Tuesday, February 21, 2012

Save Water at the Westin Hotel!

The sign in the hotel bathroom said, “One of your Heavenly® Shower heads has been turned off in an effort to minimize water usage and protect one of our most precious natural resources.”

I was curious whether this was true. Does turning off one showerhead really save water? My theory was that it depended on the plumbing. If the flow was limited by the showerheads, then the answer was yes. But if instead, the bottleneck was in the water pipe, upstream from the split, then no, the number of showerheads in use would not make any difference.
I am not the first to have contemplated this mystery of life. In 2010, Chad Orzel, Assistant Professor of Physics and Astronomy at Union College, Schenectady, NY, wrote an article, The Faulty Fluid Dynamics of Hotel Environmentalism, for his Uncertain Principles blog. Using a fairly sophisticated argument (there was math), Prof. Orzel concluded, “So, at best the ‘shut off one showerhead’ strategy might be saving 15% of the water usage…the real savings is probably considerably less, and consistent with zero, as a simple analysis of the plumbing would suggest.”

Being of a scientific nature, I ran an experiment of my own. First I took a long shower (using both showerheads) and got dressed. Then I went to the nearby CVS to buy a ruler. When I returned to my hotel room, I closed the bathtub drain and turned on the water. After the water had run from both showerheads for five minutes, I measured the water level in the tub. Four and three-quarter inches. Next, I drained the tub, re-closed the drain, and repeated the experiment with one showerhead. This time there were only two and three-quarter inches of water in the tub.

Findings: My results are inconsistent with Prof. Orzel’s. After accounting for the slope of the tub floor, I conclude that turning off one showerhead saves just about half the precious natural resources.

Good to know. I wouldn’t want to waste water.

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1 comment:

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