==============================
EXAMINATION PAPER
EXAM TITLE: South Carolina Septic Tank Contractor Licensing Exam
Questions | 100% Correct Answers with Detailed Rationales (2026/2027
Edition)
South Carolina Onsite Wastewater Systems Contractor Licensing Examination
==============================
SECTION 1: South Carolina DHEC Regulations and Permitting
Question 1
Under South Carolina DHEC Regulation 61-56, what is the minimum horizontal setback
distance required between a septic tank and a private water well?
A. 25 feet
B. 50 feet
C. 75 feet
D. 100 feet
Correct Answer: B
Rationale: South Carolina DHEC Regulation 61-56 requires a minimum horizontal
setback of 50 feet between a septic tank and a private water well. This distance is
established to prevent potential contamination of potable water supplies from septic
,system effluent. A 25-foot setback (A) is insufficient and would violate state regulations.
A 75-foot setback (C) and 100-foot setback (D) exceed the minimum requirement but
are not the mandated standard.
Question 2
A contractor is installing a conventional septic system in Beaufort County, South
Carolina. According to DHEC Regulation 61-56, which soil texture classification is
generally considered unsuitable for a conventional drain field without significant
modification or use of an alternative system?
A. Sandy loam
B. Loamy sand
C. Clay
D. Silt loam
Correct Answer: C
Rationale: Clay soils are generally considered unsuitable for conventional drain fields in
South Carolina due to their extremely slow percolation rates, poor drainage
characteristics, and tendency to become waterlogged. Clay soils typically have
percolation rates slower than 60 minutes per inch, which exceeds the acceptable range
for conventional systems. Sandy loam (A), loamy sand (B), and silt loam (D) are
generally suitable soil textures for conventional drain fields when percolation rates are
within acceptable limits.
,Question 3
Under South Carolina DHEC Regulation 61-56, what is the maximum allowable depth for
a conventional septic tank?
A. 60 inches
B. 72 inches
C. 84 inches
D. 96 inches
Correct Answer: C
Rationale: South Carolina DHEC Regulation 61-56 specifies that the maximum allowable
depth for a conventional septic tank is 84 inches (7 feet). This depth limitation ensures
adequate access for maintenance, pumping, and inspection while maintaining structural
integrity and proper wastewater treatment function. Depths exceeding 84 inches (D) are
prohibited due to safety concerns and accessibility issues. Options A and B are within
the allowable range but do not represent the maximum.
Question 4
A contractor submits a permit application for a new septic system installation in Horry
County. According to South Carolina DHEC requirements, how long is a site evaluation
(soil test) considered valid for permitting purposes?
, A. 6 months
B. 12 months
C. 24 months
D. 36 months
Correct Answer: C
Rationale: In South Carolina, a site evaluation (including percolation tests and deep hole
tests) is considered valid for 24 months from the date of completion for permitting
purposes. This timeframe ensures that site conditions have not significantly changed
due to weather, erosion, or land disturbance. A 6-month validity (A) and 12-month
validity (B) are too restrictive and do not reflect current DHEC regulations. A 36-month
validity (D) would be excessive and could allow for significant site changes.
Question 5
Under South Carolina DHEC Regulation 61-56, what is the minimum required septic tank
capacity for a single-family residence with three bedrooms?
A. 750 gallons
B. 900 gallons
C. 1,000 gallons
D. 1,250 gallons
Correct Answer: C
EXAMINATION PAPER
EXAM TITLE: South Carolina Septic Tank Contractor Licensing Exam
Questions | 100% Correct Answers with Detailed Rationales (2026/2027
Edition)
South Carolina Onsite Wastewater Systems Contractor Licensing Examination
==============================
SECTION 1: South Carolina DHEC Regulations and Permitting
Question 1
Under South Carolina DHEC Regulation 61-56, what is the minimum horizontal setback
distance required between a septic tank and a private water well?
A. 25 feet
B. 50 feet
C. 75 feet
D. 100 feet
Correct Answer: B
Rationale: South Carolina DHEC Regulation 61-56 requires a minimum horizontal
setback of 50 feet between a septic tank and a private water well. This distance is
established to prevent potential contamination of potable water supplies from septic
,system effluent. A 25-foot setback (A) is insufficient and would violate state regulations.
A 75-foot setback (C) and 100-foot setback (D) exceed the minimum requirement but
are not the mandated standard.
Question 2
A contractor is installing a conventional septic system in Beaufort County, South
Carolina. According to DHEC Regulation 61-56, which soil texture classification is
generally considered unsuitable for a conventional drain field without significant
modification or use of an alternative system?
A. Sandy loam
B. Loamy sand
C. Clay
D. Silt loam
Correct Answer: C
Rationale: Clay soils are generally considered unsuitable for conventional drain fields in
South Carolina due to their extremely slow percolation rates, poor drainage
characteristics, and tendency to become waterlogged. Clay soils typically have
percolation rates slower than 60 minutes per inch, which exceeds the acceptable range
for conventional systems. Sandy loam (A), loamy sand (B), and silt loam (D) are
generally suitable soil textures for conventional drain fields when percolation rates are
within acceptable limits.
,Question 3
Under South Carolina DHEC Regulation 61-56, what is the maximum allowable depth for
a conventional septic tank?
A. 60 inches
B. 72 inches
C. 84 inches
D. 96 inches
Correct Answer: C
Rationale: South Carolina DHEC Regulation 61-56 specifies that the maximum allowable
depth for a conventional septic tank is 84 inches (7 feet). This depth limitation ensures
adequate access for maintenance, pumping, and inspection while maintaining structural
integrity and proper wastewater treatment function. Depths exceeding 84 inches (D) are
prohibited due to safety concerns and accessibility issues. Options A and B are within
the allowable range but do not represent the maximum.
Question 4
A contractor submits a permit application for a new septic system installation in Horry
County. According to South Carolina DHEC requirements, how long is a site evaluation
(soil test) considered valid for permitting purposes?
, A. 6 months
B. 12 months
C. 24 months
D. 36 months
Correct Answer: C
Rationale: In South Carolina, a site evaluation (including percolation tests and deep hole
tests) is considered valid for 24 months from the date of completion for permitting
purposes. This timeframe ensures that site conditions have not significantly changed
due to weather, erosion, or land disturbance. A 6-month validity (A) and 12-month
validity (B) are too restrictive and do not reflect current DHEC regulations. A 36-month
validity (D) would be excessive and could allow for significant site changes.
Question 5
Under South Carolina DHEC Regulation 61-56, what is the minimum required septic tank
capacity for a single-family residence with three bedrooms?
A. 750 gallons
B. 900 gallons
C. 1,000 gallons
D. 1,250 gallons
Correct Answer: C
