Water damage classification uses three categories that determine appropriate restoration methods and safety protocols. Category 1 (Clean Water) originates from sanitary sources like broken supply lines or rainwater and poses minimal health risks, requiring standard drying procedures. Category 2 (Gray Water) can contain contamination that can cause illness if contacted, including washing machine overflows or water that has been standing long enough to begin degrading. Category 3 (Black Water) consists of grossly contaminated water which can contain pathogenic, or other harmful agents from sources like sewage backups or flooding from rivers. Each category requires different restoration approaches, safety protocols, and material removal decisions to protect occupant health.