TENNESSEE SEPTIC SYSTEM INSTALLER
LICENSING EXAMINATION |QUESTIONS AND
ANSWERS |2026|2027 UPDATES| WITH
COMPLETE SOLUTIONS.
Introduction
This practice question bank is designed to assist candidates preparing for the
Tennessee Septic System Installer Licensing Examination. The examination is
administered by the Tennessee Department of Environment and Conservation
(TDEC), Division of Water Resources. To obtain a Conventional SSDS Installer
Permit, applicants must achieve a passing score of 70% or above on the written
examination.
The following questions cover essential exam domains including system design
and components, soil and site evaluation, installation standards, Tennessee state
regulations, and workplace safety. Each question is followed by the correct answer
and a rationale explaining the underlying principle. The format follows the
multiple-choice structure used on the actual licensing examination.
Questions 1–50: System Components and Design
1. What is the primary purpose of a septic tank in a conventional subsurface
sewage disposal system?
A. To sterilize all wastewater before discharge
B. To separate solids from wastewater and begin anaerobic treatment
C. To aerate effluent for rapid decomposition
D. To store effluent indefinitely until pumped
B. To separate solids from wastewater and begin anaerobic treatment
Rationale: The septic tank provides primary treatment by allowing heavier solids
to settle as sludge and lighter materials to float as scum, while anaerobic bacteria
,partially decompose organic matter. The clarified effluent then flows to the drain
field for final treatment.
2. Which component of a septic tank prevents floating scum from exiting into
the drain field?
A. Distribution box
B. Effluent filter
C. Baffle
D. Riser
C. Baffle
Rationale: The baffle (or "tee") at the tank outlet creates a barrier that holds back
the floating scum layer, ensuring only relatively clear effluent enters the
distribution system. This prevents solids from clogging the drain field.
3. What is the function of a distribution box (D-box) in a conventional septic
system?
A. To collect and store solids before pumping
B. To evenly distribute effluent to each drain field lateral
C. To aerate the effluent before soil absorption
D. To remove nitrogen and phosphorus from wastewater
B. To evenly distribute effluent to each drain field lateral
Rationale: The distribution box receives effluent from the septic tank and divides it
equally among the drain field trenches. Unequal distribution can overload one
portion of the field, causing premature failure.
4. What is the purpose of an effluent filter installed at the septic tank outlet?
A. To disinfect effluent with chlorine
B. To prevent suspended solids from leaving the tank
C. To increase the flow rate to the drain field
D. To neutralize household chemicals
,B. To prevent suspended solids from leaving the tank
Rationale: Effluent filters trap fine solids that escape the tank's settling process,
reducing the risk of drain field clogging. These filters require periodic cleaning by
the homeowner or service provider.
5. The invert of a septic tank outlet must be positioned:
A. Higher than the inlet
B. Lower than the inlet
C. At the exact same elevation as the inlet
D. Above the tank's high-water alarm
B. Lower than the inlet
Rationale: A slightly lower outlet invert ensures gravity flow through the tank and
prevents wastewater from backing up into the building. The elevation difference
also helps maintain proper liquid level within the tank.
6. Which type of bacteria is primarily responsible for decomposition in a
septic tank?
A. Aerobic bacteria
B. Anaerobic bacteria
C. Photosynthetic bacteria
D. Denitrifying bacteria
B. Anaerobic bacteria
Rationale: Septic tanks operate in an oxygen-limited (anaerobic) environment.
Anaerobic bacteria break down organic solids without oxygen, producing gases
such as methane and hydrogen sulfide.
7. What is the minimum liquid capacity typically required for a septic tank
serving a three-bedroom home in Tennessee?
A. 500 gallons
B. 750 gallons
, C. 1,000 gallons
D. 1,500 gallons
C. 1,000 gallons
Rationale: Regulatory guidelines generally require a minimum 1,000-gallon tank
for a standard three-bedroom residence. Tank sizing increases with the number of
bedrooms to provide adequate retention time for solids settling.
8. What is the purpose of a riser installed on a septic tank?
A. To increase the tank's treatment capacity
B. To provide surface-level access for inspection and pumping
C. To vent gases above the roofline
D. To distribute effluent more evenly
B. To provide surface-level access for inspection and pumping
Rationale: Risers extend from the tank lid to ground level, eliminating the need to
excavate when pumping or inspecting the tank. This facilitates routine maintenance
and reduces the risk of lid damage.
9. In a pumped (dosing) system, what is the primary function of the float
switch?
A. To measure effluent quality
B. To activate the pump when effluent reaches a set level
C. To prevent backflow into the tank
D. To alarm when the tank is full
B. To activate the pump when effluent reaches a set level
Rationale: Float switches detect the effluent level in the pump tank and turn the
pump on and off at predetermined set points. Proper float adjustment ensures
consistent dosing volumes to the drain field.
10. What is the main purpose of a pump tank alarm in a pressure-dosed septic
system?
