Described herein are systems, devices, and methods for detecting leaks of liquids or gases in a transporting network. In one embodiment, a flow detector for detecting volume and direction of flow is attached to a system transporting such liquid or gas, changes are sensed over time, and data is sent to and from a controller. In alternative embodiments, static and dynamic states are identified and differentiated to identify relatively small leaks. In some embodiments, the transporting network is emptied in whole or in part, thereby allowing the measurement of relatively small leaks. In some embodiments, aggregate measurement data is processed to identify usage and performance features particular to the transporting network, which allows a continuous improvement in the measurement of leaks and flow direction. In some embodiments, corrective action is taken automatically, while in other embodiments human operators order corrective action.