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Iron bacteria and biofilms wreak havoc on stainless steel

Iron bacteria and biofilms wreak havoc on stainless steel

Iron bacteria and biofilms wreak havoc on stainless potable water distribution system within just 6 months

Corrosion of stainless steel potable water service line(s) at a large dairy farm had occurred within six months of commenced operation. Microbe Detectives was hired to analyze water samples from this system and assess the likelihood of Microbiologically Influenced Corrosion (MIC).

Four water samples were analyzed using Microbe Detectives’ DNA Sequencing methodology. This analysis identified and quantified nearly all Bacteria, Archaea, and Eukarya (e.g., fungi, algae, amoeba, etc.) known in environmental science that were present in each water sample. The data was then checked for the presence of microbes known to cause MIC. Estimated quantities of MIC microbes were measured as 16S gene copies/mL for bacteria and archaea, and as 18S gene copies/mL for eukarya.

The surprising truth: iron-utilizing MIC bacteria were the main story.

Iron associated bacteria are behind many cases of MIC in stainless steel potable water systems. Contrary to popular belief, sulfate-reducing and sulfur-oxidizing bacteria are often absent in these cases. Our research has shown that untreated freshwater sources, such as reservoirs, rivers, or bayous, provide the perfect breeding grounds for these destructive iron associated microbes. Unfortunately, the client’s system fell victim to this reality. A summary of the MIC microbes observed are shown below, and indicate iron associated MIC microbes were the primary story.

The Peril of Biofilms

But that’s not all… Biofilms develop highly diverse ecologies of hidden and resilient populations of microbes, and create an ideal environment for under-deposit MIC corrosion. Our DNA sequencing approach revealed insights on biological diversity within the client’s system. Results suggested the presence of biofilms near two sample locations after chlorine-dioxide (ClO2) treatment was applied.

The evidence of ClO2’s kill effect was observed through the lower estimated microbe quantities in samples 11944 (3,389) and 11947 (3,222), in comparison to samples 11948 (586,811) and 11949 (15,531,905). On the other hand, the lowest microbe estimated quantities corresponded with stronger evidence of potential biofilm presence. Samples 11944 and 11947 exhibited biodiversity values that were 2X+ greater than samples 11948 and 11949. Visualize these findings with the summary tables and charts below.

Get the needed modern tools to properly diagnose and prevent microbial influenced corrosion

Protect your stainless steel water distribution systems by taking advantage of modern DNA tools that are applied by WaterTrust. Discover the power of advanced technology and contact us today to learn more.


1.“Microbiologically Influenced Corrosion of Stainless Steels by Water Used for Cooling and Hydrostatic Testing,” G. KOBRIN, et al Nickel Development Institute and K.A. SELBY, Puckorius & Associates.