The ANSI/IICRC S500 Standard for Professional Water Damage Restoration — the industry bible.
S500 (4th Edition, 2021) defines water damage categories (1-3), classes (1-4), inspection procedures, extraction methods, structural drying requirements, and documentation standards. All IICRC-certified restoration work follows S500 protocols.
Category 1 Water (Clean Water)
Sanitary water from broken supply lines, melting ice, or rainwater — lowest health risk.
Category 2 Water (Gray Water)
Contaminated water with chemical or biological content — moderate health risk.
Category 3 Water (Black Water)
Grossly contaminated water — biohazard requiring professional decontamination.
Class 1 Water Damage
Least amount of water absorption — affects only part of a room.
