> For the complete documentation index, see [llms.txt](https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](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).

# 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.