Category 1: Category 1 water originates from a sanitary water source and does not pose
substantial risk from dermal, ingestion, or inhalation exposure. Examples of Category 1 water
sources can include, but are not limited to: broken water supply lines; tub or sink overflows with no
contaminants; appliance malfunctions involving water-supply lines; melting ice or snow; falling
rainwater; broken toilet tanks, and toilet bowls that do not contain contaminants or additives.
Category 1 water can deteriorate to Category 2 or 3. Category 1 water that flows into an uncontaminated building does not constitute an immediate change in the category. However,
Category 1 water that flows into a contaminated building can constitute an immediate change in
the category. Once microorganisms become wet from the water intrusion, depending upon the
length of time that they remain wet and the temperature, they can begin to grow in numbers and
can change the category of the water. Odors can indicate that Category 1 water has deteriorated.
Category 2: 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 other
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; broken aquariums and punctured water beds.
Category 2 water can deteriorate to Category 3. Once microorganisms become wet from the water
intrusion, depending upon the length of time that they remain wet and the temperature, they can
begin to grow in numbers and can change the category of the water.
Category 3: Category 3 water is grossly contaminated and can contain pathogenic, toxigenic or
other harmful agents and can cause significant adverse reactions to humans if contacted or
consumed.
Examples of Category 3 water can include, but are not limited to: sewage; wasteline
backflows that originate from beyond any trap regardless of visible content or color; all forms of
flooding from seawater; rising water from rivers or streams; and other contaminated water entering
or affecting the indoor environment, such as wind-driven rain from hurricanes, tropical storms, or
other weather-related events. Category 3 water can carry trace levels of regulated or hazardous
materials (e.g., pesticides, or toxic organic substances).
https://www.iicrc.org/page/SANSIIICRCS500