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Shower vs. Bath, an Experiment

© Copyright 1996, Jim Loy

I have heard, more than once, that a person uses more water taking a shower than taking a bath. I was skeptical. So, I performed a simple experiment.

I took a shower, with the plug in place. I tried to make it a normal shower (humming and wondering if the phone was ringing), except for the fact that my feet would be more wrinkled than normal.

I found that I used much less water than I do when taking a bath. This is an experiment that I recommend. Don't believe those strange-but-true authoritative statements (like "No one knows why...") as fact.

Another such statement (concerning bathtubs) is that, in the Northern Hemisphere, the water that goes down the drain goes counterclockwise (or is it clockwise?). Bull. The Coriolis "force" does tend to make this happen. But, there are other forces going on, including the bends in the pipes leading to the faucet, and how you stirred the water, while sitting in and getting out of the tub. I suspect that the Coriolis effect is less important than other effects. I haven't performed this experiment.

Still another such statement (concerning showers) is that singing sounds better in the shower. People have speculated that the acoustics of the small shower stall are the cause. Well, I think it is the "white noise" of the shower, which softens the sound of your voice. Also, I think you actually hear the original record, in your mind, while you sing. That's why everyone likes to sing along to those nostalgic Beatles records, and make innocent bystanders cover their ears. This experiment is harder to perform, as I would have to statistically sample singers and listeners, both in and out of the shower (all permutations).

Comments: I have received a couple of email messages, saying that it is common knowledge that showers take more water than baths, water goes down the drain counterclockwise in the Northern Hemisphere, and singing in the shower sounds better because of the acoustics of the shower stall or whatever. I think that is what I said above. And, I still think that all three examples of common knowledge are wrong.

Apparently, I am well supported by scientists with the water going down the drain counterclockwise. Numerous books on astronomy agree with me there. The Coriolis "force" is very real, and very important to the weather. But it is much too weak to be measured in your bath tub. There was an article in Scientific American, reporting experiments, in the "Amateur Scientist" section, long ago, which also agreed with me about that.

Incidentally, I put quotes around "force," twice, when I said Coriolis "force." This is not a criticism of Mr. Coriolis or his "force." This is just my way of pointing out that it is not a real force, but is instead the result of the fact that our whole frame of reference is rotating. A flying object tends to fly straight. But, the earth is turning under this flying object. So, the object seems to be curving to the right, in the Northern Hemisphere.

And, the whole idea of the above article is to encourage you to check out that common knowledge, with your own experiments, when possible. You will sometimes make mistakes, and think you have proved things which are not really true (See A Magnetism Experiment). But, science is much more interesting when you get involved.

I have performed the above shower vs. bath experiment several times, and I normally use less than half a tub of water to shower. Of course other people may use more. But, I suspect that most people use much less than a tub of water. I imagine that the reason that people think a shower is so wasteful is that it looks wasteful. A lot of that water is not even touching me, or it is just concentrated on one clean portion of my back. Well, there is a huge amount of water in one tub. Perform my experiment, and see.

Addendum:

So, why would the Coriolis effect tend to make the water go down the drain counterclockwise (in the Northern Hemisphere), when the Coriolis effect actually tends to make moving objects curve to the right (clockwise)? On the left we have a drawing of the spinning earth. And we have wind or water moving toward a point, a low pressure area or my bathtub drain. The wind or water curves to the right, because of the Coriolis effect, and makes the little vortex in the middle turn counterclockwise. But, in my bathtub, the curving of the water due to the Coriolis effect is very tiny, compared to other forces.

In my first version of the above article, I got it backwards. I said that the water would tend to go clockwise, in the Northern Hemisphere.

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