Action, at various levels, is necessary to ensure optimum management of drinking water quality in all distribution networks: Controls of some specific parameters at outlet from drinking water treatment plants, such as dissolved organic content, corrosivity, particle content, and a guarantee of perfect disinfection; A good knowledge of the network through the application of hydraulic models and the use of quality modules to predict chlorine decrease, bacteria proliferations and particle deposit zones. These modelings are now possible thanks to the new quality modules of the Piccolo software we have developed; A network monitoring strategy based on the choice of sampling sites using models, and the use of online sensors. For this purpose the authors discuss the development of residual chlorine microsensors based on microelectronic techniques, and analyzers which automatically detect coliforms; Quality management requires an intelligent chlorination strategy, with the right dose being applied in the right place, and also the use of more innovative solutions, as used in the satellite membrane treatment demonstration plant, which combines ultrafiltration with nanofiltration. Distribution networks are vast reactors which are a continuation of the drinking water production plant, and it is important to develop appropriate modern monitoring, prevention and treatment solutions for these networks, in order to guarantee water supply reliability, quality and security.