1|Page
TEXAS OSSF INSTALLER I LICENSE ACTUAL
EXAM PREP 2026 ALL QUESTIONS AND
CORRECT DETAILED ANSWERS WITH
RATIONALES ALREADY A GRADED WITH
EXPERT FEEDBACK |NEW AND REVISED
1. Under 30 Texas Administrative Code (TAC) Chapter 285, an OSSF
Installer I license authorizes the installation of which type of system?
A. Aerobic treatment units (ATUs) and advanced treatment systems
B. Septic tanks, absorptive drainfields, and pumped effluent
drainfields
C. All types of on-site sewage facilities regardless of complexity
D. Holding tanks and chemical toilets only
Rationale: An Installer I license authorizes the construction of
standard OSSF systems including septic tanks, absorptive drainfields,
unlined ET drainfields, leaching chambers, gravel-less pipe, and
pumped effluent drainfields. Installer II is required for advanced
treatment units such as aerobic treatment units (30 TAC §285.50(h)).
2. A licensed OSSF Installer I is preparing to install a conventional
septic system. Which regulatory chapter establishes the principal
minimum standards for the planning, permitting, construction, and
installation of OSSFs in Texas?
A. Texas Water Code Chapter 49
B. 30 Texas Administrative Code Chapter 285
C. Texas Health and Safety Code Chapter 366
D. 30 Texas Administrative Code Chapter 30
,2|Page
Rationale: 30 TAC Chapter 285 establishes the principal minimum
standards for OSSF planning, permitting, construction, and
installation. Chapter 30 covers occupational licenses and registrations.
The Texas Water Code and Health and Safety Code provide statutory
authority but do not contain the detailed installation standards.
3. An installer is preparing planning materials for a proposed OSSF that
does not require preparation of plans by a professional engineer or
registered sanitarian. Who is authorized to prepare these planning
materials?
A. Only a licensed site evaluator
B. Either the owner or the installer
C. Only a licensed professional engineer
D. Only a designated representative of the permitting authority
Rationale: Under 30 TAC §285.5, either the owner or installer may
prepare the planning materials for any proposed OSSF not requiring
preparation of plans according to paragraphs (2) or (3) of the
subsection. This allows installers to prepare plans for standard
systems.
4. What is the minimum liability insurance coverage required for an
OSSF Installer I license holder in Texas?
A. $100,000 per occurrence / $200,000 aggregate
B. **$300,000 aggregate**
C. $500,000 aggregate
D. $1,000,000 aggregate
Rationale: TCEQ requires OSSF Installer I license holders to carry
minimum liability insurance of $300,000 aggregate. This is a
requirement for obtaining and maintaining the license.
,3|Page
5. An OSSF Installer I must submit the installation report to the
permitting authority within what timeframe after completion of the
installation?
A. 3 days
B. 10 days
C. 30 days
D. 60 days
Rationale: TCEQ rules require the installer to submit the installation
report to the permitting authority within 30 days of completion. Form
20054 (On-Site Sewage Facility Installation Report) is used for this
purpose.
6. An installer is preparing to construct an OSSF. Before beginning
construction, the installer must notify the permitting authority at least
how many working days before the date the OSSF will be inspected?
A. 2 working days
B. 5 working days
C. 7 working days
D. 10 working days
Rationale: Under 30 TAC §285.61, the installer shall notify the
permitting authority at least five working days (Monday through
Friday, excluding holidays) before the date the OSSF will be ready for
inspection.
7. A homeowner wishes to install their own septic system on their
single-family residence. Under TCEQ rules, which of the following is
true?
A. The homeowner must hire a licensed Installer I regardless of
circumstances.
B. The homeowner may install or repair the OSSF on their own
single-family residence without a license.
, 4|Page
C. The homeowner may install the system but must have a licensed
installer supervise.
D. The homeowner may only install holding tanks, not septic systems.
Rationale: Under 30 TAC §30.244, persons who own a single-family
dwelling are not required to be licensed installers in order to install or
repair the OSSF serving that dwelling. However, all other TCEQ
requirements still apply.
8. A licensed Installer I is installing a septic tank. What is the minimum
required total liquid depth for the tank?
A. 24 inches
B. 30 inches
C. 36 inches
D. 48 inches
Rationale: TCEQ rules require septic tanks to have a minimum total
liquid depth of 30 inches. The outlet liquid penetration must be 25% to
50% of the total liquid depth.
9. For a gravity disposal system, what is the minimum required drop in
elevation from the bottom of the septic tank outlet pipe to the bottom of
the disposal area?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: For gravity disposal systems, septic tanks must be installed
with at least a 12-inch drop in elevation from the bottom of the outlet
pipe to the bottom of the disposal area to ensure proper flow.
10. An installer is constructing a sewer line from the building to the
septic tank. What is the minimum required slope for this line?
