Fungi and Bacteria Exclusion
Written by Justin Goodman, CIC, MFHR, CRIS, CEO and Co-Founder, Total CSR
Published: September 17, 2026 · Last reviewed: September 17, 2026
In plain language: Fungi and bacteria exclusion means your insurance will not pay to clean up mold or bacteria growth, or to defend a lawsuit over it, even if a covered event like a pipe burst caused the moisture that led to the mold.
Technical definition: Fungi and bacteria exclusion is a standard provision in commercial property, general liability, and homeowners forms that bars coverage for loss, cost, or damage tied to the presence, growth, or remediation of fungus, mold, mildew, wet or dry rot, and certain bacteria, regardless of the covered cause that triggered it.
Fungi and Bacteria Exclusion at a Glance
| Attribute | Detail |
|---|---|
| Also known as | Mold exclusion, fungus exclusion, microbial matter exclusion |
| Category | Property and liability policy exclusion |
| Lines of business | Commercial property, CGL, homeowners, businessowners policy (BOP) |
| Industries most affected | Property management, habitational, construction, restaurants, real estate |
| Related forms or endorsements | CG 21 67 (Fungi or Bacteria Exclusion), CG 21 68 (Fungi or Bacteria Exclusion with Limited Coverage), CP 01 40 (Exclusion of Loss Due to Virus or Bacteria varies by state) |
| Who bears the risk | Property owner, landlord, contractor, or business named insured |
| Common solution | Limited fungi coverage endorsement or standalone environmental policy |
| Also interacts with | Water damage exclusion, pollution exclusion, ensuing loss provisions |
Key Takeaways
- Fungi and bacteria exclusion removes or restricts coverage for mold, mildew, and bacteria damage across most standard property and liability policies.
- Agencies see this exclusion trigger disputes constantly, because a covered water loss like a burst pipe often leads directly to an excluded mold claim within days.
- The most common misunderstanding is assuming a covered peril automatically covers everything that follows from it, including mold growth that develops afterward.
- A quick win is offering a limited fungi coverage endorsement upfront on any habitational, restaurant, or water-exposed risk, and documenting the client's decision either way.
What Is Fungi and Bacteria Exclusion in Insurance?
Fungi and bacteria exclusion is a policy provision insurers added broadly after mold litigation surged in the early 2000s, most famously following large homeowners verdicts in Texas that pushed carriers nationwide to tighten language. Insurers view mold and bacteria as slow-developing, maintenance-related conditions rather than sudden accidental losses, and they worry about open-ended remediation costs that can exceed the value of the underlying property. The exclusion protects carriers from paying for what they consider a preventable, gradually occurring condition rather than a fortuitous event.
A concrete example illustrates the mechanism. A restaurant's supply line bursts overnight, and water floods the kitchen and storage area. The property policy covers the water extraction, drywall replacement, and flooring. Three weeks later, an inspector finds mold growing inside the wall cavities because the space was not fully dried out. Under a standard fungi and bacteria exclusion, the carrier pays for the water damage but denies the separate mold remediation cost, even though the same burst pipe caused both problems.
Many carriers use ISO endorsement CG 21 67 to eliminate fungi and bacteria coverage entirely on the liability side, while CG 21 68 restores a small sublimit, often $50,000 or less, for cleanup tied to a covered occurrence. The distinction between these two forms matters enormously to a client facing a real claim, and agencies must know which one sits on a given policy before making any coverage representation.
How Does Fungi and Bacteria Exclusion Work?
- The covered event. A sudden and accidental loss occurs, such as a pipe burst, roof leak, or storm-driven water intrusion, and the property policy responds to the direct physical damage.
- The delay. Moisture remains trapped in walls, flooring, or HVAC systems, often because remediation was incomplete, slow, or the space stayed closed for days.
- The discovery. Mold, mildew, or bacteria growth appears, sometimes weeks or months later, and the insured reports it as a continuation of the original claim.
- The exclusion review. The adjuster separates the original covered water damage from the fungal growth and applies the fungi and bacteria exclusion to the mold portion specifically.
- The outcome. The carrier pays for the original covered damage but denies or sublimits the mold remediation, leaving the insured to cover the gap unless a limited fungi endorsement was in place.
