The Science of Sustainability

How To Wash That Energy Waste Right Out of Your Hair

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One morning I realized that I could cut down my showering time by at least one minute if I could combine my shampooing and conditioning into one step. I went to a grocery store looking for a combination shampoo and conditioner that really works. I’m still looking, but I know they are out there.

A study commissioned by the California Department of Water Resources looked at water use in California single-family homes. The study determined that showering was the third largest user of water inside a home, after toilets, which are the biggest users, and washing machines the second biggest.

There are about 36-million people in California. Each person uses about 18 gallons of water each day for a shower. I’m not including baths, but baths generally use as much as or more water than showers. The average shower lasts about 9 minutes. Average flow rate is about 2 gallons per minute. If just 10% of us switched to a combination shampoo and conditioner, shaving at least a minute off of our shower time, it would save the state:

1/9 minutes x 18 gpm x 365 days x 3.6 million people = 2,628,000,000 gallons of water each year

Anywhere from 50%–75% of the water in a shower—depending on the preference of the person taking the shower—comes from the water heater. To heat a gallon of water from 600F to 1050F takes about 375 Btu, which is the equivalent of 0.1 kWh. At a price of $0.12 per kWh, the cost of heating a gallon of water is about one cent. If half the water used in a minute of showering is heated water, and one out of ten of us switched to a combination shampoo and conditioner, the amount of energy we could save and the cost of that energy is about:

2.63-trillion gallons x 0.5 x 0.1 kWh = 130-million kWh of power saved each year

and

130-million kWh x $0.12 per kWh = $15.8-million saved each year

For an individual, switching to a two-in-one shampoo and conditioner could save more than 730 gallons of water a year and save about $4 in energy costs.

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Category: Environment, Water

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Jim Gunshinan

About the Author ()

Jim Gunshinan is the editor of Home Energy, the magazine of sustainable home building and renovation.
  • David

    Many shampoos say on the bottle, lather, rinse and repeat. The "repeat" part is only to sell more shampoo and is not really needed. How much in water and energy is this one word sham costing us?

  • Sarah

    Shampoo/conditioners are really harsh on hair. Good idea if your hair is naturally low-maintenance, but the rest of us should save water/our hair by using dry shampoo more often. Besides, washing hair everyday strips hair of its natural oils.

  • Chris

    Great article. I do feel obligated to point out that there were a few inaccuracies in your unit terms. In the first equation one can only assume that gpm is "gallons per min" in which case you would say 1min x 2gpm instead of 18gpm. Also in the second equation its 2.63billion gallons, not trillions.

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