IICRC water Category 1/2/3 & Class 1-4
The IICRC S500 standard rates two things about a water loss: the Category (how contaminated the water is — 1 clean, 2 gray, 3 black) and the Class (how much water and how hard it is to dry — 1 to 4). Category drives the safety and demolition; Class drives the drying equipment. These are labeled reference definitions, not medical advice. Use them in the Category/Class helper.
| IICRC classification | Typical source / meaning | Handling / drying implication |
|---|---|---|
| Category 1 — clean water | Sanitary source: supply line, rain, melting snow | Degrades to Cat 2 in ~48–72 hr |
| Category 2 — gray water | Washing-machine/dishwasher overflow, sump failure | Contaminated — PPE, remove some porous materials |
| Category 3 — black water | Sewage, rising flood water, sea water | ⚠️ Health hazard — certified pros only, remove porous materials |
| Class 1 — least water | Small area, low porosity, minimal absorption | Fastest to dry |
| Class 2 — large area | Whole room with carpet + pad, water wicked <24 in | More air movers + dehumidification |
| Class 3 — greatest water | Water came from overhead, saturated ceilings/walls | Maximum drying capacity |
| Class 4 — specialty drying | Deep/bound water in hardwood, plaster, concrete | Special methods (heat, desiccant) |
Category rates how contaminated the water is; Class rates how much water and how hard it is to dry. Labeled reference definitions (IICRC S500) — not medical advice.