Grossly contaminated water — biohazard requiring professional decontamination.
Category 3 (black water) is grossly contaminated and can contain pathogens, toxins, and hazardous substances. Sources: sewage backup, flooding from rivers/oceans, toilet overflow with feces, standing water that has supported microbial growth. IICRC S500 requires removal of porous materials contacted by Category 3 water.
