This book describes the principles and construction plans of grey water treatment chains for the different treatment options. The main aim is to sensitizing and encouraging national, regional and municipal water and environmental sanitation authorities and agencies to integrate grey water management into their development policies and programmers. The book consists of five chapters. Chapter one includes general introduction about grey water definition, characterization, uses, and recycling. Chapter two summarizes the different grey water treatment methodologies. Chapter three presents case studies for the application of grey water treatment systems in some developing countries. Chapter four deals with the evaluation of different grey water treatment systems produced commercially worldwide based on an evaluation strategy according to specific ranking system. In chapter five, a description for a newly developed cost effective treatment system designed and executed by R&D TECH is shown. As an outcome form the work, we designed software to be used for cost analysis of the different grey water treatment systems and will be included with the book.