Why does the toilet flush "counter-clockwise" in Australia and some parts of New-Zealand?

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markus0032003

Theorethically if you have a perfectly symetric shaped toilet, the Coriolis effect would be responsible for the direction the toilet flushes.
But the effect and the amount of water is way to small to really influence the way your toilet flushes, the shape of your toilet and the plumbing in fact are responsible.

Then if it does flush counter-clockwise it is related to the make of the toilet. But that should be nearly evenly distributed between clockwise and counter-clockwise flushing toilets.

Here the relevant explanation:
A popular misconception is that the Coriolis effect determines the direction in which bathtubs or toilets drain, and that water always drains in one direction in the Northern Hemisphere, and in the other direction in the Southern Hemisphere. This myth has perhaps been perpetuated by the Simpsons episode "Bart Vs. Australia," in which protagonist Bart Simpson has a young Australian boy confirm that his toilet water in the Southern Hemisphere spins in the opposite direction from Bart's own in the Northern Hemisphere. The myth is also propagated by the plethora of websites claiming that this fallacy is true[1]. Strangely, many of these sites claim that drain water spins clockwise north of the equator, and counterclockwise south of it, which is reversed from direction of spin that would result from the Coriolis force, if it were a determining factor.

In reality, the Coriolis effect is a few orders of magnitude smaller than various random influences on drain direction, such as the geometry of the sink, toilet, or tub, and the direction in which water was initially added to it. Most toilets flush in only one direction, because the toilet water flows into the bowl at an angle. If you shot water into the toilet basin from the opposite direction, the water would spin in the opposite direction[2].

This is less of a puzzle once one remembers that the Earth rotates once per day but that a bathtub takes only minutes (and a toilet only seconds) to drain. When the water is being drawn towards the drain, the radius with which it is spinning around it decreases, so its rate of rotation increases from the low background level to a noticeable spin in order to conserve its angular momentum (the same effect as ice skaters bringing their arms in to cause them to spin faster).

tentofield

The Coriolis effect is caused by the rotation of the Earth about its axis. The earth goes round once per day so Coriolis gives a rotation of one revolution per day.

Imagine standing on the south pole. The earth is revolving so in 24 hours you face through 360Â°. Now imagine standing on the equator looking at the south pole. In 24 hours you do not change your view, even though the Earth is rotating so you are not rotating. Coriolis is therefore zero on the equator and at a maximum at the poles. Another way of loking at it is that it is proportional to the sine of the latitude which makes it zero on the equator and greatest at the poles.

We have established, therefore, that Coriolis is a weak force that makes things turn through 360Â° in 24 hours. Water going down drains is revolving much faster than that. The shape of the container and currents in the water determine which way the water spirals. We can see the effect of Coriolis on mesoscale systems such as seabreezes and large thunderstorms but smaller vortices such as dust devils and water going down drains are affected by other things and spiral both ways in both hemispheres.

By the way, nothing goes "counter-clockwise" in Australia. here things go "anticlockwise".

Steve W

its the coriolous effect , its different, north and south of the equator!

ELM

It is to do with the gravitational pull of the earth. It is opposite to the Northern Hemisphere because it is on the other side of the earth.
I believe some of the v. posh resorts have a mechanism that makes it go the northern hemisphere way just so Americans can feel at home!

the atomic penguin

your from america arent you

Driver T

It doesn't.
It's an urban myth that has been around for 150 years or so.
Encyclopeadias have made claims at times that are unfactual, but they don't like uncertainties, so they come out with a definite one way (or the other).
There are far too many variables involved to carry out any meaningful experiments to prove or disprove this hypothesis.
Water will go down my plug hole one way or the other and I have no of controlling that, without some form of physical intervention.
Driver T

riaz4918

i dont know, let me go and ask it

alwaysbombed

The South pole is oriented opposite the North pole.

Gravitational pull is what makes the water swirl down the drain.

Because the South pole is oriented OPPOSITE to the North pole... is the reason why it goes down counterclockwise.

Zap

All water goes down the drain "counter-clockwise" south of the equator.

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