Water Loss Class and Category
Plain-English categories 1, 2, 3 and classes 1 to 4.
Reference
Categories
- Category 1 Water from a sanitary source. Generally clean. Time and contact may shift to category 2 or 3.
- Category 2 Significantly contaminated water that could cause discomfort or sickness if consumed.
- Category 3 Grossly contaminated water. May contain pathogens, sewage, or harmful chemicals.
Classes
- Class 1 Least amount of water absorption and evaporation load. Slow evaporation. Limited area.
- Class 2 Significant amount of water absorption and evaporation load. Wet carpet, cushions, structural components.
- Class 3 Greatest amount of water absorption and evaporation load. Water from overhead, saturated walls and ceilings.
- Class 4 Specialty drying situations. Materials with low porosity holding bound water (hardwood, plaster, masonry).
Details, formula, and sources
(reference page; no compute) IICRC S500-2021 water-loss classes (1 = least amount of water absorption through 4 = greatest, water trapped in materials with low evaporation rates) and categories (1 = sanitary / 2 = significantly contaminated / 3 = grossly contaminated). Original plain-English summary; standard text not reproduced.
IICRC S500-2021 §10.6 (Class) and §10.5 (Category) by section.
IICRC S500-2021 licensed; original summaries free here. Industry overviews free at most restoration-equipment manufacturer (Phoenix, Dri-Eaz, B-Air) sites.
Estimate. AHJ and licensed professional govern.