Industrial facilities rely on complex networks of pipes, tanks, and mechanical components to keep operations running smoothly. Yet one often-overlooked threat can quietly degrade these systems from the inside out: microbial corrosion. Also known as microbiologically influenced corrosion (MIC), this form of deterioration results from the activity of specific microorganisms that accelerate metal loss, structural weakening, and equipment failure.

Left unaddressed, MIC can disrupt production, contaminate products, and cause costly outages. According to the Institute of Corrosion, corrosion eats about 3% of global GDP annually, illustrating the massive economic burden industries face. Because MIC behaves differently than traditional corrosion, understanding how it develops—and how to detect it early—is essential for protecting critical assets. This post explains what microbial corrosion is, why it occurs, and how local corrosion testing companies can help industrial operators identify and mitigate it before major damage occurs.

Understanding Microbial Corrosion

Microbial corrosion occurs when microorganisms, such as bacteria or fungi, cause or accelerate the breakdown of metals. While metal deterioration typically stems from chemical or electrochemical reactions, MIC involves biological activity that influences these processes. The organisms responsible for MIC thrive in diverse industrial environments—from oil and gas pipelines to water treatment facilities, chemical plants, and storage tanks.

A common group of culprits is sulfate-reducing bacteria (SRB). These microbes thrive in oxygen-deprived environments and produce hydrogen sulfide, a corrosive compound that attacks steel and other metals. Other organisms, such as iron-oxidizing bacteria, acid-producing bacteria, and slime-forming species, can also contribute to corrosion by creating deposits that trap moisture, alter pH, or generate corrosive byproducts.

What makes MIC especially challenging is its ability to progress unnoticed. Unlike typical corrosion, which may cause visible rust or metal thinning, microbial corrosion often occurs beneath biofilms or deposits that conceal early warning signs. That is why working with local corrosion testing companies is essential—they use specialized tools to detect microbial activity in places internal teams may not be able to assess fully.

Recognizing the Causes of Microbial Corrosion

Microbial corrosion develops under specific conditions that allow microorganisms to colonize industrial equipment. Moisture, nutrients, and stagnant or low-flow areas create ideal environments for microbial growth. When fluids slow down or remain still, oxygen and nutrient gradients form on metal surfaces, enabling bacteria to thrive and form biofilms.

Biofilms act as protective shelters for microorganisms. Within these slimy layers, bacteria multiply quickly and create microenvironments with different chemical properties than the surrounding material. For example, areas beneath a biofilm may become oxygen-starved, accelerating corrosion in localized patches. This type of hidden deterioration illustrates the need for local corrosion testing companies, which can evaluate hard-to-reach surfaces and determine if microbial activity is present.

Additionally, industrial processes that involve water—such as cooling systems, fire protection networks, and storage tanks—are particularly vulnerable. When water quality is not monitored or treated properly, microorganisms flourish and contribute to MIC. Temperature fluctuations, dissolved metals, and chemical additives can also influence microbial behavior.

Identifying the Signs of Microbial Corrosion

Although MIC can hide beneath layers of deposits, certain symptoms may indicate its presence. Unexplained pitting, for instance, is a major red flag. MIC often causes highly localized metal penetration, which can be deeper and more severe than traditional corrosion mechanisms. Unexpected leaks, premature equipment failures, and sudden drops in system performance also warrant investigation.

Sometimes operators notice a rotten-egg smell, which is associated with hydrogen sulfide produced by SRB. Other signs may include the presence of slime or unusual discoloration on internal surfaces. Because these clues can be subtle or ambiguous, industrial teams often rely on local corrosion testing companies for definitive assessment. Professionals use advanced analytical techniques—such as microbiological sampling, metal coupon testing, and surface analysis—to confirm whether MIC is occurring.

It is important to emphasize that DIY testing is never advisable. Microbial analysis requires controlled laboratory environments, sterile collection methods, and specialized equipment that typical industrial facilities do not possess. Attempting to identify or interpret MIC without professional support can lead to inaccurate conclusions and missed warning signs, increasing the risk of failure.

