In recent years, many researchers have analysed the vulnerability of Water Distribution Networks (WDNs) from the hydraulic perspective. However, few works in literature have addressed the vulnerability problem from the topological point of view. This work adopts the information entropy to evaluate the topological vulnerability of a WDN from the character of its heterogeneity. The proposed method is based on the principle that a network with uniformly distributed centrality values exhibits a lower drop in performance in the case of partial failure of its components and therefore is less vulnerable. In order to demonstrate the proposed method, the paper presents two case studies, a real-world WDN of an Australian town and a network from the literature. Comparative analysis confirmed that a network with more homogeneous distribution of the nodal betweennes centrality values is less vulnerable against the random failure of its components than that of the one with heterogeneous distribution of these values.