Book excerpt: Practical Drainage is easy to read and presented in a non-technical style generously supported with helpful illustrations. There are three key messages in this book: water moves sideways only slowly through soil--leading to a detailed description of how drains work; the how-and-why of perched water table methods of construction; and sands are different from one another--they must be tested before use in turf root zones. These key messages are preceded by detailed descriptions of how water moves into soils and the effects of compaction on that movement. The final chapters give step-by-step guidelines for calculating drain spacings and depths, based on measurements of the hydraulic conductivity of the soil and its various layers. There are also chapters about how to measure hydraulic conductivity and how to design and install sub-soil drainage systems.