Our paper presents an analysis of French public management of drinking water vulnerability. The analysis is based on observation and comparison of two case studies. Each case describes the decision process leading to closure of some water catchments in favour of a single interconnected water catchment point. The second case (Val d’Adour, Hautes-Pyrénées) departs from the first situation (Saint-Nicolas-de-la-Grave, Tarn-et-Garonne) by a series of bans on tap water consumption upstream of this decision. It seems that water resources contamination from agricultural non-point source pollutions is an “ordinary risk ”. It is acknowledged but does not cause any problem so long as chemical treatments ensure respect of drinkability standards. This situation does not help implement preventive measures and is probably also due to the absence of an asserted social demand. At present consumer requirements in France focus on tap water quality and price rather than on the quality of the process being used to produce it. In the management dynamic of this “ordinary risk ” in the cases studied the prevailing logic is “palliative ” management of the treatment of causes: only the symptoms are treated through technical or curative solutions claimed to be sustainable. A vicious circle is thus generated: the daily management stresses the vulnerability of water resources which in turn weakens the local action system. This logic of palliative management is symptomatic of catchment basin a “disengaged public action ”, characterized by disengagement regarding treatment of water resources pollution whether in situations of potential or of actual risk. The decisions taken to ensure the continued existence of water supply and respect of drinkability standards highlight the chasm between responsibilities in drinking water management and the actual “coping capacity ” of locally elected authorities in the treatment of water resources vulnerability.