In Vietnam, achieving sustainable provision of water services for communities in rural areas has been a challenge for years. About 74 percent of the Vietnamese population is concentrated in rural areas, yet just 48 percent of households have access to clean water, compared with 82 percent in urban areas. Only 30 percent of small towns have piped water systems, and even then the proportion of connected households can be as low as 20 percent. Many settlements have no water systems, and during the dry season residents have to rely on polluted sources for basic household needs. This paper reviews the successful implementation and subsequent scale-up of an Output-Based Aid (OBA) scheme to provide access to safe, clean water for low-income, rural households in central and southern Vietnam, through local communities and small private operators.