Davis Sedlak provides a comprehensive and entertaining history of fresh water treatment and delivery as well as a technical overview of the evolution of modern sewer systems and sewage treatment methods and facilities. Most of us in the industrialized world go through our day running the tap, flushing the toilet, and a dozen other water use activities, without giving a thought to where this cool, clear, life sustaining fluid comes from, how it gets to us, or how it is kept chemical and germ free. As it disappears down the drain and into sewer pipes we hardly wonder where our waste goes for treatment to remove pathogens, or where it might end up after that. We only become moderately curious (more likely outraged) when the tap runs dry or the sickly-sweet smell of sewage invades our homes and taints the breeze. Modern water treatment and delivery systems evolved from fairly small scale and simple (but effective) systems in Roman times to highly complex and sprawling networks that (in cases like California) pipe water to urban hubs from hundreds of miles away. In the largest world cities, millions of gallons flow through faucets every day while millions of gallons of sewage are processed and disposed of in the same time period. Sedlak explains the fits and starts by which we lurched from ancient 1.0 water systems to our, now outdated, 3.0 versions. The author explains the pitfalls of not upgrading to modern 4.0 systems, which he describes in detail toward the end of the book. He covers a range of water 4.0 features and methods, such as desalination, decentralized household treatment, toilet to tap solutions, and recycled non potable water conservation measures. Along with all this he also addresses the painful financial costs that new system upgrades can impose, especially if thought through poorly, executed or marketed incorrectly, or delayed for too long. After reading this book I won’t ever again watch a glass fill with water or listen to a toilet flush without thinking about the often crumbling infrastructure that supports our easy access to water, saving us time and keeping us safe from pathogens and poisons. At the end of the day the highway, bridge, power, and communications systems in this country get their due attention from politicians and the press, but arguably, the most important, water infrastructure, gets little consideration until there are massive failures that are difficult to come back from.