There is an Urban Legend
about water, drains and Australia
. It goes something like this:
Because of the coriolis effect, which is due to the spin of the earth, water drains in opposite directions on either side of the equator.
This sounds pretty neat, and the coriolis effect is real, but it's not the whole story.
The problem is that the effort to isolate the coriolis effect is painstaking. In a kitchen sink, the scale of the coriolis force is incredibly tiny. Even the slightest disturbance can negate it, and small currents can persist for many days even in seemingly still water.
You don't have to travel across the equator
to test this, either. Simply fill a sink with water, wait until it looks still and then lightly paddle the water in one direction. Leave the water as long as you like. Open drain. Observe direction of water flow. Fill again. Paddle in the opposite direction. Let water settle as long as you want. Open drain. Repeat.