U.S. used less water in 2005 than in 1975, despite 30% more population

The United States is using less water now than during the peak years of 1975 and 1980, despite a 30 percent population increase during the same time period, according to a new U.S. Geological Survey report.

According to the report, Americans used 410 billion gallons per day in 2005, slightly less than in 2000. But it’s not all because we’re taking shorter showers: that number is the result of several factors, including public supply (water towers), domestic use (showers, faucets), irrigation, livestock, aquaculture, industrial use, mining, and thermoelectric power generation.

In fact, the 2005 numbers break down like this, according to the study:

• Public supply: 11 percent
• Domestic use: 1 percent
• Irrigation: 31 percent
• Livestock: less than 1 percent
• Aquaculture: 2 percent
• Industrial use: 4 percent
• Mining: 1 percent
• Thermoelectric power generation: 49 percent

As you can see, the lion’s share of water use comes from two places: irrigation and power generation. As such, the study attributes the decline since the 1970s to the increased use of more efficient irrigation systems and alternative technologies at power plants.

Meanwhile, water withdrawals for the public supply — water towers, etc. — have increased steadily since 1950 along with increases in population, which depends on those supplies.

In other words: though public-supply withdrawals have continued to increase overall, per capita use has decreased in many states since the 1970s.

Not surprisingly, the states with the most power generation and irrigation applications used the most fresh surface water: California, Texas, Idaho and Illinois. Similarly, the states with the most irrigation used the most fresh groundwater: California, Texas, Nebraska, Arkansas and Idaho.

Thankfully, the average amount of water withdrawn to produce a kilowatt-hour of electricity in the U.S. has decreased steadily from 1950 to 2005, owing to an increase in the number of power plants using alternatives to wasteful once-through cooling, which passes water through coolers a single time before discarding.