A 2013 study released by the United States Geological Survey found that the chemicals we're putting in our yards are now in every stream, river, and lake, and half of our well water—all the sources of our drinking water. But what, exactly, are these chemicals, and what do they do to us? And how do they get from our yards to our taps? In The Great Healthy Yard Project, physician Diane Lewis describes in cogent, nuanced terms how we are polluting our drinking water and how it's putting our children's future at risk—and she offers a surprisingly easy way to chart a happier, healthier course forward, starting with changing the way we steward our yards.