Water treatment plants, which are important installations holding a mission of public health, activate nevertheless important reactions of the inhabitants, disturbed most of the time by the olfactory annoyance. In addition to the phenomena of harmful effects (odors, noise, visual and fear of medical risks), water purification and energy or agricultural recovering refer to values of sustainability. The concept of sustainability implies a long-term projective concern which is often in contradiction with individual interests. In this respect, annoyances linked to waste purification plants question the dilemma between collective benefit and local individual interest refering to the NIMBY effect (Not in My Back Yard), when inhabitants exposed to industrial annoyances tend to disregard advantages, and consequently also the benefits of industrial installations for one’s environment, pointing only at the inconveniences that they experience in everyday life. This study was impelled by a public organization, whose request consists in obtaining applicable tools and recommendations to deal with potential oppositions of residents and to facilitate environmental integration of three water treatment plants in the suburbs of Paris. The three sites of investigation present a specific problematic: a first water treatment plant is going to be enlarged, the second one has projects to double its treatment’s capacities, and the third one doesn’t exist yet. Environmental psychology showed that the process of evaluation refers to a complex field of attitudes, representations and evaluations not only related to the harmful effects. Expressions of discomfort are to be put in perspective with the relation of the individual with his environment, of which the accused harmful effect forms an integral part (Moser, 2003). First, one cannot understand residents’ reactions without apprehending the representation of the source identified like polluting. Moreover, beyond the objective conditions of perception, beyond the supposed or real embarrassment caused by the presence of the source, it is important to include how the harmful effect is lived in everyday life and the threat that it represents for residents’ quality of life. It is important to observe the relation maintained with the harmful object, through the variable of implication, defined from the following dimensions: the degree of personal identification relative to the object (feeling to be concerned or not by the problem), the value system attributed to the object (values concerned, environmental and human consequences involved for example) and the perceived possibility of action (feeling to be able to control or not the harmful effect) (Rouquette, 2003). More one is implied, more one will need to solve the tension generated by the exposure to the harmful effect. Behavioural and cognitive strategies aim to reduce this tension and the restitution of a satisfying level of congruence, modifying for example the initial judgements on the object. Presence of harmful effects can generate stress and give way to emotive reactions which could lead to behavioural or cognitive, passive or active adaptation (Moser, 1995), based on forms of individual or collective control. The construction or the expansion of a structure has psychological, social and environmental impacts. It is the analysis of the interactions between these three aspects, which can provide answers adapted to each situation. Indeed, as Pol. (2003) declares: the immediate objectives, the strategies and the orientation of the actions have to be specific to places. Each site presents specificities that need different solutions. The communication will consist in introducing the methodologies adapted to specificities of the sites and problematic. It will be presented a model gathering the whole factors, which can have an influence on the environmental assessment and individual reactions. More particularly, we propose: 1 - to recount the requirements for quality of life ; 2 - to highlight representations of water treatment and the of the factory ; 3 - to measure the degree of implication with the harmful source ; 4 - to identify the cognitive and behavioral strategies to face the harmful effects. The data analysis will aim to develop a model aiming at apprehending phenomenon NIMBY. Furthermore, it will take into account personal variables that have been identified in the literature as having an impact on the process of environmental assessment, as well as physical measurements recorded in situ.Moser G. 1995. Stress, réactions cognitives et comportementales : Une analyse en termes de psychologie sociale. Thérapie comportementale et cognitive, 5, 3, 69-75.Moser G. 2003. Pollution atmosphérique et atteinte; la qualité de vie. Priméqual: Ministere de l’écologie et du développement durable, février 2003.Pol E. 2003. De l’intervention; la gestion environnementale; méthodologies et développement pour une psychologie du développement durable, in : Moser G. et K. Weiss, Espaces de vie, Aspects de la relation homme-environnement. Paris : A. Colin, p. 307-331.Rouquette M.L. 2003. dans : Flamand C. & Rouquette M.L. Anatomie des idées ordinaires : Comment étudier les représentations sociales. Paris : A. Colin.