To what extent will population growth, rising level of pollution and climate change intensify the water crisis? Exactly how much water is available per person in countries around the world? How much will we need for food security in the coming years? The international community has pledged to reduce by half the proportion of people without access to water supply and sanitation by 2015. What regions are on track? How much will it cost to achieve these goals? What is the likelihood that countries will go to war over water in the near future? These questions and others are addressed in this Report, which offers the most comprehensive assessment to date of the state of the world's freshwater resources, based on the collective input of 23 UN agencies and convention secretariats. The global picture is complemented by the presentation of seven pilot case studies of river basins representing different social, economic and environmental settings: Lake Titicaca (Bolivia, Peru); Senegal River; Seine-Normandy; Lake Peipsi/Chudskoe-Pskovskoe, (Estonia); Ruhuna Basins (Sri Lanka); Greater Tokyo; and Chao Phraya River (Thailand).