Drains reduce seepage uplift pressures, control seepage, and reduce foundation driving forces on dams and other structures, improving their stability. But many mechanisms plug drains, hampering their effectiveness. This manual provides information that can be used to establish an effective program to keep drains open. This manual also addresses the basic background, design, and analysis of drains. It aims to heighten awareness of the importance and benefits of drainage systems and the need for their periodic monitoring and maintenance.