LICENSING EXAMINATION |QUESTIONS AND
ANSWERS |2026|2027 UPDATES| WITH
COMPLETE SOLUTIONS.
Introduction
This practice question bank is designed to assist candidates preparing for the
Tennessee Septic System Installer Licensing Examination. The examination is
administered by the Tennessee Department of Environment and Conservation
(TDEC), Division of Water Resources. To obtain a Conventional SSDS Installer
Permit, applicants must achieve a passing score of 70% or above on the written
examination.
The following questions cover essential exam domains including system design
and components, soil and site evaluation, installation standards, Tennessee state
regulations, and workplace safety. Each question is followed by the correct answer
and a rationale explaining the underlying principle. The format follows the
multiple-choice structure used on the actual licensing examination.
Questions 1–50: System Components and Design
1. What is the primary purpose of a septic tank in a conventional subsurface
sewage disposal system?
A. To sterilize all wastewater before discharge
B. To separate solids from wastewater and begin anaerobic treatment
C. To aerate effluent for rapid decomposition
D. To store effluent indefinitely until pumped
B. To separate solids from wastewater and begin anaerobic treatment
Rationale: The septic tank provides primary treatment by allowing heavier solids
to settle as sludge and lighter materials to float as scum, while anaerobic bacteria
,partially decompose organic matter. The clarified effluent then flows to the drain
field for final treatment.
2. Which component of a septic tank prevents floating scum from exiting into
the drain field?
A. Distribution box
B. Effluent filter
C. Baffle
D. Riser
C. Baffle
Rationale: The baffle (or "tee") at the tank outlet creates a barrier that holds back
the floating scum layer, ensuring only relatively clear effluent enters the
distribution system. This prevents solids from clogging the drain field.
3. What is the function of a distribution box (D-box) in a conventional septic
system?
A. To collect and store solids before pumping
B. To evenly distribute effluent to each drain field lateral
C. To aerate the effluent before soil absorption
D. To remove nitrogen and phosphorus from wastewater
B. To evenly distribute effluent to each drain field lateral
Rationale: The distribution box receives effluent from the septic tank and divides it
equally among the drain field trenches. Unequal distribution can overload one
portion of the field, causing premature failure.
4. What is the purpose of an effluent filter installed at the septic tank outlet?
A. To disinfect effluent with chlorine
B. To prevent suspended solids from leaving the tank
C. To increase the flow rate to the drain field
D. To neutralize household chemicals
,B. To prevent suspended solids from leaving the tank
Rationale: Effluent filters trap fine solids that escape the tank's settling process,
reducing the risk of drain field clogging. These filters require periodic cleaning by
the homeowner or service provider.
5. The invert of a septic tank outlet must be positioned:
A. Higher than the inlet
B. Lower than the inlet
C. At the exact same elevation as the inlet
D. Above the tank's high-water alarm
B. Lower than the inlet
Rationale: A slightly lower outlet invert ensures gravity flow through the tank and
prevents wastewater from backing up into the building. The elevation difference
also helps maintain proper liquid level within the tank.
6. Which type of bacteria is primarily responsible for decomposition in a
septic tank?
A. Aerobic bacteria
B. Anaerobic bacteria
C. Photosynthetic bacteria
D. Denitrifying bacteria
B. Anaerobic bacteria
Rationale: Septic tanks operate in an oxygen-limited (anaerobic) environment.
Anaerobic bacteria break down organic solids without oxygen, producing gases
such as methane and hydrogen sulfide.
7. What is the minimum liquid capacity typically required for a septic tank
serving a three-bedroom home in Tennessee?
A. 500 gallons
B. 750 gallons
, C. 1,000 gallons
D. 1,500 gallons
C. 1,000 gallons
Rationale: Regulatory guidelines generally require a minimum 1,000-gallon tank
for a standard three-bedroom residence. Tank sizing increases with the number of
bedrooms to provide adequate retention time for solids settling.
8. What is the purpose of a riser installed on a septic tank?
A. To increase the tank's treatment capacity
B. To provide surface-level access for inspection and pumping
C. To vent gases above the roofline
D. To distribute effluent more evenly
B. To provide surface-level access for inspection and pumping
Rationale: Risers extend from the tank lid to ground level, eliminating the need to
excavate when pumping or inspecting the tank. This facilitates routine maintenance
and reduces the risk of lid damage.
9. In a pumped (dosing) system, what is the primary function of the float
switch?
A. To measure effluent quality
B. To activate the pump when effluent reaches a set level
C. To prevent backflow into the tank
D. To alarm when the tank is full
B. To activate the pump when effluent reaches a set level
Rationale: Float switches detect the effluent level in the pump tank and turn the
pump on and off at predetermined set points. Proper float adjustment ensures
consistent dosing volumes to the drain field.
10. What is the main purpose of a pump tank alarm in a pressure-dosed septic
system?
