Onsite Wastewater System Installer Licensing
Exam Questions and Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of a septic tank?
A. Disinfect wastewater
B. Separate solids from liquids
C. Pump wastewater to drainfield
D. Neutralize chemicals
Answer: B
Rationale: A septic tank’s main function is to allow solids to settle and
scum to rise, separating them from liquid effluent.
2. Which soil type has the highest permeability?
A. Clay
B. Silt
,C. Sand
D. Loam
Answer: C
Rationale: Sand has large particles and pore spaces, allowing water to
move through it more quickly than other soil types.
3. What is the minimum separation distance between a septic tank
and a water well (typical code requirement)?
A. 10 feet
B. 25 feet
C. 50 feet
D. 100 feet
Answer: D
Rationale: Most codes require at least 100 feet separation to prevent
contamination of drinking water.
4. What does a perc test measure?
A. Water hardness
B. Soil absorption rate
,C. Bacteria levels
D. Pipe flow rate
Answer: B
Rationale: A percolation test evaluates how quickly soil absorbs water,
which determines drainfield suitability.
5. Which component distributes effluent evenly in a drainfield?
A. Pump tank
B. Distribution box
C. Grease trap
D. Effluent filter
Answer: B
Rationale: A distribution box splits wastewater evenly into multiple
drainfield lines.
6. What is the main function of a drainfield?
A. Store wastewater
B. Treat and disperse effluent into soil
C. Pump sewage
D. Filter solids
, Answer: B
Rationale: The drainfield allows treated effluent to infiltrate soil for final
treatment.
7. Which material is commonly used for septic tank construction?
A. Aluminum
B. Concrete
C. Copper
D. Wood
Answer: B
Rationale: Concrete is durable, resistant to corrosion, and widely used
for septic tanks.
8. What is scum in a septic tank?
A. Heavy solids at bottom
B. Floating oils and grease
C. Clear water layer
D. Soil particles
Exam Questions and Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a septic tank?
A. Disinfect wastewater
B. Separate solids from liquids
C. Pump wastewater to drainfield
D. Neutralize chemicals
Answer: B
Rationale: A septic tank’s main function is to allow solids to settle and
scum to rise, separating them from liquid effluent.
2. Which soil type has the highest permeability?
A. Clay
B. Silt
,C. Sand
D. Loam
Answer: C
Rationale: Sand has large particles and pore spaces, allowing water to
move through it more quickly than other soil types.
3. What is the minimum separation distance between a septic tank
and a water well (typical code requirement)?
A. 10 feet
B. 25 feet
C. 50 feet
D. 100 feet
Answer: D
Rationale: Most codes require at least 100 feet separation to prevent
contamination of drinking water.
4. What does a perc test measure?
A. Water hardness
B. Soil absorption rate
,C. Bacteria levels
D. Pipe flow rate
Answer: B
Rationale: A percolation test evaluates how quickly soil absorbs water,
which determines drainfield suitability.
5. Which component distributes effluent evenly in a drainfield?
A. Pump tank
B. Distribution box
C. Grease trap
D. Effluent filter
Answer: B
Rationale: A distribution box splits wastewater evenly into multiple
drainfield lines.
6. What is the main function of a drainfield?
A. Store wastewater
B. Treat and disperse effluent into soil
C. Pump sewage
D. Filter solids
, Answer: B
Rationale: The drainfield allows treated effluent to infiltrate soil for final
treatment.
7. Which material is commonly used for septic tank construction?
A. Aluminum
B. Concrete
C. Copper
D. Wood
Answer: B
Rationale: Concrete is durable, resistant to corrosion, and widely used
for septic tanks.
8. What is scum in a septic tank?
A. Heavy solids at bottom
B. Floating oils and grease
C. Clear water layer
D. Soil particles
