Cat 3 black water carries bacteria, viruses, parasites, and chemical contamination. Sewage backup, hurricane floodwater, and bayou flooding all qualify. Full PPE, IICRC S500 disposal protocols, EPA hospital-grade disinfection, ATP verification.
Category 3 water (per IICRC S500 standard) is the most contaminated water category restoration crews encounter. Defined as 'grossly unsanitary' with pathogenic and toxigenic agents, Cat 3 sources include sewage backup, rising flood water from rivers/bayous, hurricane storm surge with sewage mixing, and toilet overflow.
Cat 3 cleanup is NOT optional homeowner DIY work — pathogens persist in porous materials and contaminate adjacent areas through cross-contact. Standard IICRC S500 protocols require full PPE (Tyvek + P100 respirators), HEPA-filtered negative pressure containment, EPA-registered hospital-grade disinfectants applied twice, porous material disposal, and ATP testing verification before reoccupation.
Sanitary water from clean source: supply line break, ice maker line, broken pipe. Drinking-water quality at source.
Standard extraction with antimicrobial. Wet-vac OK on hard surfaces if within 48 hours.
Significant contamination from gray water: dishwasher drain, washing machine drain, aquarium burst. Soap and food particles.
Required IICRC protocols. Antimicrobial standard. Pad and carpet often replaced.
Grossly unsanitary with pathogens: sewage backup, river flooding, toilet overflow, hurricane storm surge. Bacterial, viral, parasitic load.
Full PPE. HEPA containment. Porous materials disposed per S500. EPA hospital disinfectant. ATP verification.
Toilet overflow, main-line backup
Storm-driven contamination
Cat 3 by definition
Saltwater + sewage combined
Tyvek + P100 respirators
Negative pressure isolation
Decon verification
Health-safe certificate
Dispatcher screens for Cat 3 exposure, evacuates affected areas.
Full PPE deployed. Negative pressure containment established.
Biohazard-rated extraction equipment. Affected zone documented.
IICRC S500 disposal. Manifested biohazard waste.
Hospital-grade two-pass. EPA registration numbers logged.
Air movers + dehumidifiers. ATP confirms decontamination before reoccupation.
Full PPE crews. IICRC S500 protocols. EPA disinfectants. ATP verification.