Leaks are present to some extent in all water-distribution systems. This paper proposes a leakagelocalisation method based on the pressure measurements and pressure sensitivity analysis of nodesin a water distribution network. The sensitivity analysis using analytical tools is not a trivial job ina real network because of the huge non-explicit, non-linear systems of equations that describe itsdynamics. Simulations of the network in presence and absence of leakage may provide anapproximation of this sensitivity. A fault isolation algorithm which correlates on line the residuals(generated by comparing the available pressure measurements with their estimation using amodel) with the fault sensitivity matrix is used. The proposed algorithm has been applied insimulation to a DMA (District Metered Area) in the Barcelona Network using EPANET software.The results obtained were promising