Over the next decades, growing populations will both put greater strains on available water and, in conjunction with changing diets, demand greater production of food. At the same time, climate change is likely to affect both water availability and crop water demand. Agriculture already consumes more water than any other human activity, and to meet the duel challenge of increasing food production and water sustainability, that water must be used efficiently. By assessing the range of variability in crop water productivity, measured in kilocalories produced per liter of water consumed, I identify regions of disproportionate water use and quantify the potential impact of improved on-farm management. Using an ecosystem services framework, it is then possible to assess the relative value of water regulation by a landscape.