The water utilities are supposed to take into account public interest and the environment. That's why they are a perfect example for studying the emergence of social performance within the firm-society relationship. Based on action-research, governance of delegated water services since 1945 has been analyzed through a neo-institutional framework. Institutions, actors and incentive tools are the three analytic dimensions chosen. We highlighted the dynamic link between performance, changes in reporting practices and governance reforms. It is shown how the use of non-financial reporting has developed in response to a performance definition more and more inclusive. At first voluntary and then becoming regulatory, reporting can help restore the trust amongst stakeholders and stabilize governance.