Category 3 water includes sewage, floodwaters from external sources and other highly contaminated water carrying bacteria and pathogens. In a commercial building, a Category 3 event changes the restoration scope materially. Porous materials such as drywall, insulation and carpet that might otherwise be dried in place must be removed entirely because they cannot be adequately decontaminated. Personnel working in affected areas require appropriate protective equipment throughout the response. Anti-microbial treatment is applied more extensively, and the documentation requirements for the insurance claim are more detailed than a standard Category 1 water loss. Sewer backups, storm drain overflows and flooding from parking lots or exterior grade all qualify as Category 3, and each requires a response that accounts for contamination control in addition to structural drying.