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After a leak or flood, two questions decide how worried to be about mold: how dirty was the water, and how long did things stay wet? This checker asks those questions plus what got soaked, then sorts each material into keep-and-dry, clean, or replace, using EPA's water damage guidance and the water categories defined in the IICRC S500 standard. It runs in your browser and sends nothing anywhere.
With JavaScript off, use the tables below: find your water source to get its category, then look up each wet material.
The IICRC S500 is the restoration industry's standard for water damage work, and its three categories are how contractors and adjusters describe what came into your house. The definitions and examples below are from the S500 as reprinted in Restoration & Remediation magazine; Extension flood guidance uses the same three groups under the names clean, gray and black water.
| Category | Definition | Examples |
|---|---|---|
| 1, clean | Originates from a sanitary water source | Broken supply lines, sink or tub overflows with no contaminants, appliance supply lines, falling rainwater, a broken toilet tank |
| 2, grey | Contains significant contamination and could cause discomfort or sickness if touched or swallowed | Dishwasher or washing machine discharge, a toilet bowl overflow with urine but no feces, seepage through a foundation from hydrostatic pressure |
| 3, black | Grossly contaminated, and can contain pathogenic, toxigenic or other harmful agents | Sewage, toilet backflow from beyond the trap, ground surface water and water rising from rivers or streams |
One caution for reading the table: categories aren't fixed. According to a summary of the 2015 edition in Cleanfax, the standard now says time and temperature affect how contaminants multiply and so can change the category. A supply-line leak that soaked carpet over a long, warm weekend may no longer be clean water by the time anyone looks at it. That's why the checker escalates its answer when things have been wet for more than two days.
EPA's water damage table for schools and commercial buildings, which is the most detailed thing the agency publishes on the subject, is built around responding within 24 to 48 hours. Past that point, or once growth appears, EPA sends readers to its remediation guidance instead. The agency is careful to say the window is a guideline, not a guarantee: mold can grow on materials that were dried within 48 hours, and it doesn't always appear after. In a Nashville summer, when the outdoor dew point sits in the 60s every hour of the day, wet materials dry slowly unless dehumidifiers are running, so treat the window as tight.
| Material | EPA's guidance for clean-water damage within 24–48 hours |
|---|---|
| Ceiling tiles; fiberglass or cellulose insulation | Discard and replace |
| Carpet and backing | Extract water, dry within 24–48 hours with dehumidifiers and fans, dry the subfloor too |
| Drywall | Dry in place if not swollen and seams are intact; otherwise remove and replace |
| Wood surfaces | Dry promptly; take care with hardwood floors; pry paneling away to dry behind it |
| Vinyl, linoleum, ceramic | Clean and dry, check and dry the underflooring |
| Concrete or block | Remove water, dry with dehumidifiers, fans or heat |
| Upholstered furniture | Extract water and dry; drying within 48 hours may be hard |
| Books and papers | Discard non-valuable items; photocopy or freeze valuable ones |
With contaminated water, EPA says those clean-water steps don't apply as written: protective equipment and containment are required, and someone experienced with contaminated water should be consulted.
A "lower" result means drying now is likely to head off a mold problem. Anything higher means calling for help is reasonable, and for sewage or creek water it's the safer choice. For the full Nashville picture, including Metro permits and floodplain maps, read mold after a flood or leak. To understand what a professional cleanup includes, see mold remediation. Sources: Restoration & Remediation, IICRC water categories; Cleanfax, S500-2015 key terms; Alabama Extension, Drying Out After a Flood; EPA, Mold Remediation in Schools and Commercial Buildings, chapter 4; EPA, Homeowner's and Renter's Guide to Mold Cleanup After Disasters; EPA, A Brief Guide to Mold, Moisture and Your Home; EPA, chapter 3.
Falling rainwater is listed as a Category 1 example in the S500 definitions, and Extension guidance calls a roof leak clean water. If it soaks through dirty insulation or sits for days, it can degrade to a higher category.
After clean water, EPA says carpet can be dried if the water is extracted and the carpet and subfloor are dried within 24 to 48 hours. After sewage or floodwater, plan on replacing it.
Yes. Insurance agents, property managers and neighborhood groups are welcome to link to it. It is free and collects nothing.
We are a referral service and send nobody out ourselves. Leave your town and a line about what is going on, and a local, independent mold business will phone you to talk it through and quote. Water still running? Close the main shutoff or the fixture valve before anything else.