Psychological processes at the individual, interpersonal, group and collective level play a relevant role in affecting environmental “Global Changes” occurring in our biosphere (Pawlik, 1991; Levy-Leboyer et al., 1996). Among the various global changes related to human activities, one of the main priorities in the current environmental agenda (both for biophysical and human-social science) is represented by the human use and attitudes towards fresh water resources. Recently, some authors have proposed a measurement instrument labelled as NHIP (New Human Interdependence Paradigm), which is a new tool to measure pro-environmental attitudes (Corral- Verdugo et al., 2008). This scale is meant to cover the principles of Sustainable Development, and precisely the idea of an interdependence between human progress and environmental conservation. The results has shown that the NHIP scale explains an additional proportion of variance in a relevant ecological behaviour such as water conservation, also after controlling for the traditional NEP dimensions (Dunlap & Van Liere, 1978; Dunlap et al., 2000). Pro-environmental behaviours occur in specific places and thus, to predict them, is crucial to take into account spatial-temporal dimension of the psychological processes affecting them (Bonnes & Secchiaroli, 1992; Bonnes & Carrus, 2004). In this regard, some authors underline the importance to consider the placespecificity of psychological processes (Bonnes & Secchiaroli, 1992). When a common resource such as fresh water is limited, we are in a common dilemma situation. Common dilemmas are “social dilemmas in which non cooperation between individual people leads to the deterioration and possible collapse of a resource” (Kopelman, Weber, & Messick, 2002, p. 113). Within these situations, observing the behaviour of other people is a fundamental source for the formation of social norms and for taking individual decisions: in fact the behaviour of others in the spatial context proximal to the individual might activate and leading own behaviour (e.g., Carrus et al. 2008). This kind of norms can hamper the effects of common dilemmas because people will engage in water conservation only if they belief that also others do it. The study presented here has three main aims. First, we wanted to assess if different wa- ter availability could lead to different water saving behaviours. Second, we have hypothesized that beliefs about water saving behaviours performed by other people can affect individual water saving behaviour. Finally, the impact of the endorsement of the NHIP on water saving behaviour has been assessed. Participants in this study were 248 individuals recruited in two different cities of Italy (127 Ss in Rome and 121 Ss in Cagliari, Sardinia), differing for their water availability/scarcity: water availability being higher in Rome compared to Cagliari. Among others, the questionnaire investigated the different water uses during a typical day, the perception of quantity of water used by the respondent and by others and the environmental worldviews measured by the NHIP scale. The results show that citizens living in Cagliari, who have experimented water scarcity and periodic supply restrictions in the past more frequently compared to citizens living in Rome, engaged more in water saving actions in their daily lives. As expected, people engaged more in water conservation when they believed that others conserve it too. With respect to environmental worldviews, results show that beliefs about the interdependence between human progress and environmental conservation positively predict water conservation behaviour. The implications of these results are discussed.