AR SS – Sewer & Sanitation Contractor
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary function of a sewer main?
A. Supply potable water
B. Release sewer gases
C. Transport stormwater only
D. Transport collected wastewater to treatment facilities
Rationale: Sewer mains carry wastewater from service lines to treatment
plants.
2. Which type of pipe is most commonly used for gravity sewer lines?
A. Copper
B. PVC SDR-35
C. Aluminum
D. Galvanized steel
Rationale: SDR-35 PVC is standard for gravity sewer systems due to
corrosion resistance and cost efficiency.
3. Minimum slope for a 6-inch sewer lateral is typically:
A. 0.5%
B. 1%
C. 2%
D. 5%
,Rationale: Many codes require 1% slope for 6-inch laterals to maintain
flow velocity.
4. A manhole is required at changes in direction greater than:
A. 10°
B. 15°
C. 30°
D. 45°
Rationale: Bends above 45° generally require manholes for access and
cleaning.
5. What device prevents sewer gases from entering buildings?
A. Cleanout
B. P-trap
C. Air admittance valve
D. Backflow damper
Rationale: P-traps hold water that blocks sewer gases.
6. Which test verifies watertightness of a new sewer line?
A. Dye test
B. Flow test
C. Low-pressure air test
D. Sound test
Rationale: Low-pressure air testing is a standard method for checking
sewer pipe integrity.
7. The purpose of a cleanout is to:
A. Vent sewer gases
B. Provide access for maintenance
C. Store wastewater
D. Increase pipe pressure
Rationale: Cleanouts allow rodding and inspection of sewer laterals.
8. Infiltration in sewer systems is caused by:
, A. User demand
B. Groundwater entering defective pipes
C. Pressure surges
D. Solid blockages
Rationale: Infiltration refers to groundwater leaking into sewer systems.
9. Exfiltration refers to:
A. Odor release
B. Air entering pipes
C. Wastewater backing up into houses
D. Wastewater leaking out of sewer pipes
Rationale: Exfiltration is wastewater escaping the sewer system.
10. What is the main danger of entering a confined sewer space?
A. High humidity
B. Toxic or oxygen-deficient atmosphere
C. Low light
D. Noise
Rationale: Confined sewers often contain hazardous gases like H₂S and
low oxygen.
11. Hydrogen sulfide gas smells like:
A. Ammonia
B. Rotten apples
C. Rotten eggs
D. Chlorine
Rationale: H₂S has a characteristic rotten-egg odor.
12. Before entering a manhole, testing must be performed for:
A. Viscosity
B. pH
C. Oxygen, toxic gases, and flammables
D. Noise
Rationale: Atmospheric testing is legally required for confined spaces.
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary function of a sewer main?
A. Supply potable water
B. Release sewer gases
C. Transport stormwater only
D. Transport collected wastewater to treatment facilities
Rationale: Sewer mains carry wastewater from service lines to treatment
plants.
2. Which type of pipe is most commonly used for gravity sewer lines?
A. Copper
B. PVC SDR-35
C. Aluminum
D. Galvanized steel
Rationale: SDR-35 PVC is standard for gravity sewer systems due to
corrosion resistance and cost efficiency.
3. Minimum slope for a 6-inch sewer lateral is typically:
A. 0.5%
B. 1%
C. 2%
D. 5%
,Rationale: Many codes require 1% slope for 6-inch laterals to maintain
flow velocity.
4. A manhole is required at changes in direction greater than:
A. 10°
B. 15°
C. 30°
D. 45°
Rationale: Bends above 45° generally require manholes for access and
cleaning.
5. What device prevents sewer gases from entering buildings?
A. Cleanout
B. P-trap
C. Air admittance valve
D. Backflow damper
Rationale: P-traps hold water that blocks sewer gases.
6. Which test verifies watertightness of a new sewer line?
A. Dye test
B. Flow test
C. Low-pressure air test
D. Sound test
Rationale: Low-pressure air testing is a standard method for checking
sewer pipe integrity.
7. The purpose of a cleanout is to:
A. Vent sewer gases
B. Provide access for maintenance
C. Store wastewater
D. Increase pipe pressure
Rationale: Cleanouts allow rodding and inspection of sewer laterals.
8. Infiltration in sewer systems is caused by:
, A. User demand
B. Groundwater entering defective pipes
C. Pressure surges
D. Solid blockages
Rationale: Infiltration refers to groundwater leaking into sewer systems.
9. Exfiltration refers to:
A. Odor release
B. Air entering pipes
C. Wastewater backing up into houses
D. Wastewater leaking out of sewer pipes
Rationale: Exfiltration is wastewater escaping the sewer system.
10. What is the main danger of entering a confined sewer space?
A. High humidity
B. Toxic or oxygen-deficient atmosphere
C. Low light
D. Noise
Rationale: Confined sewers often contain hazardous gases like H₂S and
low oxygen.
11. Hydrogen sulfide gas smells like:
A. Ammonia
B. Rotten apples
C. Rotten eggs
D. Chlorine
Rationale: H₂S has a characteristic rotten-egg odor.
12. Before entering a manhole, testing must be performed for:
A. Viscosity
B. pH
C. Oxygen, toxic gases, and flammables
D. Noise
Rationale: Atmospheric testing is legally required for confined spaces.
