I recently read an article which confirmed my long-time suspicion that
there is no relationship between the direction the water goes down the
drain and which hemisphere of the world you are in.

Years ago, I saw a documentary about toilets being made (yes, I was
bored) and the toilet manufacturer was asked about the direction of
rotation of the water in the bowl.  It turns out that the direction
water goes down your toilet is determined by the angle of the holes up
underneath the rim of the toilet.  They angle those holes to make sure
that the water swirls around nicely instead of just shooting straight
down the drain.

By my own observations, I've seen water go down my sink, tub, and
shower drains in different directions.  By starting the 'whirlpool'
with my own hand, I can get it to go in whichever direction I want.

"Coriolis Effect" is the name of the effect to which people attribute
water's draining rotation.  It is a real thing, but on our relatively
slowly-spinning, large planet, it only really affects clouds and ocean
currents.  This was confirmed in a recent issue of "Popular Science",
where they debunked a bunch of popular myths.

I think the "carousel" vs. "merry-go-round" terminology issue is the
same as the "Pop" vs. "Coke", "Fridge" vs. "Icebox", and "Nightcrawler"
vs. "Dew-worm" issues, among many others.

Bill Mackin