Analyses of potable water distribution systems are routinely accomplished by the use of computer modeling. A municipality or water system manager will be able to furnish data such as system maps, as-built construction drawings, elevation contours, manufacturer's pump curses, storage reservoir data, water supply, and sales records. The engineer, however, is required to investigate further to secure that data required to perform an accurate system analysis. In building a system's network model, one begins by reducing the system map into a series of lines or pipes, connecting junctions where two or more pipes are connected. The number of pipes to be included in a network model is a function of the degree of accuracy desired and the capacities of the computer hardware and software. Field testing is required to verify or calibrate a computer network model. T. M. Walski discusses possible inaccuracies found in network modeling and suggests several calibration methods.