Real Claim Examples Involving Fungi and Bacteria Exclusion
Apartment complex water intrusion during a vacancy period
A property manager discovered a slow roof leak above a vacant unit that had gone unnoticed for several weeks. The insurer paid for roof repair and interior drywall replacement under the covered peril but denied the extensive mold remediation across three units, citing the fungi and bacteria exclusion. The owner had not purchased the limited fungi coverage endorsement, resulting in a five-figure out-of-pocket remediation cost.
Restaurant walk-in cooler condensation claim
A restaurant owner filed a claim after discovering mold growth behind a walk-in cooler traced to a slow refrigerant leak causing chronic condensation. The carrier denied the entire claim, arguing the loss developed gradually rather than suddenly and was excluded as fungi damage regardless of any water component. The distinction between sudden accidental loss and gradual deterioration proved decisive, and the exclusion applied cleanly with no ensuing loss argument available.
Tenant lawsuit over respiratory illness in a habitational building
A tenant sued a landlord alleging mold exposure caused ongoing respiratory problems in a multi-family building. The landlord's CGL policy carried the CG 21 67 exclusion with no buyback, so the carrier denied defense and indemnity entirely under a reservation of rights that quickly became an outright denial. The landlord had to fund defense costs separately, illustrating why habitational risks often need a standalone pollution or mold liability policy.
Fungi and Bacteria Exclusion vs. Water Damage Exclusion: What Is the Difference?
Fungi and bacteria exclusion targets mold and microbial growth specifically, while water damage exclusion targets certain types of water intrusion such as flood, sewer backup, or seepage. Both exclusions frequently appear on the same claim because water damage often precedes mold growth, and agencies must evaluate them as separate but related coverage gaps.
| Comparison area | Fungi and Bacteria Exclusion | Water Damage Exclusion |
|---|---|---|
| Primary use case | Bars mold, mildew, and bacteria remediation costs | Bars flood, seepage, sewer backup, and similar water perils |
| Coverage / concept type | Standard property and liability exclusion | Standard property exclusion, often with buyback options |
| Typical exclusions | Nearly all fungi cleanup unless a limited endorsement applies | Flood and surface water, unless flood or water backup coverage is added |
| Who is most affected by errors | Habitational owners, restaurants, contractors | Basement-level businesses, flood-zone properties |
| Common mistakes | Assuming the original covered peril extends to resulting mold | Assuming standard property coverage includes flood or sewer backup |
What Are the Most Common Mistakes With Fungi and Bacteria Exclusion?
- Assuming a covered water loss automatically covers any resulting mold, when the exclusion typically applies to the mold portion separately regardless of the trigger.
- Confusing CG 21 67, which eliminates fungi coverage entirely, with CG 21 68, which restores a small sublimit, and misrepresenting which one applies to a client's account.
- Failing to offer the limited fungi coverage endorsement on habitational, restaurant, or basement-level risks, creating an E&O exposure when a client later discovers the gap.
- Not documenting a client's decline of fungi coverage in writing, leaving the agency without proof of an informed choice if a claim is later denied.
- Overlooking state-specific mandatory offer requirements, since some states require carriers or agents to offer limited fungi coverage on certain policy types.
How to Explain Fungi and Bacteria Exclusion to a Client
Explaining fungi and bacteria exclusion to a personal lines client
Your homeowners policy does not cover mold cleanup in most situations, even if a covered problem like a burst pipe caused the moisture. If a leak happens, drying out the area fast matters because delayed cleanup is exactly when mold takes hold and coverage disappears. We can look at adding limited mold coverage if you want extra protection.
Explaining fungi and bacteria exclusion to a small business owner
Your commercial property policy likely has a fungi and bacteria exclusion, which means mold cleanup after a water event often falls outside what the carrier will pay. Kitchens, basements, and any space with plumbing are the highest-risk areas for this gap. We can add a limited fungi endorsement now for a relatively small premium, which is much cheaper than paying for remediation out of pocket later.
Explaining fungi and bacteria exclusion to a CFO or risk manager
Your general liability and property forms both carry fungi and bacteria exclusions, and the specific endorsement on file determines whether you have any sublimit at all. CG 21 67 eliminates coverage completely, while CG 21 68 restores a limited amount, typically capped well below full remediation costs for a multi-unit or commercial property. Given your portfolio's water exposure, I recommend we review whether a standalone environmental or mold liability policy makes more sense than relying on the sublimit alone.
