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Water Damage Categories


The complexity and cost of the cleanup will be based on these industry-defined standards of water damage. 

Category 1 Water Damage

Category 1 water originates from a sanitary water source and does not pose substantial risk from dermal (skin), ingestion (drinking), or inhalation exposure.
Examples of Category 1 water can include:
Broken water supply lines, tub or sink overflows without contaminants, appliance malfunctions involving water-supply lines, melting ice or snow, falling rainwater that does not contact any other surface, broken toilet cisterns.

Category 2 Water Damage

Category 2 water contains significant contamination and has the potential to cause discomfort or sickness if contacted or consumed by humans.

Category 2 water can contain potentially unsafe levels of microorganisms or nutrients for microorganisms, as well as organic or inorganic matter (chemical or biological).

Examples of Category 2 water can include, but are not limited to: Discharge from dishwashers or washing machines, overflows from washing machines, overflows from toilet bowls on the room side of the trap with some urine, but no feces, seepage due to hydrostatic pressure, water flowing through a hole in a roof, passing through the ceiling insulation and building materials.

Cleanliness of Category 1 or 2 water can potentially deteriorate for many reasons, including, but not limited to: contact with building materials, systems, and contents or mixing with soils and other contaminants.

Factors that influence the potential organic and inorganic load in a structure include the age and history of the structure, previous water losses, general housekeeping, the type of use of the structure, and elevated temperatures or elapsed time since the water intrusion. These can move to advanced categories.


Category 3 Water Damage

Category 3 water is grossly contaminated and can contain pathogenic, toxigenic or other harmful agents.

Examples of Category 3 water can include, but are not limited to:
Sewage, waste line backflows that originate from beyond any trap regardless of visible colour or content, ground surface water and rising water from rivers or streams, all forms of flooding from seawater, other contaminated water entering or affecting the indoor environment as: wind-driven rain from hurricanes, tropical storms, weather-related events, above sources carrying silt, organic matter, pesticides, heavy metals, regulated materials, or toxic organic substances. After remediation, an IEP (indoor environmental professional) may be necessary to assess contamination levels, evaluate and determine if safe to occupy.

Classes of Water Intrusion

Classes of water loss refer to the amount of water and the anticipated rate of evaporation based on the amount and type of wet materials in a property.
There are four classes of water loss:

Water Drops

Class 1: Slow Rate of Evaporation

A class one water loss affects only part of a room with low-permeance or low-porosity materials such as particleboard, plywood, structural wood, vinyl composition tile, and concrete.


Class 2: Fast Rate of Evaporation

Class two water losses affect the whole room and materials such as carpet and cushion. Seepage of water up walls is less than 24 inches, and moisture remains in structural materials. 

Image by Matt Hoffman

Class 3: Fastest Rate of Evaporation

Class three water losses typically come from overhead, saturating insulation, ceilings, walls, carpet, cushion, and subfloor in virtually the entire area.


Class 4: Specialty Drying Situations

Specialty drying situations involve wet materials with very low permeance or low porosity. Examples include hardwood, plaster, brick, concrete, stone, sub-floors, and crawlspaces.

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