TEXAS SEPTIC INSTALLER LICENSING EXAM — PRACTICE
QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF
1. The Texas Commission on Environmental Quality (TCEQ) regulates on-site
sewage facilities under which rule chapter?
A. Chapter 210
B. Chapter 285
C. Chapter 290
D. Chapter 336
Answer: B
Rationale: TCEQ Chapter 285 of the Texas Administrative Code governs On-Site
Sewage Facilities (OSSFs), including design, installation, and operation.
2. A standard subsurface disposal system typically includes:
A. Aerobic unit only
B. Septic tank and drainfield
C. Evapotranspiration bed
D. Surface application sprayers
Answer: B
Rationale: A conventional OSSF consists of a septic tank for treatment and a
subsurface drainfield for effluent disposal.
3. Minimum liquid capacity for a septic tank serving a 3-bedroom home is:
A. 500 gallons
B. 750 gallons
C. 1000 gallons
D. 1250 gallons
Answer: C
,Rationale: TCEQ requires a minimum 1,000-gallon tank for systems serving up to
3 bedrooms to ensure adequate retention and settling.
4. Soil texture affects:
A. Color of effluent
B. Absorption rate
C. Tank size
D. Pump capacity
Answer: B
Rationale: Soil texture determines infiltration and percolation rates, affecting
how quickly effluent disperses in the soil.
5. Which of the following soils is least suitable for a conventional drainfield?
A. Loamy sand
B. Sandy clay loam
C. Clay
D. Fine sand
Answer: C
Rationale: Clay soils have very low permeability, preventing proper effluent
absorption and causing ponding.
6. The minimum setback distance from a septic tank to a private water well is:
A. 25 feet
B. 50 feet
C. 100 feet
D. 150 feet
Answer: C
Rationale: Texas rules mandate at least 100 feet between a septic tank and a
private well to protect groundwater.
, 7. What is the primary purpose of a septic tank?
A. Store effluent indefinitely
B. Kill all bacteria
C. Separate solids and scum
D. Pump effluent to the field
Answer: C
Rationale: The septic tank allows solids to settle and scum to float, retaining
them while effluent exits for treatment.
8. Effluent filters are installed:
A. In the drainfield
B. At the outlet of the septic tank
C. At the building sewer
D. On the vent stack
Answer: B
Rationale: Effluent filters prevent solids from leaving the tank and clogging the
drainfield.
9. A percolation test measures:
A. Soil fertility
B. Groundwater level
C. Soil permeability
D. Tank leakage
Answer: C
Rationale: The percolation test determines how quickly water moves through
soil, which is critical for system sizing.
10. Septic tanks must be watertight to:
A. Prevent groundwater infiltration and leakage
B. Allow gases to escape
QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF
1. The Texas Commission on Environmental Quality (TCEQ) regulates on-site
sewage facilities under which rule chapter?
A. Chapter 210
B. Chapter 285
C. Chapter 290
D. Chapter 336
Answer: B
Rationale: TCEQ Chapter 285 of the Texas Administrative Code governs On-Site
Sewage Facilities (OSSFs), including design, installation, and operation.
2. A standard subsurface disposal system typically includes:
A. Aerobic unit only
B. Septic tank and drainfield
C. Evapotranspiration bed
D. Surface application sprayers
Answer: B
Rationale: A conventional OSSF consists of a septic tank for treatment and a
subsurface drainfield for effluent disposal.
3. Minimum liquid capacity for a septic tank serving a 3-bedroom home is:
A. 500 gallons
B. 750 gallons
C. 1000 gallons
D. 1250 gallons
Answer: C
,Rationale: TCEQ requires a minimum 1,000-gallon tank for systems serving up to
3 bedrooms to ensure adequate retention and settling.
4. Soil texture affects:
A. Color of effluent
B. Absorption rate
C. Tank size
D. Pump capacity
Answer: B
Rationale: Soil texture determines infiltration and percolation rates, affecting
how quickly effluent disperses in the soil.
5. Which of the following soils is least suitable for a conventional drainfield?
A. Loamy sand
B. Sandy clay loam
C. Clay
D. Fine sand
Answer: C
Rationale: Clay soils have very low permeability, preventing proper effluent
absorption and causing ponding.
6. The minimum setback distance from a septic tank to a private water well is:
A. 25 feet
B. 50 feet
C. 100 feet
D. 150 feet
Answer: C
Rationale: Texas rules mandate at least 100 feet between a septic tank and a
private well to protect groundwater.
, 7. What is the primary purpose of a septic tank?
A. Store effluent indefinitely
B. Kill all bacteria
C. Separate solids and scum
D. Pump effluent to the field
Answer: C
Rationale: The septic tank allows solids to settle and scum to float, retaining
them while effluent exits for treatment.
8. Effluent filters are installed:
A. In the drainfield
B. At the outlet of the septic tank
C. At the building sewer
D. On the vent stack
Answer: B
Rationale: Effluent filters prevent solids from leaving the tank and clogging the
drainfield.
9. A percolation test measures:
A. Soil fertility
B. Groundwater level
C. Soil permeability
D. Tank leakage
Answer: C
Rationale: The percolation test determines how quickly water moves through
soil, which is critical for system sizing.
10. Septic tanks must be watertight to:
A. Prevent groundwater infiltration and leakage
B. Allow gases to escape
