Significant leakage in pressure pipe systems may be detected by discrepancies in flow monitoring data from the system. Such discrepancies may exist between the measured flow volume of treated water leaving a plant and the sum of metered volumes received by users or among different points of distributed metering. However, inaccuracies in meters, completeness of metering, unrecorded connections, etc. make assembling detailed information problematic. Often, the discrepancies in a water supply system are simply referred to as “unaccounted for water”.