I watched a programme recently stating that the water does not go the opposite way down a plughole in Auz,?

Question

No body belives me when i explain, can anyone please put this to rest?

Answer 1

Its to do with the Coriolis effect, which has nothing to do with gravity but more with the rotation of the earth.

Here's an excerpt from Wikipedia:

Draining bathtubs/toilets

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 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 falacy is true[1].

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; most notably, the direction in which water was initially added to it and, secondarily, whether its basin is flat or tilted. Note that toilets typically are designed to only flush in one rotation, by having the toilet water shoot into the basin at an angle and via the force of a pump. If you shot water into the toilet basin from the oposite direction, you would obtain opposite results. That is 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 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).

Answer 2

This should clear this up once and for all. If the water swirls one way north of the equator and the other way south of the border, then what way does the water swirl right on the equator? The key here is that the water always goes DOWN, toward the center of the earth where gravity is doing its work. Gravity is too strong to be countered with other influences. As far as gravity is concerned, any point on the surface of the earth is a north or whatever pole you choose to call it.

Answer 3

Okay guys, like all things on earth this is to do with physics, the way the water goes down the plug hole depends on the last tap that was on at the time, if you have seperate taps for hot and cold water then the last tap that was on moves the water in a particular direction, then when you remove the plug even if the water seems still the water molecules are still moving in that direction, that is the direction the water then goes down the plug hole.
though obviously position of plug hole differs the effect as does if you have a combination, then it depends on the position the tap is in when the tap was on.

Answer 4

Water should flow the opposite way in the Southern Hemisphere. However it can be affected by local atmospheric conditions and the design of the basin.

This phenomena is exploited by entrepreneurs in Africa who will "demonstrate" the draining of water in opposite directions on both sides of the equator to interested tourists.

In reality the gravatational forces are too subtle to make any difference on the equator and the use of stick to stir the water is what is making the difference.

Answer 5

I have noticed that in the US your toilets are 3/4 full of water, our's only have a small amount at the bottom (we don't get splashed when doing a number 2). In the US the toilets seemed to just suck it straight down, no swirling. In Australia our pours water through to push it down, again no swirling. If you were to look when emptying a bath tub you may see it rotating.

Answer 6

This is a difficult one to answer, its been studied and I dont think anyone has got a definitive answer. Some say its according to position on the earth, some that it due to the plumbing/plughole..

Answer 7

I used to live in New Zealand and it DOES go the opposite way round. - To do with gravitational pull on the earth or something - everything south of the equator is the same.

Answer 8

In Argentina the water in the toilet goes down in the same direction as in the US.

Answer 9

It doesn't go down the opposite way, that's just one of those funny myths that everyone thinks is true.

Answer 10

Ok I am in Australia and the water goes down the right way here.
If yours doesn't you will just have to move here.
By the way its clockwise.