Onsite Wastewater System Installer Licensing
Exam Prep | Questions And Answers With
Verified Rationales | 2026/27 Qs & Ans | Digital
Pdf Download
1. What is the primary purpose of an onsite wastewater system?
A. Increase groundwater pollution
B. Treat and safely dispose of wastewater on the property
C. Store untreated sewage indefinitely
D. Increase surface runoff
Answer: B
Rationale: Onsite systems treat and dispose of wastewater at or near the
point of generation.
2. Which system component distributes effluent into the soil?
A. Distribution box
B. Aeration blower
C. Chlorine tank
D. Grease trap
Answer: A
Rationale: The distribution box evenly directs effluent to drainfield
laterals.
© 2026 Academics_Excellence. All Rights Reserved.
,3. What is the purpose of a septic tank?
A. Disinfect wastewater
B. Separate solids and allow anaerobic digestion
C. Increase oxygen levels
D. Filter stormwater runoff
Answer: B
Rationale: Septic tanks settle solids and partially digest organic matter
anaerobically.
4. Which soil characteristic is most important for drainfield design?
A. Percolation rate
B. Soil color
C. Wind speed
D. Surface temperature
Answer: A
Rationale: Soil percolation determines how quickly effluent is absorbed.
5. What is the function of a drainfield?
A. Store sludge permanently
B. Disperse and treat effluent through soil absorption
© 2026 Academics_Excellence. All Rights Reserved.
,C. Increase wastewater flow
D. Pump sewage to surface waters
Answer: B
Rationale: Drainfields allow effluent to be treated naturally in soil.
6. Which test evaluates soil absorption capacity?
A. Percolation test
B. BOD test
C. pH test
D. Chlorine residual test
Answer: A
Rationale: Percolation tests measure how quickly water moves through
soil.
7. What is the purpose of gravel in a drainfield trench?
A. Increase wastewater toxicity
B. Provide void space for effluent distribution
C. Block effluent flow
D. Increase soil compaction
Answer: B
Rationale: Gravel supports pipe and allows effluent distribution into soil.
© 2026 Academics_Excellence. All Rights Reserved.
, 8. Which component prevents solids from entering the drainfield?
A. Septic tank
B. Pump chamber
C. Vent pipe
D. Alarm panel
Answer: A
Rationale: The septic tank retains solids before effluent reaches the
drainfield.
9. What is a common sign of a failing drainfield?
A. Sewage surfacing on the ground
B. Increased plant growth only
C. Clear effluent discharge
D. Reduced soil moisture
Answer: A
Rationale: Surface effluent indicates soil absorption failure.
10. Which condition shortens drainfield lifespan?
A. Soil saturation
B. Proper grading
© 2026 Academics_Excellence. All Rights Reserved.
Exam Prep | Questions And Answers With
Verified Rationales | 2026/27 Qs & Ans | Digital
Pdf Download
1. What is the primary purpose of an onsite wastewater system?
A. Increase groundwater pollution
B. Treat and safely dispose of wastewater on the property
C. Store untreated sewage indefinitely
D. Increase surface runoff
Answer: B
Rationale: Onsite systems treat and dispose of wastewater at or near the
point of generation.
2. Which system component distributes effluent into the soil?
A. Distribution box
B. Aeration blower
C. Chlorine tank
D. Grease trap
Answer: A
Rationale: The distribution box evenly directs effluent to drainfield
laterals.
© 2026 Academics_Excellence. All Rights Reserved.
,3. What is the purpose of a septic tank?
A. Disinfect wastewater
B. Separate solids and allow anaerobic digestion
C. Increase oxygen levels
D. Filter stormwater runoff
Answer: B
Rationale: Septic tanks settle solids and partially digest organic matter
anaerobically.
4. Which soil characteristic is most important for drainfield design?
A. Percolation rate
B. Soil color
C. Wind speed
D. Surface temperature
Answer: A
Rationale: Soil percolation determines how quickly effluent is absorbed.
5. What is the function of a drainfield?
A. Store sludge permanently
B. Disperse and treat effluent through soil absorption
© 2026 Academics_Excellence. All Rights Reserved.
,C. Increase wastewater flow
D. Pump sewage to surface waters
Answer: B
Rationale: Drainfields allow effluent to be treated naturally in soil.
6. Which test evaluates soil absorption capacity?
A. Percolation test
B. BOD test
C. pH test
D. Chlorine residual test
Answer: A
Rationale: Percolation tests measure how quickly water moves through
soil.
7. What is the purpose of gravel in a drainfield trench?
A. Increase wastewater toxicity
B. Provide void space for effluent distribution
C. Block effluent flow
D. Increase soil compaction
Answer: B
Rationale: Gravel supports pipe and allows effluent distribution into soil.
© 2026 Academics_Excellence. All Rights Reserved.
, 8. Which component prevents solids from entering the drainfield?
A. Septic tank
B. Pump chamber
C. Vent pipe
D. Alarm panel
Answer: A
Rationale: The septic tank retains solids before effluent reaches the
drainfield.
9. What is a common sign of a failing drainfield?
A. Sewage surfacing on the ground
B. Increased plant growth only
C. Clear effluent discharge
D. Reduced soil moisture
Answer: A
Rationale: Surface effluent indicates soil absorption failure.
10. Which condition shortens drainfield lifespan?
A. Soil saturation
B. Proper grading
© 2026 Academics_Excellence. All Rights Reserved.
