Does water go down drains clockwise and counter-clockwise in different hemispheres?

This question was recently posted in one of the forums.the answer given was:

False. The Coriolis Effect is not strong enough to change the flow of a drain. It's determined by other factors like the placement of the drain and slope to the drain.

I remember a few years ago reading about a university that was trying to demonstrate the effect. The effect is there, but its forces are so weak that they are hidden by the far bigger forces produced by any irregularities in the shape of the plumbing, any slight slope of the waste exit from the bath and the way that the plug is removed.

The university experiments involved waiting a long time to ensure that any movements within the water had ceased and there were no temperature differences causing thermal currents. Given all the trouble they had I think it is very unlikely to be observed in out baths or toilet pans.

No it does not. This is a myth when talking about toilets and sinks.

Direction, speed, and motion that water will "go down" depends much more strongly on other factors.

This is a popular myth that is based on the Coriolis effect. Basically, it really depends on how the drain is set in your tub.

The erroneous bit of folk wisdom you refer to says that water always drains in a clockwise direction in the Southern Hemisphere, and in a counterclockwise direction in the Northern Hemisphere. The supposed reason for this "fact" is the Coriolis effect, which has to do with the effect of the earth's rotation on moving objects.

Well, there is such a thing as the Coriolis effect. It explains why macroevents such as hurricanes rotate in a clockwise direction in the Southern Hemisphere and counterclockwise in the Northern Hemisphere. However, when you get down to itty-bitty phenomena such as the water draining out of your bathtub, the Coriolis effect is insignificant, amounting to roughly three ten-millionths of the force of gravity (in Boston, at least, which is where they happened to do the measuring).

The boring truth is that water drains every which way no matter what hemisphere you're in, for reasons which have to do mostly with the shape of the drain, the way you poured in the water in the first place, and so on."

http://www.straightdope.com/columns/read/149/do-bathtubs-drain-counterclockwise-in-the-northern-hemisphere

You know the legend: In the northern hemisphere, water goes down the toilet clockwise. And it twirls counterclockwise in the southern hemisphere. It's a cool factoid, in itself. And it has a cool name -- the Coriolis Force.

[discovery.com/area/skinnyon/skinnyon970523/skinny1.html, no longer online]

The primary influence on how water goes down the plughole is how it was filled, how the water moved since and how it was disturbed when the plug was pulled. Water can swirl either way anywhere and the whole Northern/Southern Hemisphere idea is a myth. So the answer to the question is: it swirls the same way as it would anywhere else (but around a different axis of course!).

The Coriolis effect is what causes phenomena such as hurricanes to swirl clockwise in the Southern hemisphere and counterclockwise in the Northern hemisphere. With respect to a drain, the Coriolis effect is very slight, and as gmack said, water will drain in any direction depending on how the basin was filled, the shape of the drain, etc.

However, if the basin is allowed to sit for more than several hours, the Coriolis effect will start to... take effect. A study conducted in 1962 indicated that if a basin were filled and covered and let sit for 24 hours or more, the Coriolis effect almost certainly would effect the draining of the basin.

Most people, I would hope, would not leave their bathtub sitting for over a day.

As to the original question, even if the Coriolis effect is in effect, the fact is there is no real equator. What I mean is, there is no space where you are neither in the northern nor southern hemisphere. It would be highly unlikely that the drain be placed with exactly half in the northern and half in the southern hemispheres, and the balance of one over the other would effect the way the water drained.

https://en.wikipedia.org/wiki/Coriolis_effect#Draining_in_bathtubs_and_toilets

If I had a dollar for every time...

http://math.ucr.edu/home/baez/physics/General/bathtub.html

The coriolis effect, the equator moves faster than other latitudes. Imagine firing an artillery shell north from the southern hemisphere, in relation to the earths surface it would appear to deflect to the left. The opposite when firing south from the northern hemisphere.

I heard in the book of 'imponderables' that the spin in a toilet is caused by the jets of water and has nothing to do with the coriolis effect.

It's a myth.

http://www.snopes.com/science/coriolis.htm

I don't think that toilets flush in a particular direction based on its location north or south of the equator... I think that the direction in which the water flows is a function of how the water is pumped into the bowl in the first place... and THAT can vary from toilet to toilet...

Haviong checked this out when I moved from Pennsylvania to Australia, I can assure you that it is a myth! The location of water jets is the determining factor. Also, the twisting of water down the plughole of a bathtub depends on how you move your feet when exiting the bath, not its geographical location. These bodies of water are much too small for the Coriolis effect to have any impact.

A popular misconception is that the Coriolis effect determines the direction in which bathtubs or toilets drain, and whether water always drains in one direction in the Northern Hemisphere, and in the other direction in the Southern Hemisphere.

This myth is perpetuated by the Simpsons episode, Bart Vs. Australia. In reality, the Coriolis effect is a few orders of magnitude smaller than other random influences on drain direction, such as the geometry of the sink, toilet, or tub; whether it is flat or tilted; and the direction in which water was initially added to it. Note that toilets typically are designed to only flush in one rotation, by having the flush water enter at an angle.

This is less of a puzzle once one remembers that the earth revolves once per day but that a bathtub takes only minutes 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).

https://en.wikipedia.org/wiki/Coriolis_effect#Draining_bathtubs.2Ftoilets

It doesn't. It all depends upon how the water was introduced and the geometric structure of the drain.

One can find both counterclockwise and clockwise flowing drains in both hemispheres. Some people would like you to believe that the Coriolis force affects the flow of water down the drain in sinks, bathtubs, or toilet bowls. Don’t believe them! The Coriolis force is simply too weak to affect such small bodies of water.

In his work “Sur les equations du movements relative des systems des corps” (1835) the French engineer Gaspard Gustav de Coriolis (1792-1843) first described this force. The Coriolis force is caused by the earth’s rotation. It responsible for air being pulled to the right (counterclockwise) in the Northern Hemisphere and to the left (clockwise) in the Southern Hemisphere.

The Coriolis Effect is the observed curved path of moving objects relative to the surface of the Earth. Hurricanes are good examples. They curve to the right in the northern hemisphere and to the left in the southern hemisphere. What makes the hurricanes move in this way is the Coriolis force.

What happens at the equator? The Coriolis force is too weak to operate on the moving air at the equator. This means that weather phenomena such as hurricanes are not observed at the equator, although they have been observed at 5 degrees above the equator. In fact, the Coriolis force pulls hurricanes away from the equator."

http://www.loc.gov/rr/scitech/mysteries/coriolis.html