Dietary factors play a key role in the water use patterns of pigs. To avoid deprivation and related impaired performance due to individual or environmental factors, animals in commercial pig barns are usually given free access to water. Efforts to reduce water wastage have the potential to minimize the impact that large scale pig production units have on the supply of groundwater, a valuable natural resource. Manure produced by intensive hog farming contributes to operating costs related to the storing and hauling of slurry. A clear understanding of the relationship between diet composition and water intake therefore has practical implications for minimizing costs and addressing environmental concerns associated with large scale pork production.