The intertidal zone in marine environments is particularly susceptible to high rates of steel corrosion, causing a significant risk to marine and costal infrastructure. This is a result of the electrochemical environment, but also in many cases, microbial colonisation of the steel structure. The combined effect is referred to as Accelerated Low Water Corrosion (ALWC). In this study, we have carried out 16S rDNA sequencing of material recovered from corrosion samples, seawater and bed sediment to identify the populations responsible for ALWC and their potential sources in the environment. Samples are selected from three different UK sites- two sites with evidence of ALWC (Shoreham and Newhaven ports) and one without (Southend-on- Sea).