Drownings, sometimes fatal, still occur in French Public Swimming Pools (PSP) in spite of the obligation of constant supervision by qualified lifeguards. We make the hypothesis that organizational aspects may affect the mission of pool supervision. Our study takes a systemic approach that views safety as an emergent property and drowning as a multifactorial and long-term process that is not restricted to the end of an accidental sequence. Method: We conducted a qualitative survey at four municipal PSP in France based on documentary analysis, participant observation, and 30 semi-structured interviews. Results: The findings revealed that several interrelated elements influence the detection by lifeguards of bathers in distress: 1) their training, their conception of the profession and the reasons that led them to enter this occupation; 2) their representations of the drowning risk and the evaluation of their ability to perceive such situations; 3) the question of regulation ; and 4) the methods of dealing with this framework in the concrete and daily operation, which involves trade-offs and appropriations at each level of the system. Conclusions: In order to identify the most significant influences, it seems relevant (1) to shift the focus away from these professionals; and (2) to prioritize an analysis of the functioning of the risk management system as a whole, not just critical or post-accident periods. In order to reduce the risk to swimmers, it seems preferable to identify the source of the constraints that weigh daily on lifeguards in charge of pool supervision. The functioning of PSP is the end result of joint regulation processes likely to influence, positively or negatively, the identified feedback loops. Our analysis highlights informal practices that turn out to be a compromise between several challenges (continuity of operation, the ability of pool lifeguards to sustain supervision over long periods, minimizing operating costs, preservation of the lifeguards’ autonomy, and preference for more appreciated missions). Both supervision and its intended aim – its capacity to detect aquatic distress – are of a rather random nature. This makes the level of safety variable due to a multitude of parameters, and does not offer users the same guarantee of safety. If accidents are relatively rare this is due to the coexistence within these facilities of relatively effective, but in fact poorly coordinated feedback loops. An analysis of the pool supervision in place can help to identify early warning signs of vulnerability, which can sometimes be acted upon at low cost. Our findings allowed us to identify the practical implications and make a number of preventive recommendations