AbstractThe paper develops a new method for optimized calibration of large‐scale non‐linear water networks. Calibration requirements are first discussed with relevance to the limited monitored operating data, the ill‐defined network parameters and the potential benefits of more accurate network simulations for analysis and control purposes. A formulation is then made which incorporates simultaneous adjustment of network physical parameters and related operational data in order to force agreement between measured and simulated variables. The system non‐linear response is represented by a high‐dimensional set of linear‐equations relating controllable adjustment parameters to the observed discrepancies in operating conditions. Quadratic performance indices, with optional user‐defined weighting factors, are shown to be most appropriate for the control variables. Use of a hierarchical optimization technique permits a solution to be obtained to the problem of high dimensionality with constrained controls and variable performance factors. Application of the scheme to a test distribution system leads to optimal adjustment of all the permitted variables to give the best overall solution for the available measurements. An important practical feature is the ease with which engineering experience can be incorporated to yield alternat