1. A method of automatically calibrating a water distribution model of a water distribution network, including the steps of: (A) selecting calibration parameters including at least one of pipe roughness, junction demand, and link status; (B) collecting field observed data including a pipe flow measurement and a junction pressure measurement for at least one point in the water distribution network, and including corresponding loading conditions and boundary conditions that existed in the network when said field observed data was collected; (C) generating a population of trial solutions that comprise a set of calibration results, using a genetic algorithm; and (D) running multiple hydraulic simulations of each trial solution to obtain a set of predictions of pipe flows and junction pressures at selected points in the network, corresponding to the different loading conditions and associated boundary conditions when the field observed data was collected.