List of common misconceptions
The Coriolis effect does not determine the direction that water rotates in a bathtub drain or a flushing toilet. The Coriolis effect caused by the Earth's daily rotation is too small to affect the direction of water in a typical bathtub drain. The effect becomes significant and noticeable only at large scales, such as in weather systems or oceanic currents. Other forces dominate the dynamics of water in drains. In addition, most toilets in the United States inject water into the bowl at an angle, causing a spin too fast to be significantly affected by the Coriolis effect.