SOUTH CAROLINA (SC) SEPTIC TANK CONTRACTOR
PRACTICE EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
1. The primary function of a septic tank is to:
A. Store waste permanently
B. Separate solids from wastewater and promote anaerobic digestion
C. Filter effluent before it reaches the soil
D. Aerate wastewater for treatment
Rationale: The septic tank separates solids and scum from liquid
effluent and allows anaerobic bacteria to decompose organic matter.
2. In South Carolina, a septic tank contractor must be licensed by the:
A. Department of Health and Environmental Control (DHEC)
B. Department of Labor, Licensing and Regulation (LLR)
C. Department of Public Safety
D. Board of Sanitation Engineers
Rationale: The SC LLR regulates licensing and certification for septic
tank contractors under state construction codes.
3. The minimum capacity for a septic tank serving a 3-bedroom home
in South Carolina is:
A. 500 gallons
B. 750 gallons
,C. 1,000 gallons
D. 1,250 gallons
Rationale: DHEC guidelines require a minimum 1,000-gallon tank for
up to three bedrooms.
4. The effluent from a properly functioning septic tank should be:
A. Dark brown and odorous
B. Relatively clear with minimal solids
C. Filled with floating grease
D. Completely sterile
Rationale: The tank’s job is to settle and digest solids, producing a
clarified liquid effluent for the drain field.
5. The minimum setback distance from a private well to a septic tank
is:
A. 25 feet
B. 50 feet
C. 75 feet
D. 100 feet
Rationale: SC DHEC requires a 75-foot separation from wells to septic
tanks to prevent groundwater contamination.
6. The drain field is designed to:
A. Disperse effluent into the soil for final treatment
B. Hold solid waste
,C. Pump effluent back to the tank
D. Evaporate effluent into the air
Rationale: The drain field (leach field) allows liquid effluent to
percolate through soil, which filters and treats it.
7. The scum layer in a septic tank is composed mainly of:
A. Sand and grit
B. Fats, oils, and grease
C. Heavy solids
D. Chemical sludge
Rationale: Lighter materials like grease and oils float, forming the
scum layer at the top of the tank.
8. Solids that settle at the bottom of a septic tank form the:
A. Scum layer
B. Floating mat
C. Sludge layer
D. Filtration bed
Rationale: The sludge layer consists of heavy solids that settle and
undergo anaerobic digestion.
9. Which of the following is a sign of septic system failure?
A. Normal grass growth
B. Wet spots or sewage odors above the drain field
C. Occasional toilet gurgle
D. Dry, compact soil
, Rationale: Saturated soil and sewage odors indicate effluent surfacing
due to drain field failure.
10. Which soil type provides the best percolation for a drain field?
A. Sandy loam
B. Clay
C. Silt
D. Bedrock
Rationale: Sandy loam allows good infiltration while retaining some
moisture for microbial treatment.
11. The typical baffle inside a septic tank serves to:
A. Aerate the effluent
B. Prevent solids from entering the outlet
C. Add chemicals to wastewater
D. Support tank structure
Rationale: Baffles direct flow and prevent scum or solids from leaving
the tank to the drain field.
12. Before installing a new septic system, a contractor must:
A. Pour the tank foundation
B. Obtain a permit from SC DHEC
C. Notify the county clerk
D. Register with EPA
Rationale: A DHEC permit ensures site and design approval before
installation begins.
PRACTICE EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
1. The primary function of a septic tank is to:
A. Store waste permanently
B. Separate solids from wastewater and promote anaerobic digestion
C. Filter effluent before it reaches the soil
D. Aerate wastewater for treatment
Rationale: The septic tank separates solids and scum from liquid
effluent and allows anaerobic bacteria to decompose organic matter.
2. In South Carolina, a septic tank contractor must be licensed by the:
A. Department of Health and Environmental Control (DHEC)
B. Department of Labor, Licensing and Regulation (LLR)
C. Department of Public Safety
D. Board of Sanitation Engineers
Rationale: The SC LLR regulates licensing and certification for septic
tank contractors under state construction codes.
3. The minimum capacity for a septic tank serving a 3-bedroom home
in South Carolina is:
A. 500 gallons
B. 750 gallons
,C. 1,000 gallons
D. 1,250 gallons
Rationale: DHEC guidelines require a minimum 1,000-gallon tank for
up to three bedrooms.
4. The effluent from a properly functioning septic tank should be:
A. Dark brown and odorous
B. Relatively clear with minimal solids
C. Filled with floating grease
D. Completely sterile
Rationale: The tank’s job is to settle and digest solids, producing a
clarified liquid effluent for the drain field.
5. The minimum setback distance from a private well to a septic tank
is:
A. 25 feet
B. 50 feet
C. 75 feet
D. 100 feet
Rationale: SC DHEC requires a 75-foot separation from wells to septic
tanks to prevent groundwater contamination.
6. The drain field is designed to:
A. Disperse effluent into the soil for final treatment
B. Hold solid waste
,C. Pump effluent back to the tank
D. Evaporate effluent into the air
Rationale: The drain field (leach field) allows liquid effluent to
percolate through soil, which filters and treats it.
7. The scum layer in a septic tank is composed mainly of:
A. Sand and grit
B. Fats, oils, and grease
C. Heavy solids
D. Chemical sludge
Rationale: Lighter materials like grease and oils float, forming the
scum layer at the top of the tank.
8. Solids that settle at the bottom of a septic tank form the:
A. Scum layer
B. Floating mat
C. Sludge layer
D. Filtration bed
Rationale: The sludge layer consists of heavy solids that settle and
undergo anaerobic digestion.
9. Which of the following is a sign of septic system failure?
A. Normal grass growth
B. Wet spots or sewage odors above the drain field
C. Occasional toilet gurgle
D. Dry, compact soil
, Rationale: Saturated soil and sewage odors indicate effluent surfacing
due to drain field failure.
10. Which soil type provides the best percolation for a drain field?
A. Sandy loam
B. Clay
C. Silt
D. Bedrock
Rationale: Sandy loam allows good infiltration while retaining some
moisture for microbial treatment.
11. The typical baffle inside a septic tank serves to:
A. Aerate the effluent
B. Prevent solids from entering the outlet
C. Add chemicals to wastewater
D. Support tank structure
Rationale: Baffles direct flow and prevent scum or solids from leaving
the tank to the drain field.
12. Before installing a new septic system, a contractor must:
A. Pour the tank foundation
B. Obtain a permit from SC DHEC
C. Notify the county clerk
D. Register with EPA
Rationale: A DHEC permit ensures site and design approval before
installation begins.
