The provision of water supply, sanitation and wastewater services generates substantial benefits for public health, the economy and the environment. Benefit-to-cost ratios can be as high as 7 to 1 for basic water and sanitation services in developing countries. Wastewater treatment interventions, for example, generate significant benefits for public health, the environment and for certain economic sectors such as fisheries, tourism and property markets. The full magnitude of the benefits of water services is seldom considered for a number of reasons, including the difficulty in quantifying important non-economic benefits such as non-use values, dignity, social status, cleanliness and overall well-being. Also, information about the benefits of water services is usually hidden in the technical literature, where it remains invisible to key decision-makers in ministries. This report draws together and summarises existing information on the benefits of water and sanitation.