A method of monitoring the quality of the water of a drinking water distribution network including on the one hand consumption meters and on the other hand in-line analyzers at surveillance points of the network for measuring at least one quality parameter of the water, in which method: - measurements from the analyzers (10a, 10b, etc.) are sent to a calculation unit (A), - the calculation unit (A) establishes estimated values of the level in the water of the parameter concerned at the various surveillance points in the network, and - measured values of te quality parameter at different surveillance points of the network are transmitted to a pre-alarm system (W), - and the pre-alarm system (W) compares the estimated values of the quality parameter and the values measured at various points of the network, an alarm being tripped if the difference between a measured value and an estimated value exceeds a predetermined threshold, characterized in that , for monitoring in real time: - meters (9a, 9b, etc.) equipped with remote meter reading devices are installed on branch connections to consumers, - consumption data from the various consumer meters (9a, 9b, etc.) is sent to the calculation unit (A), - the calculation unit (A) is programmed with a hydraulic model and a kinetic model of the decrease of the quality parameter concerned, and - the calculation unit (A) continuously updates the hydraulic model according to consumption data received from the consumer meters (9a, 9b, etc.), - an information on reverse flow.is transmitted to the pre-alarm system (W) from a meter (9a, etc.) and grouped information on reverse flow and quality parameter level are combined to increase the probability of detecting an abnormality in or an intrusion into the network. - measurements from the analyzers (10a, 10b, etc.) are sent to a calculation unit (A), - the calculation unit (A) establishes estimated values of the level in the water of the parameter concerned at the various surveillance points in the network, and - measured values of te quality parameter at different surveillance points of the network are transmitted to a pre-alarm system (W), - and the pre-alarm system (W) compares the estimated values of the quality parameter and the values measured at various points of the network, an alarm being tripped if the difference between a measured value and an estimated value exceeds a predetermined threshold, - meters (9a, 9b, etc.) equipped with remote meter reading devices are installed on branch connections to consumers, - consumption data from the various consumer meters (9a, 9b, etc.) is sent to the calculation unit (A), - the calculation unit (A) is programmed with a hydraulic model and a kinetic model of the decrease of the quality parameter concerned, and - the calculation unit (A) continuously updates the hydraulic model according to consumption data received from the consumer meters (9a, 9b, etc.), - an information on reverse flow.is transmitted to the pre-alarm system (W) from a meter (9a, etc.) and grouped information on reverse flow and quality parameter level are combined to increase the probability of detecting an abnormality in or an intrusion into the network. <EOS>