Examining the Impact of Microbial Corrosion

MIC can have serious consequences for industrial systems. Structural degradation is the most obvious danger, as metal loss weakens pipes, tanks, and machinery. Pitting caused by microorganisms can penetrate deeply into metal surfaces, creating the potential for sudden rupture. In industries that handle hazardous chemicals or pressurized systems, this risk poses major safety concerns.

In addition to physical damage, microbial corrosion can contaminate products or process fluids. This is especially problematic in food processing, pharmaceuticals, and water treatment, where purity standards must be strictly maintained. Microbial contamination can cause production shutdowns, product recalls, and regulatory violations—issues that significantly increase operational costs.

The financial implications extend far beyond repair expenses. Downtime, emergency shutdowns, insurance claims, and compliance penalties all contribute to the economic burden. Because of these risks, partnering with local corrosion testing companies is a strategic decision. Professionals can pinpoint the root causes of MIC and recommend corrective actions before the situation escalates.

Detecting Microbial Corrosion With Professional Methods

Detecting MIC requires a systematic approach that blends visual inspection, chemical analysis, and microbiological testing. Professionals begin by examining systems for signs of deposits, biofilms, or pitting. They then collect samples from affected areas, ensuring proper handling to preserve microbial integrity.

Laboratory analysis may include culture-based methods, molecular testing, scanning electron microscopy, or energy-dispersive X-ray spectroscopy. These techniques reveal the presence and concentration of microorganisms that may contribute to corrosion. Such assessments allow local corrosion testing companies to provide accurate diagnoses and guide targeted treatment plans.

System modeling and fluid testing also play crucial roles. Professionals evaluate water chemistry, flow patterns, and environmental conditions to understand why microorganisms are thriving. This holistic approach is essential for preventing recurrence rather than simply treating symptoms.

Because MIC is multifaceted, relying on DIY kits or internal assumptions is inadequate. Skilled professionals bring comprehensive expertise, specialized tools, and laboratory precision—resources that are indispensable when protecting valuable industrial assets.

Preventing Microbial Corrosion Through Professional Intervention

Prevention strategies depend on understanding the specific microbial activity within a system. Professionals may recommend biocides, filtration improvements, flow adjustments, or changes in water treatment programs. Mechanical cleaning may be necessary to remove biofilms and restore system integrity.

Working with local corrosion testing companies ensures that prevention plans are tailored, realistic, and based on scientific evidence. Industrial teams may be tempted to apply generic chemicals or flush systems without understanding the root cause, but such approaches often fail to eliminate microorganisms fully. Improper treatment can even worsen corrosion by disrupting system chemistry or damaging protective coatings.

Long-term prevention relies on ongoing monitoring. Regular testing enables teams to identify microbial activity early and adjust treatment strategies as conditions change. Professional oversight helps industrial operators maintain compliance, reduce risks, and extend the lifespan of equipment.

Evaluating the Value of Professional Support Over DIY Approaches

MIC is one of the most challenging corrosion mechanisms to diagnose and manage. Its invisible nature, biological complexity, and potential for rapid progression make it unsuitable for do-it-yourself approaches. Even highly skilled maintenance teams lack the specialized microbiological training and laboratory resources needed to detect subtle microbial patterns accurately.

This is where local corrosion testing companies provide tremendous value. Their expertise allows them to identify the type of microorganisms present, determine whether MIC is active, and design mitigation strategies tailored to the facility's environment. Attempting to handle MIC without professional support can delay proper treatment, increase costs, and jeopardize system integrity.



Microbial corrosion is a hidden yet significant threat to industrial systems, capable of causing severe structural damage, contamination, and financial loss. Early detection and prevention require a deep understanding of microbial behavior, specialized testing, and precise mitigation strategies. Because MIC often progresses unseen, working with local corrosion testing companies is essential. These professionals bring scientific insight, laboratory testing, and evidence-based recommendations that DIY efforts simply cannot match.

If you suspect microbial corrosion or want to protect your industrial infrastructure, we encourage you to work with experienced professionals who can safeguard your systems effectively. At Corrosion Testing Laboratories, Inc, we are committed to helping you detect, understand, and mitigate MIC with confidence—contact us today to get started.