Fire demands can have a significant impact on the size of a water distribution system. These demands create additional localized stress on the water system and may induce undesireable areas of low pressures. Sound engineering design practice dictates that the distribution system be capable of delivering all fire flows at the required minimum pressure. The application of computer network models provides an efficient and reliable approach for computing these flows and determining their impacts on system performance. Current fire flow models require changes in the network structure and associated hydraulic equilibrium equations or are based on a repetitive trial and error process. The result of using current models is inefficient performance at a greater cost. This paper describes an explicit and rigorous model that is able to directly perform accurate fire flow calculations under a wide range of network loading and operating conditions. The method is formulated analytically from pressure flow equilibrium relationship to exactly meet targeted minimum pressure requirements at the subject nodes. The proposed approach is illustrated using an actual water distribution system. The method is shown to be robust and efficient and converges in an expeditious manner. Also, the method is simple to understand and can be effectively implemented in any existing hydraulic network analysis model. Such capabilities will greatly enhance the ability of water engineers to effectively utilize hydraulic network modeling to determine the adequacy of the water system to deliver the required flows and to define necessary facility improvements at minimum cost. Enhancement of distribution system design, planning, and management is a principal benefit of the methodology.