This work describes the corrosion management of carbon steel structures of a firewater distribution system under laboratory conditions. The influence of operational modes i.e. regular replacement and extended stagnant condition of firewater were tested. Corrosion rate at different experimental conditions was determined and the corrosive bacteria were enumerated using conventional microbial culture methods. Denaturing gradient gel electrophoresis showed a significant variation in bacterial diversity under the different test conditions. Raman spectroscopy identified iron oxide phases like lepidocrocite, goethite, hematite, magnetite and the underlying corrosion mechanism was described. Based on the results obtained a plausible carbon steel corrosion management was explained.