A Myth Down the Drain

Ecuador sounds similar to Equator for a very good reason. Here in Quito, we are 0°11’40” (read: just barely) south of this midway point between Earth’s poles. Heading to Otavalo this weekend for a trip to their massive Saturday market brought us (briefly) back into the more familiar, northern half of the globe.

For our own “crossing the line” ceremony, I opted to demonstrate my impressive knowledge of physics by showing the kids how toilets drained by spinning in different directions based on the hemisphere we were in (naturally).

The experiment cost us 15 cents, which was the price to use a public bathroom in Otavalo. (Should have heard me try to explain in Spanish we all didn’t need to go, but instead were doing science.) As expected, the toilet drained in a clockwise direction just like back in Vermont.

Arriving back in Quito later that afternoon, we conducted the second phase of our experiment. Flush! The draining water spun in exactly the same clockwise rotation. (Like many college chemistry labs in my past, I must have simply made some mistake.) Flush again! To my dismay, the results were again consistent with the first. The kids lost interest. I flushed one last time. Another clockwise rotation!

As it turns out, the Coriolis effect due to the Earth’s rotation does have an effect at the macro scale on things like hurricanes and cyclones, but household plumbing is a different story. Localized factors like the shape of the drain and how the water is moving to start are apparently far more important to determining rotational direction.

I guess Quito isn’t that different from home after all.