Water and electricity

Why don’t we think of water use as energy consumption?

“Hey, turn off that light, you are wasting water!”

“Turn off the hose, you are wasting electricity!”

Sound like nonsense? It isn’t.

When you use energy, you are also using water, lots of it. About 90 percent of the electricity generated in the US is generated by thermoelectric power plants—coal, nuclear, natural gas, and oil plants—that require cooling. These plants boil water for steam to turn turbines that generate electricity.  A 2010 US Geological Survey Report says 161 billion gallons of water are withdrawn in the States each day for energy production. Gasoline production also requires water.  Researches at Lawrence Berkeley National Laboratory estimate that the US uses over 1 billion gallons of water per day to refine nearly 800 million gallons of gasoline and other petroleum products. Take public transportation and you’re taking it easy on the water supply.

Lost in the metrics for electricity use–kilowatt hours, kbtus and CO2 emissions–are gallons. Switch to LED lights or install occupancy sensors and you’re saving water. The reverse is also true; turning off the faucet while brushing your teeth saves energy. The connection between water and energy is often lost because the savings are indirect – we don’t see the hard numbers on our utility bills.


We can even quantify this relationship between electricity and water. Approximately 4% of the electricity generated each day is used for water supply and treatment. This equates to 6,016,997,980 kWh per day to treat 42 billion gallons of water consumed. This equals about .1433 kWh/gallon. According to the EPA, the average American family of four uses 400 gallons of water per day. That equates to 57kWh of energy per day for us to shower, wash clothes, flush toilets, and cook. That’s roughly the same amount of energy used to run a 25 cu. ft. refrigerator for 15 days or a 55” LED TV for 325 hours. Maybe my daughter’s five-minute shower timer is not such a bad idea after all.

The link between energy and water is definitely interesting. It is often overlooked because the water use in generating electricity is hidden in our kWh charge, and the electricity usage in water treatment is hidden in our water rate charge. This water-energy nexus will need closer examination in light of droughts continue and increasing energy consumption. Some communities are already addressing this connection. Gresham, OR, Pima County, AZ, and Boulder, CO have installed a combined 2.423Mw of solar arrays to generate electricity to treat wastewater. The more we make the connection between water and energy, the more likely it is for us to see similar projects pop up across the country.

On the bright side, the next time you switch off that light, just think of the water you are saving.


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