Shower or Bath?: Essential Answer

March/April 2011

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Q: Which uses less water, a shower or a bath? This has been an ongoing debate in my home.

Asked by Anonymous, Northridge, Calif.

To be completely honest, the shower vs. bath debate hasn't been on my mind for the past four years. Most dorms don't have bathtubs, and when they are present, you can't help but wonder if you'll actually come out of them any cleaner. But I do occasionally yearn for a long luxurious bath. You bring up the crucial question: can we justify a long soak in the tub?

Unfortunately, unless you're taking 20-minute showers—more on that later—baths just can't measure up in terms of water usage. According to the U.S. Environmental Protection Agency (EPA), a full bathtub requires about 70 gallons of water, while taking a five-minute shower uses 10 to 25 gallons. You might argue that very few people fill the tub to the top, but a simple calculation shows that either way, baths use more water. If you're still unconvinced, try stopping the drain during your next shower to measure the amount of water you use. Then compare that to the amount you use for a bath. Chances are, you'll find the same result: showers save water.

But let's not stop there. We can save even more water and money with another small adjustment: the low-flow showerhead. If every household installed one of these water-saving wonders, the United States could reduce its annual water consumption by 250 billion gallons, according to the EPA. This adds up to a $1.5 billion savings on water bills across the nation. Tack on the energy savings from heating less water and low-flow showerheads become extra appealing. Check out the EPA's WaterSense program to find out more, including where to find more efficient showerheads: those that use 2.0 gallons per minute or less instead of the standard 2.5 gallons per minute.

Worried that the lower flow will reduce the quality of your shower? Both the EPA's performance criteria and I can assure you this will not be the case. When Stanford switched to low-flow showerheads halfway through my freshman year, I hardly noticed the difference. When you do make the switch, any qualms you might have about lower water pressure or the cost of a new showerhead will soon be calmed the water, energy and money you'll save.

Honestly, going low-flow is a no-brainer. But here's one more incentive: By using a low-flow showerhead, you might even be able to justify a relaxing bath every once in a while. If you take a six-minute shower with a low-flow showerhead, you'll save at least three gallons of water each time you shower rather than take a bath. Let's assume that you fill up the tub about halfway when you bathe. Then every 12 showers you take saves enough water for one bath—about 36 gallons. If you only take one bath each month, you'll still be saving tons of water, so you can enjoy your reduced-guilt baths even more!

Tessaly Jen, '11, is an earth systems major.

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