Frequently Asked Questions About Fungi and Bacteria Exclusion
Does homeowners insurance ever cover mold damage?
Homeowners insurance sometimes covers mold if it results directly and quickly from a covered peril, such as a sudden pipe burst, and the insured reports and mitigates it promptly. Most policies still cap mold remediation coverage at a low sublimit, often $5,000 or less, even when coverage applies. Gradual leaks, humidity, or poor maintenance almost always fall outside coverage entirely.
Can a business buy back fungi and bacteria coverage?
A business can often add limited fungi coverage through an endorsement, and ISO's CG 21 68 restores a modest sublimit for liability claims tied to a covered occurrence. Coverage limits typically range from $15,000 to $50,000 depending on the carrier and state. Businesses with higher mold exposure, such as restaurants or habitational properties, may need a standalone environmental policy instead of relying on the endorsement alone.
Why do insurers exclude mold and bacteria so broadly?
Insurers exclude mold and bacteria broadly because litigation in the early 2000s produced large, unpredictable verdicts tied to mold exposure claims, particularly in humid states like Texas and Florida. Carriers view mold as a slower-developing, maintenance-related condition rather than a sudden accidental event. The exclusion lets insurers price policies without absorbing open-ended remediation and bodily injury exposure.
Does the fungi exclusion apply if a covered peril caused the mold?
The fungi exclusion generally still applies even when a covered peril like a burst pipe caused the underlying moisture, because most policy language excludes fungi damage "regardless of any other cause." Some older or broader forms include an ensuing loss provision that can restore limited coverage in specific circumstances. Agencies should never assume the ensuing loss exception applies without reading the exact policy language.
What is the difference between CG 21 67 and CG 21 68?
CG 21 67 eliminates fungi and bacteria coverage from the CGL policy entirely, with no sublimit for cleanup or liability. CG 21 68 attaches the same exclusion but restores a limited sublimit, commonly in the $15,000 to $50,000 range, for fungi-related liability tied to a covered occurrence. Confusing these two forms is one of the most damaging errors an agency can make when representing coverage to a client.
Do restaurants need special mold coverage?
Restaurants face elevated mold risk because of constant water use, refrigeration condensation, and enclosed spaces like walk-in coolers, making them strong candidates for a limited fungi endorsement or standalone policy. Standard property and liability forms typically exclude the bulk of mold remediation costs a restaurant might face. Total CSR's training data shows restaurant accounts are among the highest-frequency mold denial disputes agencies report, largely because the exclusion is rarely discussed at binding.
Related Insurance Terms
- Pollution Exclusion: A liability exclusion barring coverage for contamination and pollutant discharge, which insurers often apply alongside or instead of the fungi exclusion when mold is classified as a pollutant.
- Water Damage Exclusion: A property exclusion limiting coverage for flood, seepage, or sewer backup, frequently the upstream cause of the mold growth that the fungi exclusion then bars from coverage.
- Ensuing Loss Provision: A policy clause that can restore coverage for damage resulting from an otherwise excluded cause, occasionally offering a narrow path back to coverage in fungi disputes.
- Limited Fungi Coverage Endorsement: An add-on form, such as CG 21 68, that restores a capped amount of mold-related coverage otherwise removed by the standard exclusion.
- Mold Remediation: The professional cleanup and removal process for fungal growth, whose cost is the exact expense the fungi and bacteria exclusion is designed to eliminate from standard coverage.
- Businessowners Policy (BOP): A packaged commercial policy combining property and liability coverage that typically includes the fungi and bacteria exclusion as a standard, non-negotiable provision.
Sources and References
- Insurance Services Office (ISO) reference via IRMI. Fungi Exclusion.
About the Author
Justin Goodman, CIC, CCIP, CISC, CLCS, CRIS, PCIA, QCLS, MFHR CEO and Co-Founder, Total CSR, Inc.
Justin Goodman is a third-generation insurance broker with over two decades in agency operations. He has trained more than 100,000 CSRs, account managers, and producers in commercial and personal lines coverage, from workers' compensation to construction risk. He was named 2024 Insurance Journal Agent of the Year and one of the nation's top five construction insurance experts by Risk & Insurance. He is the author of Retain, which applies cognitive science research on memory and knowledge transfer to insurance training, and speaks nationally on how agencies build durable technical expertise in their teams.