In this paper the analysis of water distribution networks consisting of a large number of pipes is studied. The Newton’s method is used for solving the non-linear system of continuity equations which are written in terms of nodal heads. It is shown that the reliability of the method depends critically on the suitability of initial guesses. In other words, by increasing the number of unknowns, poor initial guesses will result in the divergence of the problem. Subsequently, the performance of an FAS-V cycle multigrid technique is examined as a convergence accelerator for the Newton’s method. It is concluded that this technique, considerably, reduces the number of iterations, and even poor initial guesses approach the convergence domain readily without the need for any hydraulic corrections of discharges.

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