FireFlow

This program is a freeware, EPANET based tool, which will calculate the available flow at network junctions while a minimal pressure is kept at demand junctions.

FireFlow can run in a "Steady State" mode or perform an "Extended Period Simulation" (EPS).
With this tool you can build the network with EPANET and export it to an INP file by using the File menu, then chose the Export from the Network menu.