Projected increased demand for food in developing countries over the next 30 years implies a correspondingly great need for additional agricultural water unless integrated research and development can achieve much higher water-use efficiencies. Without appropriate innovations in water management, poor access, quality and supply will continue to constrain food production. A global consortium recently completed the Comprehensive Assessment of Water Management and Agriculture (CA 2007) and identified many options for overcoming water-related constraints to sustainable food production in developing countries. Historically, research and development of water resources has neglected the potential benefits and impacts of livestock. Apart from drinking water, livestock professionals have not given adequate attention to the use of and impact of domestic animals on water and related environmental health. In the absence of good science, popular literature is often highly critical of livestock production because of its perceived excess depletion of vital water resources. The CA uniquely attempted to address this issue (Peden 2007). This paper summarizes the CA’s findings about livestock for the benefit of the British Society of Animal Science (BSAS) and the wider livestock research community.