5.7.4 Corrosion problems due to iron and sulphur bacteria

Iron and sulphur 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 sulphuric acid from sulphides or elemental sulphur

• 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 sulphur bacteria populations may be detected due to aesthetic impacts. Customer complaints should trigger an investigation.