This paper summarizes Pacific Environmental Services' efforts to implement a water distribution modeling software package at two US Air Force Bases. Model development was required to perform comprehensive hydraulic analyses of each potable water distribution system. The model was also used to evaluate specific operational scenarios, as well as evaluate and optimize several construction projects under consideration. These efforts were part of a bigger project to conduct a water vulnerability assessment that included evaluations of the redundancy of facilities, the need for back-up treatment systems, the ability of facilities to deliver adequate pressure for both normal use and fire suppression, and manpower requirements. The selected modeling package, WaterCAD, is a computer model capable of predicting flowrates, pressures, and water quality conditions for differing scenarios. Model input data describing the geometry and characteristics of all distribution system components were collected. Field-derived pipe roughness factors were developed as a result of on-site flow testing. Calibration was performed to ensure that the model accurately predicted pressures, flowrates, and water quality characteristics measured through field-testing. Once calibration was completed, several scenarios were postulated and run to predict and/or analyze the impact of different operating conditions. Several proposed construction projects were evaluated to determine the best combination of piping changes, operational modifications, and/or system upgrades to remedy known low-pressure areas of the system. The model was also used to predict storage tank levels at each Base in order to determine if operational changes could be made to minimize stagnant water formation in each tank. Finally, the model was linked to each Base's geographic information system (GIS) to allow for simple updating of WaterCAD's input files, as needed in the future. Includes 3 references, figures.