OK, so the Coriolis Force has nothing to do with the way the water drains out of a bathtub - as the BA clearly describes in Chapter 2 (Flushed with Embarrassment) of his book. It's just a myth. So if you fill, say, a dozen different bathtubs and pull the plugs on them, some will drain clockwise and some counterclockwise. Right?
Why is it then that on every occasion I have tested this hypothesis the water always drains counterclockwise?
Is it possible that there's some truth to the myth after all, only it's not the Coriolis Force that is to blame, but something else? Like magnetism.
Water is a polar compound, so the water in your bathtub has a lot of ions in it - positively charged hydrogen ions (protons) and negatively charged hydroxyl ions (OH). Presumably as these drain out of the tub they are deflected by the Earth's magnetic field - pretty much the way air molecules in depressions and anticyclones are deflected by the Coriolis Force. Could this affect the way the water drains?