The system including a sensing device including a pressure sensor configured to measure pressure of water in a water system of a structure during a testing interval when a system shutoff valve of the water system is closed. The sensing device can be configured to generate pressure measurement data representing the pressure of the water as measured by the pressure sensor. The system also can include one or more processing units comprising one or more processors and one or more non-transitory storage media storing machine-executable instructions configured when run on the one or more processors to perform estimating an orifice size of a leak in the water system based on the pressure measurement data. Other embodiments are provided.