IICRC WRT PROFESSIONAL
CERTIFICATION EXAM QUESTIONS
AND ANSWERS
1. According to the IICRC S500, what is the definition of Category 3 water?
A. Water that originates from a sanitary water source and does not pose substantial risk.
B. Water that is grossly contaminated and can contain pathogenic, toxigenic, or other
harmful agents.
C. Water that contains significant contamination and has the potential to cause discomfort
or sickness.
D. Water that has remained stagnant for more than 48 hours but was originally clean.
Answer: B
Conceptual Explanation: Category 3 water is grossly contaminated and can contain
pathogens and toxins. Examples include sewage, rising floodwater from rivers, and wind-
driven rain from hurricanes.
2. What is the specific term for the weight of water vapor in the air, measured in grains per
pound (gpp)?
A. Relative Humidity
,B. Dew Point
C. Vapor Pressure
D. Humidity Ratio
Answer: D
Conceptual Explanation: Humidity ratio (often called specific humidity) is the weight of
water vapor per unit weight of dry air, typically expressed in grains per pound (gpp).
3. Which class of water intrusion involves the largest volume of water, where moisture is
present in low-evaporation materials like concrete or crawlspaces?
A. Class 1
B. Class 2
C. Class 4
D. Class 3
Answer: C
Conceptual Explanation: Class 4 water intrusions involve significant amounts of water
that have saturated low-evaporation materials like plaster, wood, stone, or concrete,
requiring specialized drying methods.
4. At what moisture content (MC) percentage is the ‘fiber saturation point’ of wood typically
reached?
A. approx. 30%
, B. 20% to 25%
C. 10% to 15%
D. approx. 50%
Answer: A
Conceptual Explanation: The fiber saturation point is the point at which the cell walls are
completely saturated but the cell cavities are empty, typically around 30% MC for most
wood species.
5. When using an LGR (Low Grain Refrigerant) dehumidifier, at what GPP level do they
generally continue to remove water effectively compared to conventional units?
A. Below 55 GPP
B. Below 34 GPP
C. Only above 60 GPP
D. Between 80 and 100 GPP
Answer: B
Conceptual Explanation: LGR dehumidifiers are designed to continue removing water
vapor even when the humidity ratio drops below 34-40 GPP, whereas conventional units
lose efficiency below 55-60 GPP.
6. What is the primary purpose of a ‘dry standard’ in water restoration?
A. To determine the current moisture content of a wet material.
CERTIFICATION EXAM QUESTIONS
AND ANSWERS
1. According to the IICRC S500, what is the definition of Category 3 water?
A. Water that originates from a sanitary water source and does not pose substantial risk.
B. Water that is grossly contaminated and can contain pathogenic, toxigenic, or other
harmful agents.
C. Water that contains significant contamination and has the potential to cause discomfort
or sickness.
D. Water that has remained stagnant for more than 48 hours but was originally clean.
Answer: B
Conceptual Explanation: Category 3 water is grossly contaminated and can contain
pathogens and toxins. Examples include sewage, rising floodwater from rivers, and wind-
driven rain from hurricanes.
2. What is the specific term for the weight of water vapor in the air, measured in grains per
pound (gpp)?
A. Relative Humidity
,B. Dew Point
C. Vapor Pressure
D. Humidity Ratio
Answer: D
Conceptual Explanation: Humidity ratio (often called specific humidity) is the weight of
water vapor per unit weight of dry air, typically expressed in grains per pound (gpp).
3. Which class of water intrusion involves the largest volume of water, where moisture is
present in low-evaporation materials like concrete or crawlspaces?
A. Class 1
B. Class 2
C. Class 4
D. Class 3
Answer: C
Conceptual Explanation: Class 4 water intrusions involve significant amounts of water
that have saturated low-evaporation materials like plaster, wood, stone, or concrete,
requiring specialized drying methods.
4. At what moisture content (MC) percentage is the ‘fiber saturation point’ of wood typically
reached?
A. approx. 30%
, B. 20% to 25%
C. 10% to 15%
D. approx. 50%
Answer: A
Conceptual Explanation: The fiber saturation point is the point at which the cell walls are
completely saturated but the cell cavities are empty, typically around 30% MC for most
wood species.
5. When using an LGR (Low Grain Refrigerant) dehumidifier, at what GPP level do they
generally continue to remove water effectively compared to conventional units?
A. Below 55 GPP
B. Below 34 GPP
C. Only above 60 GPP
D. Between 80 and 100 GPP
Answer: B
Conceptual Explanation: LGR dehumidifiers are designed to continue removing water
vapor even when the humidity ratio drops below 34-40 GPP, whereas conventional units
lose efficiency below 55-60 GPP.
6. What is the primary purpose of a ‘dry standard’ in water restoration?
A. To determine the current moisture content of a wet material.
