The evolution of the paradigm of urban water management highlights the issue of sustainability of water utilities. It appears that the social aspect of the sustainability is not enough considered even if its impact on global equilibrium is significant. The proposed study focuses on the concept of social sustainability that is analysed according to theoretical and empirical self-developed decision aiding model for water pricing mitigation called “modèle de tarification solidaire multi-objectifs, TSMO”. It aims at highlighting internal solidarity mechanisms able to ensure trade-off between budget equilibrium of the utility and equity between users and utility in order to share the financial effort in a robust and sustainable way. This goal can be reached by eliminating the poverty in water with the help of an adaptative pricing tool.