Not entirely true. If the basin is perfectly symmetrical and the
water is allowed to dampen out all vortices from the filling process
(i.e. allowed to rest for a day or two) the Coriolis Effect does make
it drain counterclockwise. It works the same way all over the globe.

You'd be hard pressed to find any usual basin made by the hand of man
with perfection enough to achieve what you describe.

There have been some scientifically controlled experiments along these
lines to see if it worked - not so much because the effect of the
Coriolis motion was in doubt, but because they wanted to see if they
could design an experiment precisely enough to do the job. They did -
but yes, it took several days, and a bunch of money - more than the
value of your typical toilet or kitchen sink.

I still stand by my original statement. In small basins of imperfect
design, it makes no significant difference at all. Coriolis is
typically appreciable only on large scales where the local effect of
the earth's rotation *relative to the scale of the motion of the fluid
being acted upon* is large - like mesoscale (~100 miles in breadth) and
larger. It also helps that air is far less massive than water.
Oceanic currents respond far more to sea floor- and continental-shape
than coriolis.

Bruce Jensen