Why We Fight a Shower War

In an April 9 fact sheet, President Trump explained how he will “make showers great again.” Whereas his predecessors had sought green solutions through limited water use, he was reversing their initiatives. He said we should return to a water flow of more than 2.5 gallons per minute. In the past, because of government’s water efficiency rules, we used 12% less water. Since showers represent close to 20 percent of a household’s water use, we could be talking about a massive uptick.

Water Flow

Like Seinfeld, many of us were unhappy with the restricted shower head flow rule that began during 1992:

Actually, a good shower might not even need more water. Instead, according to U.K. research, it’s the shower head’s pressure that matters. After observing 86,421 showering events for 39 weeks, they concluded that more water pressure led to shorter showers:

But a timer also made a difference:

Water Stress

We care about our showers because of water stress.

Defined as the population’s demand for its local water, we say that water stress is high when people consume more than 40 percent of their renewable supply.

We can measure water stress by comparing freshwater withdrawals to internal renewable resources. Consequently, nations at the 25% level of withdrawal have no water stress. Ascending, at 25% to 50%, we see low stress, 50 to 75, medium, 75 to 100 high. Meanwhile, above 100 is a crisis level. The Washington Post tells us that currently 3.3 billion people are highly water stressed:

But maybe these maps say the most:

Our Bottom Line: The Diamond Water Paradox

Adam Smith wondered why water costs much less than diamonds. After all, we need water to survive while diamonds are merely an extravagant luxury. Years later, economists had the answer.

They just had to think at the margin, about the cost of the next extra unit.

With water, when there is a lot, the next extra glass, or flush, or shower costs little. Totally though, water is priceless. With diamonds, the opposite is true. We would rather have that one extra diamond and will pay a lot for it. And yet, the total usefulness of diamonds is small compared to water.

Economists here say that we are comparing marginal utility to total utility—the usefulness of the next extra unit that we consume to its total usefulness.

Returning to where we began, you can see that water’s marginal utility makes it very easy to increase our water flow.

My sources and more: President Trump’s showerhead executive order encouraged us to ponder how much water we use. From there, it made sense to check the economics here and here and here and In addition, this research provided insight. And finally, for much more on water stress, I recommend The Washington Post and this past econlife post.