Greywater management in low and middle -income countries : review of different treatment systems for households or neighbourhoods

This report provides a comprehensive description of the main components for successful greywater management and compiles international experience in greywater management on household and neighbourhood level in low and middle-income countries.
In urban areas of low and middle-income countries, greywater is commonly discharged untreated into drainage channels, on open fields or into natural aquatic systems. The rural and peri-urban areas mainly use untreated greywater for agricultural purposes, thereby leading to environmental degradation and exposing the population to health risks. Greywater is generally less polluted than domestic or industrial wastewater, but it may still contain high levels of pathogenic micro-organisms, suspended solids and substances such as oil, fat, soap, detergents and other household chemicals. Recommendations are formulated for control measures at the source, design of primary and secondary treatment systems as well as for safe reuse and disposal of treated greywater. The documented systems, which vary significantly in terms of complexity, performance and costs, range from simple systems for single-house applications (e.g. local infiltration or garden irrigation) to rather complex treatment trains for neighbourhoods (e.g. series of vertical and horizontal-flow planted soil filters). Treated greywater is not always reused. In regions with water scarcity and poor water supply services, emphasis is placed on agricultural reuse of treated greywater, whereas in regions with abundant water, greywater is of minor importance and locally infiltrated or discharged into nearby water streams.
With elaborated case studies from Mali, South Africa, Costa Rica, Nepal, Jordan, Palestine, Malaysia and Sri Lanka.