No, your Sink doesn't Drain Clockwise based on Hemisphere

This is a myth in need of busting. The erroneous bit of folk wisdom says that water always drains in a clockwise direction in the Southern Hemisphere, and in a counterclockwise direction in the Northern Hemisphere. The explanation is the fabled Coriolis effect. The Coriolis effect explains why big things such as hurricanes rotate in a clockwise direction in the Southern Hemisphere and counterclockwise in the Northern Hemisphere. However, when you get down to small phenomena such as the water draining out of your bathtub, the Coriolis effect is insignificant.

This was demonstrated in 1962 by Ascher Shapiro, a researcher at the Massachusetts Institute of Technology. Shapiro filled a circular tank six feet in diameter and six inches high in such a way that the water swirled in a clockwise direction. (The Coriolis forces in the Northern Hemisphere act in a counterclockwise direction.) Shapiro covered the tank with a plastic sheet, kept the temperature constant, and waited for two hours hours. When he pulled the plug, the water went down the drain clockwise, presumably because it still retained some clockwise motion from filling.

On the other hand, if Shapiro pulled the plug after waiting a full 24 hours, the draining water spiraled counterclockwise, indicating that the motion from filling had subsided enough for the Coriolis effect to take over. When the plug was pulled after four to five hours, the water started draining clockwise, then gradually slowed down and finally started swirling in the opposite direction. Needless to say, most people do not wait 24 hours (or even 4-5 hours) to drain a sink. Hence the influence of the Coriolis effect may be safely described as slight to insignificant.