ONSITE WASTEWATER SYSTEMS EXAM 2026
QUESTIONS AND ANSWERS 100% CORRECT
Section 1: General Concepts
1. What is the primary purpose of an onsite wastewater treatment system?
A. To store wastewater indefinitely
B. To transport wastewater to municipal treatment plants
C. To treat and dispose of wastewater safely on-site
D. To evaporate wastewater
✅ Correct Answer: C
Explanation: Onsite systems treat wastewater using natural biological and soil processes before
safely dispersing it into the environment.
2. Which component is responsible for separating solids from liquids?
A. Drainfield
B. Distribution box
C. Septic tank
D. Soil absorption area
✅ Correct Answer: C
3. What type of wastewater does a typical residential system treat?
A. Stormwater only
B. Industrial waste
C. Blackwater and graywater
D. Agricultural runoff
✅ Correct Answer: C
4. Which material is commonly used for septic tanks?
A. Aluminum
B. Plastic, fiberglass, or concrete
C. Wood
D. Clay
✅ Correct Answer: B
, 5. Which layer forms at the top of a septic tank?
A. Effluent
B. Sludge
C. Scum
D. Biomass
✅ Correct Answer: C
Section 2: Septic Tank Operation
6. Sludge in a septic tank is composed primarily of:
A. Floating grease
B. Settled organic and inorganic solids
C. Clear water
D. Disinfectants
✅ Correct Answer: B
7. How often should a septic tank typically be pumped?
A. Every year
B. Every 2–5 years
C. Every 10 years
D. Only when it fails
✅ Correct Answer: B
8. What happens if a septic tank is not pumped regularly?
A. Improved treatment
B. Reduced odors
C. Solids enter the drainfield
D. Increased soil permeability
✅ Correct Answer: C
9. The inlet and outlet baffles in a septic tank are used to:
A. Speed up flow
B. Prevent solids from escaping
C. Increase pressure
D. Add oxygen
✅ Correct Answer: B
10. Which bacteria type is primarily responsible for digestion in septic tanks?
A. Aerobic
B. Anaerobic
QUESTIONS AND ANSWERS 100% CORRECT
Section 1: General Concepts
1. What is the primary purpose of an onsite wastewater treatment system?
A. To store wastewater indefinitely
B. To transport wastewater to municipal treatment plants
C. To treat and dispose of wastewater safely on-site
D. To evaporate wastewater
✅ Correct Answer: C
Explanation: Onsite systems treat wastewater using natural biological and soil processes before
safely dispersing it into the environment.
2. Which component is responsible for separating solids from liquids?
A. Drainfield
B. Distribution box
C. Septic tank
D. Soil absorption area
✅ Correct Answer: C
3. What type of wastewater does a typical residential system treat?
A. Stormwater only
B. Industrial waste
C. Blackwater and graywater
D. Agricultural runoff
✅ Correct Answer: C
4. Which material is commonly used for septic tanks?
A. Aluminum
B. Plastic, fiberglass, or concrete
C. Wood
D. Clay
✅ Correct Answer: B
, 5. Which layer forms at the top of a septic tank?
A. Effluent
B. Sludge
C. Scum
D. Biomass
✅ Correct Answer: C
Section 2: Septic Tank Operation
6. Sludge in a septic tank is composed primarily of:
A. Floating grease
B. Settled organic and inorganic solids
C. Clear water
D. Disinfectants
✅ Correct Answer: B
7. How often should a septic tank typically be pumped?
A. Every year
B. Every 2–5 years
C. Every 10 years
D. Only when it fails
✅ Correct Answer: B
8. What happens if a septic tank is not pumped regularly?
A. Improved treatment
B. Reduced odors
C. Solids enter the drainfield
D. Increased soil permeability
✅ Correct Answer: C
9. The inlet and outlet baffles in a septic tank are used to:
A. Speed up flow
B. Prevent solids from escaping
C. Increase pressure
D. Add oxygen
✅ Correct Answer: B
10. Which bacteria type is primarily responsible for digestion in septic tanks?
A. Aerobic
B. Anaerobic
