Measuring Embodied Blue Water in American Diets: An EIO Supply Chain Approach

Food systems worldwide rely on water resources that are facing demand from a growing population while regional water supplies are increasingly uncertain due to climate change. In this environment, dietary changes may have the potential to reduce water used in food production. At the same time, it is well established that American diets need to change in order to align with Federal healthy eating guidelines. In this article, we examine if there are synergies between healthier diets and blue water conservation in the U.S. food system. We estimate blue water use by supply chain stage using a multi-regional environmental input-output model. Then, we link this blue water to individual food items and use mathematical optimization to model healthy diet scenarios that meet the Dietary Guidelines for Americans. We find that while healthier U.S. diet outcomes and blue water conservation can be synergistic, these goals may also be competing. Making minimal changes from current American consumption to a healthy omnivore or vegetarian diet, blue water use increases by 16%, but the omnivore and vegetarian diets reduce embodied blue water by 63 and 66%, respectively, when the objective is to minimize water use.