The solution of pipe network problems can usually be obtained by orthogonal mesh and nodal approaches. However, when the size of a network becomes very large, these methods may not be efficient. In such a case diakoptics may be used. Essentially this approach tears the given network into two or more smaller subnetworks, thereby reducing the size of the matrices involved and saving computation time. So far most research in the area of diakoptics has been confined to problems where all the external flows are specified. Although the fictitious branch method has been incorporated into diakoptics to solve mixed flow- and pressure-specified problems it cannot satisfactorily solve problems with many pressure specified nodes. In the present work, a method for solving mixed specification problems is developed based on mesh and nodal diakoptics, incorporating partitioning. The diakoptics technique for the solution of mixed specification problems is found to be more efficient than conventional partitioning methods.