The Humanure Handbook, 4th Edition

This is a very good book and piece of propaganda. My complaint with most books of this style is that they are too repetitive, and despite there being a lot of repetition in this book, it manages to be thoroughly engaging nonetheless. Lots of excellent history and science.

It's hard to believe that before reading this it seemed completely normal to me that the United States uses billions of gallons of clean drinking water per day just to defecate in.