This book reviews the consequences of improper disposal of greywater into the environment and the most appropriate treatment technologies for developing countries, focusing on the potential to reuse greywater as a production medium for biomass and bio-products. It also describes the quantities and qualitative characteristics, as well as the common practice of discharging greywater in developing countries, and highlights the associated health risks. Further, it compares the management of greywater in developed and developing countries and explores the advantages and disadvantages of various treatment technologies, discussing the reuse of greywater for irrigation purposes in arid and sub-arid countries, especially in the Middle East. The book shows the benefits of greywater and introduces low-cost technologies based on the available local facilities can be used to discharge, reuse, and recycle it.