Alaska Onsite Wastewater Installer
Certification Exam Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A
1. What is the primary purpose of an onsite wastewater treatment system?
A. To disinfect drinking water
B. To safely treat and dispose of household wastewater
C. To store rainwater
D. To recycle graywater only
Answer: B
Onsite wastewater systems are designed to treat and disperse wastewater in a
way that protects public health and the environment.
2. Which component of a septic system is responsible for separating solids
from liquids?
A. Distribution box
B. Drainfield
C. Septic tank
D. Soil absorption trench
Answer: C
The septic tank allows solids to settle as sludge and float as scum, separating
them from effluent.
3. What type of soil has the slowest percolation rate?
A. Sandy soil
B. Loamy soil
C. Silty soil
D. Clay soil
,Answer: D
Clay soils have very small pore spaces, which significantly slow water movement.
4. In Alaska, which condition most strongly affects onsite wastewater system
design?
A. High population density
B. Permafrost
C. High rainfall year-round
D. Industrial wastewater discharge
Answer: B
Permafrost restricts soil absorption and requires special system designs.
5. What is the minimum function of the drainfield?
A. To store wastewater
B. To disinfect wastewater
C. To disperse treated effluent into the soil
D. To remove grease
Answer: C
The drainfield allows treated effluent to infiltrate soil for final treatment.
6. Which wastewater component contributes most to biological oxygen
demand (BOD)?
A. Pathogens
B. Nutrients
C. Organic matter
D. Inorganic salts
Answer: C
Organic matter requires oxygen for decomposition, increasing BOD.
, 7. What is the primary risk of installing a septic system too close to
groundwater?
A. Pipe freezing
B. Odor problems
C. Groundwater contamination
D. Increased maintenance costs
Answer: C
Insufficient separation allows pathogens and nutrients to contaminate
groundwater.
8. Which permit is typically required before installing an onsite wastewater
system in Alaska?
A. Building permit
B. Electrical permit
C. DEC approval
D. Zoning variance
Answer: C
The Alaska Department of Environmental Conservation (DEC) regulates onsite
wastewater systems.
9. What is the purpose of a distribution box?
A. To collect sludge
B. To evenly distribute effluent to the drainfield
C. To disinfect wastewater
D. To vent sewer gases
Answer: B
The distribution box ensures equal flow to multiple absorption lines.
10.Which material is most commonly used for septic tanks?
A. Steel
B. Wood
Certification Exam Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A
1. What is the primary purpose of an onsite wastewater treatment system?
A. To disinfect drinking water
B. To safely treat and dispose of household wastewater
C. To store rainwater
D. To recycle graywater only
Answer: B
Onsite wastewater systems are designed to treat and disperse wastewater in a
way that protects public health and the environment.
2. Which component of a septic system is responsible for separating solids
from liquids?
A. Distribution box
B. Drainfield
C. Septic tank
D. Soil absorption trench
Answer: C
The septic tank allows solids to settle as sludge and float as scum, separating
them from effluent.
3. What type of soil has the slowest percolation rate?
A. Sandy soil
B. Loamy soil
C. Silty soil
D. Clay soil
,Answer: D
Clay soils have very small pore spaces, which significantly slow water movement.
4. In Alaska, which condition most strongly affects onsite wastewater system
design?
A. High population density
B. Permafrost
C. High rainfall year-round
D. Industrial wastewater discharge
Answer: B
Permafrost restricts soil absorption and requires special system designs.
5. What is the minimum function of the drainfield?
A. To store wastewater
B. To disinfect wastewater
C. To disperse treated effluent into the soil
D. To remove grease
Answer: C
The drainfield allows treated effluent to infiltrate soil for final treatment.
6. Which wastewater component contributes most to biological oxygen
demand (BOD)?
A. Pathogens
B. Nutrients
C. Organic matter
D. Inorganic salts
Answer: C
Organic matter requires oxygen for decomposition, increasing BOD.
, 7. What is the primary risk of installing a septic system too close to
groundwater?
A. Pipe freezing
B. Odor problems
C. Groundwater contamination
D. Increased maintenance costs
Answer: C
Insufficient separation allows pathogens and nutrients to contaminate
groundwater.
8. Which permit is typically required before installing an onsite wastewater
system in Alaska?
A. Building permit
B. Electrical permit
C. DEC approval
D. Zoning variance
Answer: C
The Alaska Department of Environmental Conservation (DEC) regulates onsite
wastewater systems.
9. What is the purpose of a distribution box?
A. To collect sludge
B. To evenly distribute effluent to the drainfield
C. To disinfect wastewater
D. To vent sewer gases
Answer: B
The distribution box ensures equal flow to multiple absorption lines.
10.Which material is most commonly used for septic tanks?
A. Steel
B. Wood