TEXAS OSSF INSTALLER I LICENSE ACTUAL
EXAM PREP 2026 ALL QUESTIONS AND
CORRECT DETAILED ANSWERS WITH
RATIONALES ALREADY A GRADED WITH
EXPERT FEEDBACK |NEW AND REVISED
1. Under 30 Texas Administrative Code (TAC) Chapter 285, an OSSF
Installer I license authorizes the installation of which type of system?
A. Aerobic treatment units (ATUs) and advanced treatment systems
B. Septic tanks, absorptive drainfields, and pumped effluent
drainfields
C. All types of on-site sewage facilities regardless of complexity
D. Holding tanks and chemical toilets only
Rationale: An Installer I license authorizes the construction of
standard OSSF systems including septic tanks, absorptive drainfields,
unlined ET drainfields, leaching chambers, gravel-less pipe, and
pumped effluent drainfields. Installer II is required for advanced
treatment units such as aerobic treatment units (30 TAC §285.50(h)).
2. A licensed OSSF Installer I is preparing to install a conventional
septic system. Which regulatory chapter establishes the principal
minimum standards for the planning, permitting, construction, and
installation of OSSFs in Texas?
A. Texas Water Code Chapter 49
B. 30 Texas Administrative Code Chapter 285
C. Texas Health and Safety Code Chapter 366
D. 30 Texas Administrative Code Chapter 30
,2|Page
Rationale: 30 TAC Chapter 285 establishes the principal minimum
standards for OSSF planning, permitting, construction, and
installation. Chapter 30 covers occupational licenses and registrations.
The Texas Water Code and Health and Safety Code provide statutory
authority but do not contain the detailed installation standards.
3. An installer is preparing planning materials for a proposed OSSF that
does not require preparation of plans by a professional engineer or
registered sanitarian. Who is authorized to prepare these planning
materials?
A. Only a licensed site evaluator
B. Either the owner or the installer
C. Only a licensed professional engineer
D. Only a designated representative of the permitting authority
Rationale: Under 30 TAC §285.5, either the owner or installer may
prepare the planning materials for any proposed OSSF not requiring
preparation of plans according to paragraphs (2) or (3) of the
subsection. This allows installers to prepare plans for standard
systems.
4. What is the minimum liability insurance coverage required for an
OSSF Installer I license holder in Texas?
A. $100,000 per occurrence / $200,000 aggregate
B. **$300,000 aggregate**
C. $500,000 aggregate
D. $1,000,000 aggregate
Rationale: TCEQ requires OSSF Installer I license holders to carry
minimum liability insurance of $300,000 aggregate. This is a
requirement for obtaining and maintaining the license.
,3|Page
5. An OSSF Installer I must submit the installation report to the
permitting authority within what timeframe after completion of the
installation?
A. 3 days
B. 10 days
C. 30 days
D. 60 days
Rationale: TCEQ rules require the installer to submit the installation
report to the permitting authority within 30 days of completion. Form
20054 (On-Site Sewage Facility Installation Report) is used for this
purpose.
6. An installer is preparing to construct an OSSF. Before beginning
construction, the installer must notify the permitting authority at least
how many working days before the date the OSSF will be inspected?
A. 2 working days
B. 5 working days
C. 7 working days
D. 10 working days
Rationale: Under 30 TAC §285.61, the installer shall notify the
permitting authority at least five working days (Monday through
Friday, excluding holidays) before the date the OSSF will be ready for
inspection.
7. A homeowner wishes to install their own septic system on their
single-family residence. Under TCEQ rules, which of the following is
true?
A. The homeowner must hire a licensed Installer I regardless of
circumstances.
B. The homeowner may install or repair the OSSF on their own
single-family residence without a license.
, 4|Page
C. The homeowner may install the system but must have a licensed
installer supervise.
D. The homeowner may only install holding tanks, not septic systems.
Rationale: Under 30 TAC §30.244, persons who own a single-family
dwelling are not required to be licensed installers in order to install or
repair the OSSF serving that dwelling. However, all other TCEQ
requirements still apply.
8. A licensed Installer I is installing a septic tank. What is the minimum
required total liquid depth for the tank?
A. 24 inches
B. 30 inches
C. 36 inches
D. 48 inches
Rationale: TCEQ rules require septic tanks to have a minimum total
liquid depth of 30 inches. The outlet liquid penetration must be 25% to
50% of the total liquid depth.
9. For a gravity disposal system, what is the minimum required drop in
elevation from the bottom of the septic tank outlet pipe to the bottom of
the disposal area?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: For gravity disposal systems, septic tanks must be installed
with at least a 12-inch drop in elevation from the bottom of the outlet
pipe to the bottom of the disposal area to ensure proper flow.
10. An installer is constructing a sewer line from the building to the
septic tank. What is the minimum required slope for this line?
