spin to get things going in one direction or another. Go to your bathroom now and observe water going down the drain -- any drain you want. Depending on the efficiency of your plumbing, you may need to stop up the drain, fill the basin, then unplug it and wait.

It might also help to have something lightweight floating in there, to mark any motion -- a few bits of tissue may work, or a matchstick or two. Observe whether the draining water forms a clockwise or counter-clockwise spiral. Go ahead, I'll wait. 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.

Get smart. Sign up for our email newsletter. Likewise, the rotation of the earth gives rise to an effect that tends to accelerate draining water in a clockwise direction in the Northern hemisphere and counterclockwise in the Southern. In your tub, such factors as any small asymmetry of the shape of the drain will determine which direction the circulation occurs.

Even in a tub having a perfectly symmetric drain, the circulation direction will be primarily influenced by any residual currents in the bathtub left over from the time when it was filled. It can take more than a day for such residual currents to subside completely. If all extraneous influences including air currents can be reduced below a certain level, one apparently can observe that drains do consistently drain in different directions in the two hemispheres.

Toilet Bowls drain however they're designed to circulate water. There you have it. Another myth, going down the The water in the pool in the Northern Hemisphere drained in a counter clockwise direction while the pool in Australia did the opposite.

This complex phenomenon however, has nothing to do with the way your toilet flushes -- that's just down to the design. Drain all the sinks and tubs in their house and see which way they swirl.