Safe drinking water remains inaccessible to many humans in the developing countries. Research continuously innovates to develop efficient and cheap methods to sustain clean water for developing countries. Developing nations are a broad term that includes countries that are less industrialised and have lower per capita income levels than developed countries. This chapter will discuss clean water for drinking water purposes. Pollution concerns of water in developing countries will be categorised in terms of physical, chemical and biological pollutants such as turbidity, organic matter and bacteria. Natural and anthropogenic pollution concerns linking with seasonal factors will be outlined. The multi-barrier approach to drinking water treatment will be discussed. Abstraction points used will be researched. Water treatment systems, medium-to small-scale approaches, will be discussed. The processes involved in removing the contaminants including physical processes such as sedimentation, filtration such as slow-sand filtration, coagulation and flocculation, and disinfectant processes such as chlorination will be reviewed. Other important methods including solar disinfection, hybrid filtration methods and arsenic removal technologies using innovative solid phase materials will be included in this chapter. Rainwater harvesting technologies are reviewed. Safe storage options for treated water are outlined. Challenges of water treatment in rural and urban areas will be outlined.