Why water sinks in antyclock wise direction in northen hemispear?

It is a thing called the Coriolis effect. The Coriolis effect is an observed reversal in spin of "things" like water, storm systems, etc. (Toilets in the Northern Hemisphere spin in the opposite direction of those in the Southern) To better understand this effect, observe global weather patterns. High and Low pressure systems in the Northern hemisphere spin Clockwise and Counterclockwise, respectively. It is the opposite in the Southern Hemisphere, because of Earth's direction of rotation. This is the Coriolis Effect.