Water damage is classified into one of the following classes:
Class 1 water damage (least amount of water, absorption and evaporation): Water losses that affect only part of a room or area, or larger areas containing materials that have absorbed minimal moisture. Little or no wet carpet and/or cushion are present.
Class 2 water damage (large amount of water, absorption and evaporation): Water losses that affect at least an entire room or carpet and cushion(pad). Water has wicked up walls less than 24”. There is moisture remaining in structural materials (e.g., plywood, particleboard, structural wood, concrete).
Class 3 water damage (greatest amount of water, absorption and evaporation): Water wicked up over 24″, or water may have come from overhead affecting ceilings, walls, insulation, carpet, cushion and sub-floor. The entire area are saturated.
Class 4 water damage (specialty drying situations): These consist of wet materials with very low permeance/porosity (hardwood, plaster, brick, concrete, stone). Typically, there are deep pockets of saturation, which requires very low specific humidity.
Water, under the IICRC’s S-500 Standard and Reference Guide for Professional Water Damage Restoration, has been broken off into three categories. These categories are based upon the level of contamination present, or presumed present, in the source water.
Category 1 is water from a clean or sanitary source. Previously known as clear water or clean water, this descriptor has since been removed to reduce confusion. These can include water from broken clean water supply lines; clean water from toilet tank or bowl; faucets; and bottled water. Although the source may be from a clean source, category 1 water can quickly degrade into category 2 or 3 depending upon such factors as time, temperature, and contact with contaminants.
Category 2 is water with some level of contaminants that could cause discomfort or illness if ingested. Previously known as grey water, this descriptor has since been removed to avoid confusion. Sources for category 2 water may include washing machine overflow; toilet overflow with some urine, but no feces; and dishwasher overflow. Category 2 water can quickly degrade into category 3 depending upon such factors as time, temperature, and contact with contaminants.
Category 3 water is grossly unsanitary, and could cause severe illness or death if ingested. Previously known as black water or black water, this descriptor has since been removed to avoid confusion. Sources for category 3 water include, but are not limited to, sewage; flooding from rivers or streams; wind-driven rain, water from beyond the toilet trap; water from the toilet bowl with feces; and standing water that has begun to support microbial growth.