The present study was aimed at adding a piece of empirically derived information to the small amount of existing knowledge in the field of clinically inconspicuous drinking behavior. The central question that guided its conception was: How can the obvious interindividual differences in the volume of mineral water intake, which can be observed between ordinary people in their natural environments every day, be explained by drawing upon available psychological theories, models, concepts, instruments, and methods? The objective was to check up on the usefulness of a number of person-related and situation-related determinants that could be expected on theoretical grounds to have some potential for contributing to the analysis of these differences. Moreover, four models of food choice were tested, among them was the theory of planned behavior (TPB).