The division of a network in different sectors is a usual practice in Water Companies. It improves the management of the network in different senses. Sectors have more homogenous characteristics and need specific cares and treatments that is not the same all through the network. Specifically for leakage detection and assessment it is interesting to know the performance of the sector before any leakage detection strategy is applied. In this paper a characterisation methodology for the sectors is presented. This methodology is based on the knowledge provided by the company but has been analysed using clustering techniques. The main objective of the classification was to find out which were three interesting pilot sectors for the leakage detection methodology study. A desicion tablefor the selection have been developed based on these classifications. For the desicion Nevertheless the characterisation itself demonstrated to provide information to the experts about the Network.