The bottled water industry is a profitable and still growing business in Switzerland. However, sustainable and informed consumption should lead customer’s preferences to tap water: It is provided as a high (in some cases higher) quality product with a very low price. Moreover, tap water does not require transportation or bottling—hence it produces no waste and pollution. Thus, the apparent consumption behaviour is peculiar, and the question remains: Why do customers buy bottled water, while rational reasons might lead to the tap water alternative? It seems that psychological factors play an important role when a person decides to consume either alternative. The purpose of the present study is to investigate these factors with psychological impact. At a first glance, these factors may be divided into the following four groups: (1) personal factors, (2) social factors, (3) situational factors, and (4) demographical factors. Within these general factor groups, the study in particular focuses on concepts that may be subsumed as cognitive contradictions, because these psychological processes appear to lead to curious behaviour consequences. A first literature review showed eight such concepts: (1) anxiety/worry, (2) reactance, (3) dissonance, (4) loss of identity, (5) anger/compassion, (6) inferiority/jealousy, (7) shame, and (8) inequity. Each of the focused factors is described in a mode of action model and then—according to relevant literature—transformed into questions and items. Dependent variables are the customer’s satisfaction and the consumption of either of the alternatives as well as the application of in-house treatment methods and in-house treatment devices. The questionnaire is mailed to a representative sample of the German speaking Swiss population. The sample is drawn randomly from the telephone book, and in order to receive a high reply rate the respondents will be provided with reminders. After analysis, the results will show, which of the proposed factors and concepts influence the satisfaction, the consumption, and the application of water treatments and how this influence looks like.