Alabama Onsite Wastewater Installer
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. The primary purpose of an onsite wastewater treatment system is to:
A. Store wastewater indefinitely
B. Transport wastewater to a municipal plant
C. Treat and safely dispose of wastewater generated at an individual
property
D. Increase groundwater flow near a home
Answer: C. Treat and safely dispose of wastewater generated at an
individual property
Rationale: Onsite wastewater systems are designed to collect, treat, and
dispose of wastewater from individual properties where centralized sewer
service is unavailable.
, 2. Which component of a conventional onsite wastewater system
provides the initial separation of solids and scum from wastewater?
A. Distribution box
B. Septic tank
C. Drainfield
D. Pump chamber
Answer: B. Septic tank
Rationale: The septic tank allows solids to settle as sludge, grease and
scum to float, and partially clarified effluent to continue to treatment and
disposal areas.
3. Soil evaluation for an onsite wastewater system is primarily performed
to determine:
A. Property tax value
B. Soil color only
C. Suitability for wastewater absorption and treatment
D. The age of the soil
Answer: C. Suitability for wastewater absorption and treatment
Rationale: Soil characteristics such as texture, structure, permeability, and
limiting conditions determine whether wastewater can be properly treated
and dispersed.
, 4. A septic tank should generally be installed:
A. Above the roof elevation of the home
B. In an accessible location for inspection and pumping
C. Directly under the drainfield
D. Inside the residence
Answer: B. In an accessible location for inspection and pumping
Rationale: Proper access allows routine inspection, maintenance, and
pumping without damaging the system or property.
5. The purpose of a septic tank outlet filter is to:
A. Increase wastewater temperature
B. Prevent large solids from leaving the tank
C. Eliminate all bacteria
D. Replace the drainfield
Answer: B. Prevent large solids from leaving the tank
Rationale: Outlet filters help reduce solids discharge into the absorption
field, protecting the drainfield from clogging.
6. Which material is commonly used for septic tank inlet and outlet
piping?
, A. Flexible garden hose
B. Approved PVC pipe
C. Wooden pipe
D. Copper tubing
Answer: B. Approved PVC pipe
Rationale: Approved PVC piping provides durability, corrosion resistance,
and proper hydraulic performance in wastewater systems.
7. The drainfield’s main function is to:
A. Store untreated sewage
B. Pump wastewater back into the septic tank
C. Distribute and treat effluent through soil
D. Remove grease mechanically
Answer: C. Distribute and treat effluent through soil
Rationale: The drainfield disperses septic tank effluent into soil where
biological and physical treatment occurs.
8. Excessive vehicle traffic over a drainfield may:
A. Improve soil treatment
B. Increase system capacity
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. The primary purpose of an onsite wastewater treatment system is to:
A. Store wastewater indefinitely
B. Transport wastewater to a municipal plant
C. Treat and safely dispose of wastewater generated at an individual
property
D. Increase groundwater flow near a home
Answer: C. Treat and safely dispose of wastewater generated at an
individual property
Rationale: Onsite wastewater systems are designed to collect, treat, and
dispose of wastewater from individual properties where centralized sewer
service is unavailable.
, 2. Which component of a conventional onsite wastewater system
provides the initial separation of solids and scum from wastewater?
A. Distribution box
B. Septic tank
C. Drainfield
D. Pump chamber
Answer: B. Septic tank
Rationale: The septic tank allows solids to settle as sludge, grease and
scum to float, and partially clarified effluent to continue to treatment and
disposal areas.
3. Soil evaluation for an onsite wastewater system is primarily performed
to determine:
A. Property tax value
B. Soil color only
C. Suitability for wastewater absorption and treatment
D. The age of the soil
Answer: C. Suitability for wastewater absorption and treatment
Rationale: Soil characteristics such as texture, structure, permeability, and
limiting conditions determine whether wastewater can be properly treated
and dispersed.
, 4. A septic tank should generally be installed:
A. Above the roof elevation of the home
B. In an accessible location for inspection and pumping
C. Directly under the drainfield
D. Inside the residence
Answer: B. In an accessible location for inspection and pumping
Rationale: Proper access allows routine inspection, maintenance, and
pumping without damaging the system or property.
5. The purpose of a septic tank outlet filter is to:
A. Increase wastewater temperature
B. Prevent large solids from leaving the tank
C. Eliminate all bacteria
D. Replace the drainfield
Answer: B. Prevent large solids from leaving the tank
Rationale: Outlet filters help reduce solids discharge into the absorption
field, protecting the drainfield from clogging.
6. Which material is commonly used for septic tank inlet and outlet
piping?
, A. Flexible garden hose
B. Approved PVC pipe
C. Wooden pipe
D. Copper tubing
Answer: B. Approved PVC pipe
Rationale: Approved PVC piping provides durability, corrosion resistance,
and proper hydraulic performance in wastewater systems.
7. The drainfield’s main function is to:
A. Store untreated sewage
B. Pump wastewater back into the septic tank
C. Distribute and treat effluent through soil
D. Remove grease mechanically
Answer: C. Distribute and treat effluent through soil
Rationale: The drainfield disperses septic tank effluent into soil where
biological and physical treatment occurs.
8. Excessive vehicle traffic over a drainfield may:
A. Improve soil treatment
B. Increase system capacity
