In this paper, a new model based approach to leakage localization in drinking water networks is propose based on generating a set of structured residuals. The residual evaluation is based on a numerical method based on an enhanced Newton-Raphson algorithm. The proposed method is suitable for water network systems because the non-linearities of the model make impossible to derive analytical residuals. Furthermore, the computed residuals are designed so that leaks are decoupled, which improves the localization of leaks with respect to other existing methods. Finally, the Hanoi water network benchmark is used to illustrate the results of the proposed approach.