TCEQ OSSF LICENSE ACTUAL EXAM AND STUDY GUIDE | COMPLETE 2025–2026
PREP |150 VERIFIED QUESTIONS AND ANSWERS WITH DETAILED RATIONALES
ALL NEEDED TO PASS TCEQ OSSF LICENSE EXAM
1. What does OSSF stand for?
A) On-Site Sewage Facility ✓
B) Off-Site Sanitation Facility
C) On-Stream Sanitation Function
D) Off-Site Sewage Function
Rationale: OSSF is the term used in Texas for systems treating sewage on the property where waste is
generated.
2. Which Texas agency regulates OSSFs?
A) EPA
B) TCEQ ✓
C) FDA
D) OSHA
Rationale: The Texas Commission on Environmental Quality (TCEQ) enforces rules for OSSFs.
3. The minimum vertical separation between the bottom of the absorption trench and the seasonally
high water table is:
A) 6 inches
B) 12 inches ✓
C) 18 inches
D) 24 inches
Rationale: TCEQ rules require at least 12 inches to prevent contamination and system failure.
4. Which soil type is considered most suitable for absorption fields?
A) Clay
B) Sandy loam ✓
C) Silt
D) Peat
Rationale: Sandy loam provides adequate drainage while retaining some moisture for treatment.
,5. What is the main purpose of a septic tank in an OSSF?
A) To aerate wastewater
B) To filter solids from wastewater ✓
C) To disinfect wastewater
D) To store water
Rationale: Septic tanks separate solids (sludge) from liquids (effluent) before discharge to the drain
field.
6. How often should a residential septic tank generally be pumped?
A) Every 6 months
B) Every 1–3 years ✓
C) Every 5 years
D) Only when overflowing
Rationale: Regular pumping prevents solids from entering the absorption field.
7. Which component in the OSSF removes pathogens through microbial action in soil?
A) Septic tank
B) Absorption field ✓
C) Distribution box
D) Pretreatment unit
Rationale: The soil treats effluent biologically, removing bacteria, viruses, and nutrients.
8. Which factor primarily determines the size of an absorption field?
A) House color
B) Soil type and percolation rate ✓
C) Age of home
D) Local water table depth only
Rationale: Soil permeability affects how quickly effluent infiltrates; slower soils require larger fields.
9. What is the purpose of a distribution box?
A) Store effluent
B) Evenly distribute effluent to trenches ✓
C) Aerate wastewater
D) Treat sludge
Rationale: A distribution box ensures uniform loading on all absorption trenches.
,10. According to TCEQ, which is considered a failing system?
A) A tank needing pumping
B) Sewage surfacing on the ground ✓
C) Low water usage
D) New installation
Rationale: Exposure of untreated effluent is a violation and a public health hazard.
11. Which method is used to determine soil percolation rate?
A) Soil texture test
B) Percolation (perc) test ✓
C) Water table test
D) Soil color assessment
Rationale: Perc tests measure how fast water drains through soil, informing system design.
12. Which component prevents solids from clogging the absorption field?
A) Pump chamber
B) Septic tank ✓
C) Absorption trench
D) Soil
Rationale: The septic tank retains solids, preventing premature clogging.
13. Minimum lot size for a standard OSSF is typically:
A) 5,000 sq ft
B) 1 acre ✓
C) 2 acres
D) 10 acres
Rationale: One acre is usually the minimum required for proper system function without risking
contamination.
14. What is the primary function of a soil evaluation for OSSF?
A) Determine tank material
B) Assess soil suitability for effluent absorption ✓
C) Measure water usage
D) Set property taxes
Rationale: Soil evaluation ensures the site can safely absorb and treat wastewater.
, 15. Which type of system is used when soil absorption is not feasible?
A) Standard septic
B) Aerobic treatment unit ✓
C) Conventional trench
D) Gravity system
Rationale: Aerobic treatment units are required when soils are unsuitable for conventional absorption
fields.
16. Which of the following is a typical sign of a clogged absorption trench?
A) Slow draining sinks
B) Sewage surfacing near trench ✓
C) Tank lid missing
D) Tree roots nearby
Rationale: Surface pooling indicates the soil cannot absorb effluent, signaling a clog.
17. How deep are typical absorption trenches?
A) 6–12 inches
B) 18–36 inches ✓
C) 4–6 feet
D) 5–10 feet
Rationale: Trench depth ensures proper soil treatment and avoids groundwater contamination.
18. Which document must be submitted to TCEQ before installing an OSSF?
A) Property deed
B) Permit application ✓
C) Septic tank bill
D) Soil test certificate only
Rationale: Permits ensure regulatory compliance and protect public health.
19. Which factor does NOT affect absorption field performance?
A) Soil permeability
B) Effluent flow rate
C) Daily water usage
D) Roof color ✓
Rationale: Roof color has no impact on system function.
