# 5.7.4 Corrosion problems due to iron and sulfur-metabolising bacteria Iron and sulfur-metabolising bacteria contribute to the corrosion of iron and steel well pipes and drinking-water mains, with corrosion starting from either inside or outside. Microorganisms may cause corrosion by: * depleting dissolved oxygen * producing corrosive metabolites * producing sulfuric acid from sulfides or elemental sulfur * participating in the electrochemical cathodic process. The presence of these organisms in water may indicate a potential for corrosion of cast iron mains and storage tanks. It can also indicate biodeterioration of certain construction materials, including non-metallic materials (e.g. plastics, rubber jointing compounds, pipe lining materials). These materials provide organic nutrients and encourage the growth of microorganisms such as *Pseudomonas aeruginosa*. Changes to iron and sulfur bacteria populations may be detected due to aesthetic impacts. Customer complaints should trigger an investigation. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-2/chapter-5/5.7-nuisance-organisms/5.7.4-corrosion-problems-due-to-iron-and-sulphur-bacteria.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.