Many Nepalese rural communities are suffering from lack of safe drinking water. One of the reasons is that approximately one third to one half of all drinking water supply systems fail shortly after the construction. The main purpose of this thesis project was to analyze the environmental sustainability of rural water supply systems implemented by the Rural Water Supply and Sanitation Project in Western Nepal(RWSSP-WN).In addition, the thesis project In addition, the thesis project also assessed the sustainability of the District Water Supply and Sanitation(DWSS) schemes from the institutional and financial point of view focusing on the organization and management capacity of the Water Users’ and Sanitation Committees (WUSCs) in managing their schemes including their Operation and Maintenance (O&M) management capacity to ensure the proper functionality and sustainability.

This thesis is intended to fulfill the requirement for the partial compliance of Bachelor’s in Environmental Engineering Degree Program at Helsinki Metropolia University of Applied Sciences, Finland. The thesis focuses primarily on the assignments carried out in the field, major observations noted, and interviews and discussions held with WUSCs and users/beneficiaries of each scheme visited. The data gathered during observations, discussions and interviews highlight the strength or major achievements of the schemes as well as the areas for improvement needed for the sustainability of the schemes.

Results show that most of the schemes studied have been affected by several water contaminants, mostly by E-coli, and some schemes also suffered from lime which caused a decrease in the sustainability of the schemes. Hence, it was concluded that to increase the sustainability of the schemes, the best available technology should be adopted to remove these water contaminants.

For this purpose, a study on best available technology to inactivate E-coli and remove lime, made, and several options were proposed to the RWSSP-WN project.