This Manual provides information for designers, builders and operators about a wide range of applications and objectives such as developing, implementing and operating Artificially Constructed Wetlands (ACW) and Waste Stabilization Ponds (WSP)Standard systems approach which can be adopted universally and which can accommodate a development technology with changes in information concepts and ideas with timetheoretical background on the biological, chemical and physical processes of each method, the current state of the technology and technical knowledge on how to design, operate and maintain themand theoretical knowledge on how best the models may be used to describe the systems.