Large earthquakes often damage water pipelines and disrupt the functionality of water distribution systems (WDS). This paper investigates the hydraulic performance of WDS following an earthquake, taking into account the post-earthquake firefighting capacity of the system and the corrosion deterioration of pipelines. The seismic failure probability for corroded water pipes is calculated using a modified ALA fragility function, and hydraulic simulations are performed using the Water Network Tool for Resilience (WNTR). Water serviceability and the generalized resilience index are used as measures to determine the hydraulic performance of the WDS, which is evaluated under various network ages and seismic intensities. The framework developed in this study is exemplified for the ZJ WDS. The results indicate that although firefighting does not significantly reduce performance measures, it is necessary to consider it in recovery plans since more customers are likely to lose water supply due to post-earthquake fires. The hydraulic behavior is worst in older WDS or those subjected to higher seismic magnitudes. Due to the scenario earthquake event, water serviceability reduces as the WDS ages, and the older networks require longer recovery times. Therefore, corrosion deterioration has a significant influence on the systemlevel seismic hydraulic performance.