Abstract: A water leakage monitoring system including a water leakage position estimator which includes a periodic data acquiring unit for fetching predetermined-period flow rate pressure data stored in a monitoring device, and for fetching a signal related to a flow rate change and pressure changes expecting a water leakage reaction time calculating unit for calculating a pressure reaction time lag between two pressure changes, a pressure propagation velocity estimating unit for estimating a pressure propagation velocity using the pressure reaction time lag and a distance between two pressure gauges located in a water distribution block stored in a pipeline network map data, and a flow rate change position estimating unit for receiving a signal related to the flow rate change, and estimating a flow rate change position using pressure propagation velocity and a flow meter and pressure gauge locating positions of the pipeline network map data.