As others have pointed out, the coriolois effect has nothing to do with magnetism.
But, further, the direction your toilet, sink, or bathtub drains has NOTHING to do with Coriolois or the location of your toilet in either hemisphere; for something that small Coriolois simply doesn't matter.
The direction it drains depends on on the shape of the container (and it can be controlled by VERY subtle changes in shape) or any lingering currents from when the toilet or sink or whatever is filled. It's largely random.
Sharpies take advantage of idiot tourists in equatorial countries by taking them back and forth across the equator "demonstrating" containers draining in opposite directions on either side; they do this by manipulating the container.
I know, I was kidding. :)
What do you think I am, a DUmmy?