Water and agriculture are inextricably linked. Within Africa, several water-related challenges exist that present numerous obstacles and have the potential to impede Africa’s continued economic growth. These include: the threat of climate change, as characterized by extreme weather events such as floods, and frequent and intense droughts; a multiplicity of trans-boundary water resources without a coherent arrangement on riparian rights; lack of sufficient water infrastructure for supply and delivery of the water resource; and lack of official data on water use that can be used to formulate good public policy. All these factors have served to increase water scarcity and to raise the competition for scarce water resources between the agricultural sector and other sectors of the economy, such as industry and urban households. A prerequisite to mitigating these challenges is the establishment of an integrated water management system that promotes water productivity and efficiency. Thus, the primary objective of this study is to highlight methods and techniques for evaluating agricultural water productivity and water use efficiency that are replicable, globally. For this purpose we construct a total factor productivity index using the General index proposed in O’Donnell (2016), thereafter we demonstrate how to decompose the partial productivity of water using U.S. agricultural data for the period 1960-2004.