No consensus currently exists on how to measure and evaluate Critical Infrastructure (CI) resilience. Attempting to use the public’s declared coping capacity as a target for CI resilience, this paper explores how to develop relevant resilience performance measurements that enable comparison to the tolerance levels of the general public. To do so, one must first establish the normal performance of the system and the applicable performance measures. Then, a survey is used to convert public perception into these measures as to enable comparison with the technical resilience performance. The CI resilience will be presented through a family of so-called resilience triangles which will illustrate the evolution of the performance, before, during and after a crisis event. A case study of the Municipal Water Network of Barreiro, Portugal, is used. The overall performance is preferably described with the categories quality, quantity and delivery. In quantifying the performance the importance of what is being assessed, to what hazard and for which end-user became evident.