The Water Safety Plan (WSP) for the city of Salta (Argentina) is presented and discussed. To develop this WSP, we used an adapted version of the methodology proposed by the World Health Organization (WHO). The new method included a preliminary weighting procedure to assess the relative importance of different parts of the system, and a more systematic estimation of the magnitude of control measures. These modifications allowed the definition of a variety of risk reduction strategies. The risk assessment step was performed during participatory workshops with members of the local water company. The Initial Risk for the entire system was 30.2%, with variations among processes, subprocesses and components. More than 60% of the hazardous situations identified require control measures to reduce the risk below an acceptable threshold. If all control measures were successfully implemented, the Final Risk could be lowered to 17.7%. Methodological changes introduced allowed a more detailed analysis of the risks and can be an important improvement of the assessment procedure.