The parts are considerably better than the whole in this disjointed work on water (``the blood of land'') in North America. Trained as an environmental engineer, Outwater is at home with the technical minutiae of such matters as water treatment and sewage handling, about which she writes with surprising vigor. As a collection of oddments on the human manipulation of water, her book has many virtues: You will learn, for instance, that Poughkeepsie, N.Y., was the first American town to develop a filtered water supply; you will also learn in great detail how ``raw sludge brew'' is separated, how methane from sewage is converted to a source of power, and how aqueducts work. Outwater is also good at describing some of the basic matters of river ecology, noting the importance to the food chain of free-flowing rivers that support high levels of nutrients, and she makes a good case for restoring beavers and prairie dogs to public lands as agents to increase the production of wetlands, a crucial element of the ecosystem largely reclaimed over the past two centuries for agricultural and municipal uses. But Outwater is less successful at weaving the complexities of human affairs into larger questions of nature and the environment. She relies too often on undigested facts rather than carefully interpreted information. What is missing from this book is an appreciation for water both as a natural element--there is precious little in these pages about the chemistry of water or on how rain happens to form and fall--and as a defining force in human history. The focus is much narrower than the broad title and subtitle suggest, and readers will have to look elsewhere for a thorough natural history of water.