Our water infrastructure is older than our roads and power grid, with many pipes sitting in trenches dug by hand in the 1800s. In parts of the Northeast, up to 50 percent of our clean water leaks into the ground between the treatment center and the tap. Across the country, we lose an average of seven billion gallons of drinking water a day to leaks—and we have an 800,000-mile network of pipes that needs constant monitoring and repair. We also use far too much energy treating all our water, regardless of its end use, and piping it long distances. Besides fixing up the nation’s pipes, the future of water is cleaning only what we need.