It takes the same amount of water required by a city of 5 million to fuel a typical U.S. nuclear power plant for one hour: 30 million gallons, Fast Company reports. Charles Fishman, author of the book The Big Thirst, notes that "the U.S. has 104 nuclear power plants--more than any other country, a quarter of all plants worldwide." As the world's largest energy consumer, "49% of the water used in the U.S. goes to generate electricity," Fishman notes. That's "the single largest use of water" in the country.