Part of our job is to analyze fire protection water supplies. One of our nemesis is microbiologically influence corrosion (MIC). When looking for a lab to test for MIC, I received information from one of the testing laboratories who indicated where there is MIC, Legionella bacteria probably will also exist. Is this true? If so, are there documented cases?
We do not know of any documented cases linking MIC to Legionnaires’ disease. The major mode of transmission of Legionella is through aspiration. This would require a susceptible human to ingest water containing a concentration of Legionella bacteria. Since consumption of water from fire protection systems is unlikely and assuming your employees are generally in good health, the risk for Legionnaires’ disease is minimal.