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TEXAS OSSF INSTALLER PRACTICE TEST 2026 TCEQ Exam Prep |
Questions with Answers & Rationales
Question 1
Which state agency regulates on-site sewage facilities (OSSFs) in
Texas?
A. Texas Department of Health
B. Texas Commission on Environmental Quality (TCEQ)
C. Texas Water Development Board
D. Texas Parks and Wildlife
Answer: B
Rationale: TCEQ regulates OSSFs under Texas Health and Safety
Code and 30 TAC Chapter 285.
Question 2
What is the minimum required separation distance from an
OSSF absorption area to a public water well?
A. 25 feet
B. 50 feet
C. 100 feet
D. 150 feet
Answer: B
Rationale: Generally, 50 feet minimum separation is required
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from absorption area to public water wells; private wells require
100 feet from septic tank and 150 feet from absorption field?
Actually private water wells require 100 ft from septic tank and
150 ft from drainfield? Need verify. Common: OSSF to private
water well: 100 ft from septic tank and 150 ft from absorption
area? Public water well 50 ft. But question asks public water
well, answer 50 feet. OK.
Question 3
Which of the following is the primary purpose of a septic tank?
A. To completely treat wastewater to drinking water quality
B. To separate solids from liquids and begin anaerobic digestion
C. To disinfect wastewater
D. To remove all nutrients
Answer: B
Rationale: Septic tanks allow solids to settle, scum to float, and
anaerobic bacteria to partially decompose organic matter.
Question 4
What is the minimum liquid capacity of a septic tank for a one-
or two-bedroom dwelling in Texas?
A. 500 gallons
B. 750 gallons
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C. 1000 gallons
D. 1200 gallons
Answer: C
Rationale: Minimum septic tank capacity for 1-2 bedrooms is
1000 gallons; 3 bedrooms is 1000 gallons? Actually 30 TAC 285:
minimum 1000 gal for up to 3 bedrooms? Need recall: 750 gal
for 1-2? Hmm. Let's recall Texas OSSF rules: Minimum septic
tank capacity:
• 1 or 2 bedrooms: 750 gallons?
• 3 bedrooms: 1000 gallons
• 4 bedrooms: 1250 gallons?
But many sources say minimum liquid capacity 750 gallons
for up to 3 bedrooms? Not sure. Common: septic tank min
750 gal for 1-2 bedroom, 1000 gal for 3 bedroom. The
question asks one- or two-bedroom; likely 750. Let's set B.
But we need accurate. Texas 30 TAC 285.91(b): minimum
septic tank capacity: 750 gallons for 1-2 bedrooms; 1000
for 3; 1250 for 4? Actually I think:
• 1-2 bedrooms: 750 gal
• 3 bedrooms: 1000 gal
• 4 bedrooms: 1250 gal
• each additional bedroom add 250 gal.
Yes. So answer B 750.
TEXAS OSSF INSTALLER PRACTICE TEST 2026 TCEQ Exam Prep |
Questions with Answers & Rationales
Question 1
Which state agency regulates on-site sewage facilities (OSSFs) in
Texas?
A. Texas Department of Health
B. Texas Commission on Environmental Quality (TCEQ)
C. Texas Water Development Board
D. Texas Parks and Wildlife
Answer: B
Rationale: TCEQ regulates OSSFs under Texas Health and Safety
Code and 30 TAC Chapter 285.
Question 2
What is the minimum required separation distance from an
OSSF absorption area to a public water well?
A. 25 feet
B. 50 feet
C. 100 feet
D. 150 feet
Answer: B
Rationale: Generally, 50 feet minimum separation is required
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from absorption area to public water wells; private wells require
100 feet from septic tank and 150 feet from absorption field?
Actually private water wells require 100 ft from septic tank and
150 ft from drainfield? Need verify. Common: OSSF to private
water well: 100 ft from septic tank and 150 ft from absorption
area? Public water well 50 ft. But question asks public water
well, answer 50 feet. OK.
Question 3
Which of the following is the primary purpose of a septic tank?
A. To completely treat wastewater to drinking water quality
B. To separate solids from liquids and begin anaerobic digestion
C. To disinfect wastewater
D. To remove all nutrients
Answer: B
Rationale: Septic tanks allow solids to settle, scum to float, and
anaerobic bacteria to partially decompose organic matter.
Question 4
What is the minimum liquid capacity of a septic tank for a one-
or two-bedroom dwelling in Texas?
A. 500 gallons
B. 750 gallons
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C. 1000 gallons
D. 1200 gallons
Answer: C
Rationale: Minimum septic tank capacity for 1-2 bedrooms is
1000 gallons; 3 bedrooms is 1000 gallons? Actually 30 TAC 285:
minimum 1000 gal for up to 3 bedrooms? Need recall: 750 gal
for 1-2? Hmm. Let's recall Texas OSSF rules: Minimum septic
tank capacity:
• 1 or 2 bedrooms: 750 gallons?
• 3 bedrooms: 1000 gallons
• 4 bedrooms: 1250 gallons?
But many sources say minimum liquid capacity 750 gallons
for up to 3 bedrooms? Not sure. Common: septic tank min
750 gal for 1-2 bedroom, 1000 gal for 3 bedroom. The
question asks one- or two-bedroom; likely 750. Let's set B.
But we need accurate. Texas 30 TAC 285.91(b): minimum
septic tank capacity: 750 gallons for 1-2 bedrooms; 1000
for 3; 1250 for 4? Actually I think:
• 1-2 bedrooms: 750 gal
• 3 bedrooms: 1000 gal
• 4 bedrooms: 1250 gal
• each additional bedroom add 250 gal.
Yes. So answer B 750.
