TEXAS OSSF INSTALLER I
LICENSING EXAMINATION
PRACTICE TEST
30 TAC Chapter 285 | TCEQ Certification Prep
Licens
Multiple e Ren Regulati
Questions Choice 3-Ye ewal TCE ng Body
200 A–D ar Q
Exam Instructions
• Read each question carefully before selecting your answer.
• Each question has exactly one correct answer (A, B, C, or D).
• Correct answers and rationales are provided immediately after each question.
• Reference: 30 TAC Chapter 285 — On-Site Sewage Facilities.
• All setback distances reflect standard TCEQ Chapter 285 separation tables.
Questions 1 – 50
Texas OSSF Installer I Licensing Examination Practice Test | Page 1
,Question 1
What is the minimum required separation distance between a standard OSSF treatment tank and a
private water well?
A 10 feet
B 50 feet
C 100 feet
D 150 feet
Correct Answer: B | 30 TAC §285.91(10) mandates that a treatment tank (septic tank) must maintain a
minimum clear setback distance of 50 feet from any public or private water well.
Question 2
Under 30 TAC Chapter 285, an individual holding only an Installer I license is legally authorized to
install which of the following systems?
A Any system utilizing an aerobic treatment unit (ATU)
B Only conventional OSSF systems including absorptive trenches, beds, or unlined holes
C Drip emitter systems under the direct supervision of a Site Evaluator
D Any OSSF system as long as it serves a single-family dwelling flowing less than 500 GPD
Correct Answer: B | An Installer I license is restricted strictly to the installation of conventional OSSF
systems that rely on gravity flow, such as standard pipe and gravel trenches or beds. Advanced or
proprietary systems require an Installer II license.
Texas OSSF Installer I Licensing Examination Practice Test | Page 2
,Question 3
When installing a solid sewer pipe from the house stub-out to the pretreatment tank, what is the
minimum required downward slope?
A 1/16 inch per foot
B 1/8 inch per foot
C 1/4 inch per foot
D 1/2 inch per foot
Correct Answer: B | TCEQ rules state that the solid transport line from the structure to the treatment tank
must have a minimum downward pitch of 1/8 inch per foot (approximately a 1% grade) to ensure proper
movement of solid waste without clogging.
Question 4
While digging an absorption trench in a Class III clay-loam soil, the backhoe bucket glazes and
smears the sidewalls. What action must the installer take?
A No action is required if the gravel media weighs enough to break the glaze
B Coat the walls with a thin layer of sand before adding gravel
C Scarify or scratch the bottom and sidewalls to restore soil porosity
D Deepen the trench by exactly 12 inches to clear the smeared zone
Correct Answer: C | Smearing seals off the natural pores and spaces in the soil, which severely
decreases its ability to absorb liquid. Raking or scratching (scarifying) the smeared surfaces opens the soil
structure back up.
Texas OSSF Installer I Licensing Examination Practice Test | Page 3
, Question 5
What is the minimum required liquid capacity of a septic tank serving a 3-bedroom single-family
dwelling with an estimated flow of 300 GPD?
A 500 gallons
B 750 gallons
C 1,000 gallons
D 1,250 gallons
Correct Answer: C | According to 30 TAC §285.91(2), the minimum baseline septic tank capacity for a
single-family dwelling with a daily flow up to 350 GPD is 1,000 gallons.
Question 6
What is the maximum allowable length for a single conventional gravity distribution lateral line in
an absorption trench?
A 50 feet
B 75 feet
C 100 feet
D 150 feet
Correct Answer: C | A single distribution lateral line cannot exceed 100 feet in length. Lines longer than
100 feet lead to poor effluent distribution, overloading the front of the trench while leaving the end dry.
Texas OSSF Installer I Licensing Examination Practice Test | Page 4
LICENSING EXAMINATION
PRACTICE TEST
30 TAC Chapter 285 | TCEQ Certification Prep
Licens
Multiple e Ren Regulati
Questions Choice 3-Ye ewal TCE ng Body
200 A–D ar Q
Exam Instructions
• Read each question carefully before selecting your answer.
• Each question has exactly one correct answer (A, B, C, or D).
• Correct answers and rationales are provided immediately after each question.
• Reference: 30 TAC Chapter 285 — On-Site Sewage Facilities.
• All setback distances reflect standard TCEQ Chapter 285 separation tables.
Questions 1 – 50
Texas OSSF Installer I Licensing Examination Practice Test | Page 1
,Question 1
What is the minimum required separation distance between a standard OSSF treatment tank and a
private water well?
A 10 feet
B 50 feet
C 100 feet
D 150 feet
Correct Answer: B | 30 TAC §285.91(10) mandates that a treatment tank (septic tank) must maintain a
minimum clear setback distance of 50 feet from any public or private water well.
Question 2
Under 30 TAC Chapter 285, an individual holding only an Installer I license is legally authorized to
install which of the following systems?
A Any system utilizing an aerobic treatment unit (ATU)
B Only conventional OSSF systems including absorptive trenches, beds, or unlined holes
C Drip emitter systems under the direct supervision of a Site Evaluator
D Any OSSF system as long as it serves a single-family dwelling flowing less than 500 GPD
Correct Answer: B | An Installer I license is restricted strictly to the installation of conventional OSSF
systems that rely on gravity flow, such as standard pipe and gravel trenches or beds. Advanced or
proprietary systems require an Installer II license.
Texas OSSF Installer I Licensing Examination Practice Test | Page 2
,Question 3
When installing a solid sewer pipe from the house stub-out to the pretreatment tank, what is the
minimum required downward slope?
A 1/16 inch per foot
B 1/8 inch per foot
C 1/4 inch per foot
D 1/2 inch per foot
Correct Answer: B | TCEQ rules state that the solid transport line from the structure to the treatment tank
must have a minimum downward pitch of 1/8 inch per foot (approximately a 1% grade) to ensure proper
movement of solid waste without clogging.
Question 4
While digging an absorption trench in a Class III clay-loam soil, the backhoe bucket glazes and
smears the sidewalls. What action must the installer take?
A No action is required if the gravel media weighs enough to break the glaze
B Coat the walls with a thin layer of sand before adding gravel
C Scarify or scratch the bottom and sidewalls to restore soil porosity
D Deepen the trench by exactly 12 inches to clear the smeared zone
Correct Answer: C | Smearing seals off the natural pores and spaces in the soil, which severely
decreases its ability to absorb liquid. Raking or scratching (scarifying) the smeared surfaces opens the soil
structure back up.
Texas OSSF Installer I Licensing Examination Practice Test | Page 3
, Question 5
What is the minimum required liquid capacity of a septic tank serving a 3-bedroom single-family
dwelling with an estimated flow of 300 GPD?
A 500 gallons
B 750 gallons
C 1,000 gallons
D 1,250 gallons
Correct Answer: C | According to 30 TAC §285.91(2), the minimum baseline septic tank capacity for a
single-family dwelling with a daily flow up to 350 GPD is 1,000 gallons.
Question 6
What is the maximum allowable length for a single conventional gravity distribution lateral line in
an absorption trench?
A 50 feet
B 75 feet
C 100 feet
D 150 feet
Correct Answer: C | A single distribution lateral line cannot exceed 100 feet in length. Lines longer than
100 feet lead to poor effluent distribution, overloading the front of the trench while leaving the end dry.
Texas OSSF Installer I Licensing Examination Practice Test | Page 4
