Water network partitioning represents one of the best methodologies for improving water balance and pressure control of a water distribution system in order to reduce water leakage. These techniques can be applied with greater effectiveness defining a smaller permanent network district, called a District Meter Area (DMA), achieved by the insertion of gate valves and flow meters. If the DMAs are isolated subsystems (sectors), such that each zone is fed by its water source (or water sources) by closing gate valves in the network pipes that link the DMAs, the process can be called water network sectorization (defining an isolated DMA (i-DMA)). The traditional criteria for the design of network DMAs and i-DMAs are based on empirical suggestions (number of properties, length of pipes, etc.) and on approaches such as ‘trial and error’, even if used together with hydraulic simulation software. Nevertheless these indications and procedures are very difficult to apply to large water supply systems because the insertion of gate valves modifies the original network layout and may worsen, also considerably, the hydraulic performance of the water network. Recently some techniques, based on graph theory principles that allow simplification of the network partitioning and sectorization, and to find optimal solutions heuristically, have been proposed in the literature. In this paper the sectorization problem has been examined comparing different techniques, proposed by the authors, using the same water networks and performance indices and testing different possible i-DMA layouts.