It is often said that if everyone consciously reduced their shower times by three minutes than an enormous amount of water could be saved. This claim interested me and I decided to delve further into this assertion. Because the average US shower takes 8.2 minutes, according to the EPA, I’ve decided to compare the difference in water use between 8.2 minute showers and 5.2 minute showers (the US average reduced by three minutes)

According to Home Water Works, a project of the Alliance for Water Efficiency, the average US shower takes 8.2 minutes, uses 17.2 gallons and has a flow rate of 2.1 gallons per minute. Furthermore, as stated on the Atlantic’s website, the average American showers six times a week. This means that 5,366 gallons are used per year per person in the United States from eight minute showers:

\[6 \text{ times a week}\times 17.2\text{ gallons} = 103 \text{ gallons used weekly per person}\]

\[ 103 \text{ gallons}\times 52 \text{ weeks in a year} = 5366\text{ gallons used per year per person} \]

If everyone reduced their shower time by three minutes and showered for five minutes instead of eight than 3,407 gallons would be used per year per person in the United States:

\[2.1 \text{ gallons per minute} \times 5.2\text{ minutes} = 10.92\text{ gallons} \]

\[10.92 \text{ gallons} \times 6\text{ showers per day} = 65.52\text{ gallons weekly}\]

\[65.52\text{ gallons weekly} \times 52\text{ weeks in a year} = 3407\text{ gallons}\]

Therefore the decrease in water which would result from this nation wide three minute reduction is 37%:

\[3407 \text{ gallons in five minutes} / 5366\text{ gallons in eight minutes} = 63 percent\]

\[100\text{ percent} – 63\text{ percent} = 37\text{ percent}\]

Now this seems like a significant decrease in water usage, but just how significant in terms of the amount of total water in the world. To determine this, you have to look at the percentage of total water used for domestic use and the percent amount of domestic water used for showering. According to the class notes from the first unit, ten percent of the total worldwide amount of water is used for domestic purposes and seventeen percent of water used for domestic purposes is used for showering. Therefore showering accounts for only 1.7 % of total water used in the US (if you apply worldwide averages to US averages):

.1 used for domestic purposes x .17 domestic water used for showering = .017 or 1.7 percent

After multiplying 1.7 percent by the 37 percent reduction calculated earlier, you get an overall .63 percent reduction of water if every American reduced shower times by three minutes. This seems like a very small percent reduction in the scheme of things. However, when reading this percent reduction in terms of gallons of water, the effects of shower time reduction seem much larger.

As stated in my older posts, there are 320,000,000 people living in the United States.

\[320\text{ mil people}\times 5366\text{ gallons in 8 min} = 1700000000000\text{ gallons}\]

\[320\text{ mil people}\times3407\text{ gallons in 5 min} = 1,090,000,000,000\text{ gallons}\]

\[1700000000000\text{ gallons} – 1000000000\text{ gallons} = 610000000000\text{ gallons saved per year}\]

610,000,000,000 gallons of water saved is a huge impact, especially for such a small action as reducing showers by three minutes. Although I was initially skeptical about the claims that three minutes of shower reduction time could save a lot of water, I know realize that these claims are true. Simple changes are all it takes to make a difference in the lives of others.

Rachel Lynn CampbellYes shorter showers save water, but there are so many other ways we waste water around the house because of leaky pipes and faucets and sprinkler systems, not to mention a running toilet- all things we just consider to be no big deal, but it actually adds up too.

seb5741Post authorNo you are right I fixed it. Thanks. The real average is 8.2 minutes not 8

Shawn Alan ZiffThis is interesting and makes me consider taking shorter showers. I admit my 10-15 minute showers are part of the problem not the solution. I am curious about the first set of calculations though. You say that the average shower time is 8 minutes and the average flow rate of the shower is 2.1 gallons/minute. Then you use the number 17.2 gallons for the average daily shower water consumption. Wouldn’t that number come from (8 minutes)*(2.1 gallons/minute) = 16.8 gal? The idea is all the same and this may come off at nit-picky but I was just curious where the other number came from.