Life Cycle Assessment (LCA), although widely disseminated in the industrial sector, remains underutilized in the public sector. The literature has addressed the relationship between scientific knowledge and decision-making from positivist and relativist epistemological perspectives. Both provide explanations for this weak dissemination and suggest solutions. Several of these solutions were explored through the implementation of a simplified LCA calculator in the public wastewater sector in France. This experiment highlighted the importance of two simplification principles: the first is to provide a calculator that already includes a catalogue of LCA ready-for use; the second is to guide the interpretation of LCA results by reducing, step by step, the number of impacts considered. A special effort has been made on the graphic format used to presents results. These principles can be generalized to other contexts. This work calls for the involvement of management sciences in LCA research and for co-building solutions with potential users.