PREP |150 VERIFIED QUESTIONS AND ANSWERS WITH DETAILED RATIONALES
ALL NEEDED TO PASS TCEQ OSSF LICENSE EXAM
1. What does OSSF stand for?
A) On-Site Sewage Facility ✓
B) Off-Site Sanitation Facility
C) On-Stream Sanitation Function
D) Off-Site Sewage Function
Rationale: OSSF is the term used in Texas for systems treating sewage on the property where waste is
generated.
2. Which Texas agency regulates OSSFs?
A) EPA
B) TCEQ ✓
C) FDA
D) OSHA
Rationale: The Texas Commission on Environmental Quality (TCEQ) enforces rules for OSSFs.
3. The minimum vertical separation between the bottom of the absorption trench and the seasonally
high water table is:
A) 6 inches
B) 12 inches ✓
C) 18 inches
D) 24 inches
Rationale: TCEQ rules require at least 12 inches to prevent contamination and system failure.
4. Which soil type is considered most suitable for absorption fields?
A) Clay
B) Sandy loam ✓
C) Silt
D) Peat
Rationale: Sandy loam provides adequate drainage while retaining some moisture for treatment.
,5. What is the main purpose of a septic tank in an OSSF?
A) To aerate wastewater
B) To filter solids from wastewater ✓
C) To disinfect wastewater
D) To store water
Rationale: Septic tanks separate solids (sludge) from liquids (effluent) before discharge to the drain
field.
6. How often should a residential septic tank generally be pumped?
A) Every 6 months
B) Every 1–3 years ✓
C) Every 5 years
D) Only when overflowing
Rationale: Regular pumping prevents solids from entering the absorption field.
7. Which component in the OSSF removes pathogens through microbial action in soil?
A) Septic tank
B) Absorption field ✓
C) Distribution box
D) Pretreatment unit
Rationale: The soil treats effluent biologically, removing bacteria, viruses, and nutrients.
8. Which factor primarily determines the size of an absorption field?
A) House color
B) Soil type and percolation rate ✓
C) Age of home
D) Local water table depth only
Rationale: Soil permeability affects how quickly effluent infiltrates; slower soils require larger fields.
9. What is the purpose of a distribution box?
A) Store effluent
B) Evenly distribute effluent to trenches ✓
C) Aerate wastewater
D) Treat sludge
Rationale: A distribution box ensures uniform loading on all absorption trenches.
,10. According to TCEQ, which is considered a failing system?
A) A tank needing pumping
B) Sewage surfacing on the ground ✓
C) Low water usage
D) New installation
Rationale: Exposure of untreated effluent is a violation and a public health hazard.
11. Which method is used to determine soil percolation rate?
A) Soil texture test
B) Percolation (perc) test ✓
C) Water table test
D) Soil color assessment
Rationale: Perc tests measure how fast water drains through soil, informing system design.
12. Which component prevents solids from clogging the absorption field?
A) Pump chamber
B) Septic tank ✓
C) Absorption trench
D) Soil
Rationale: The septic tank retains solids, preventing premature clogging.
13. Minimum lot size for a standard OSSF is typically:
A) 5,000 sq ft
B) 1 acre ✓
C) 2 acres
D) 10 acres
Rationale: One acre is usually the minimum required for proper system function without risking
contamination.
14. What is the primary function of a soil evaluation for OSSF?
A) Determine tank material
B) Assess soil suitability for effluent absorption ✓
C) Measure water usage
D) Set property taxes
Rationale: Soil evaluation ensures the site can safely absorb and treat wastewater.
, 15. Which type of system is used when soil absorption is not feasible?
A) Standard septic
B) Aerobic treatment unit ✓
C) Conventional trench
D) Gravity system
Rationale: Aerobic treatment units are required when soils are unsuitable for conventional absorption
fields.
16. Which of the following is a typical sign of a clogged absorption trench?
A) Slow draining sinks
B) Sewage surfacing near trench ✓
C) Tank lid missing
D) Tree roots nearby
Rationale: Surface pooling indicates the soil cannot absorb effluent, signaling a clog.
17. How deep are typical absorption trenches?
A) 6–12 inches
B) 18–36 inches ✓
C) 4–6 feet
D) 5–10 feet
Rationale: Trench depth ensures proper soil treatment and avoids groundwater contamination.
18. Which document must be submitted to TCEQ before installing an OSSF?
A) Property deed
B) Permit application ✓
C) Septic tank bill
D) Soil test certificate only
Rationale: Permits ensure regulatory compliance and protect public health.
19. Which factor does NOT affect absorption field performance?
A) Soil permeability
B) Effluent flow rate
C) Daily water usage
D) Roof color ✓
Rationale: Roof color has no impact on system function.
