1|Page
OSSF INSTALLER 1 TEST PREPARATION
LICENSE EXAM | ALL QUESTIONS AND
CORRECT DETAILED ANSWERS | RATED A + |
TOP RATED VERSION FOR 2026-2027 | NEW AND
REVISED
1. The primary purpose of an onsite sewage facility is to:
A. Dispose of stormwater runoff
B. Treat and disperse domestic wastewater safely
C. Collect industrial waste
D. Store wastewater indefinitely
Rationale: OSSF systems are designed to treat and
disperse household wastewater in a manner that protects
public health and groundwater.
2. Under Texas rules, an Installer I is authorized to install:
A. All aerobic and spray systems
B. Standard gravity septic systems
C. Commercial wastewater treatment plants
D. Municipal sewer lines
Rationale: Installer I licensure is limited primarily to
standard gravity systems.
3. Which agency regulates OSSF systems in Texas?
A. EPA
B. CDC
C. TCEQ
,2|Page
D. OSHA
Rationale: The Texas Commission on Environmental
Quality oversees OSSF rules and licensing.
4. A septic tank functions primarily to:
A. Kill all pathogens
B. Evaporate wastewater
C. Separate solids from liquids
D. Disinfect effluent
Rationale: Septic tanks allow solids to settle and scum to
rise, creating clarified effluent.
5. Which component prevents solids from entering the
drainfield?
A. Distribution box
B. Baffle or tee
C. Absorption trench
D. Soil
Rationale: Baffles or tees retain solids within the septic
tank.
6. Minimum liquid retention time in a septic tank is typically:
A. 6 hours
B. 12 hours
C. 24 hours
D. 72 hours
Rationale: A 24-hour retention time allows adequate
solids separation.
7. What is the main purpose of a drainfield?
A. Store wastewater
B. Filter rainwater
C. Disperse treated effluent into soil
D. Disinfect effluent
,3|Page
Rationale: Soil provides final treatment through
filtration and biological action.
8. Which soil texture generally provides the best effluent
treatment?
A. Gravel
B. Clay
C. Loam
D. Solid rock
Rationale: Loam balances permeability and filtration.
9. A site with shallow groundwater presents a risk primarily
of:
A. Pipe collapse
B. Groundwater contamination
C. Odor problems
D. Tank overflow
Rationale: Inadequate vertical separation can
contaminate groundwater.
10. The minimum separation between the drainfield and
groundwater is intended to:
A. Improve flow rate
B. Protect water quality
C. Reduce odors
D. Prevent freezing
Rationale: Vertical separation ensures adequate soil
treatment.
11. Which material is commonly used for septic tanks?
A. Wood
B. Concrete
C. Aluminum
D. PVC
Rationale: Concrete tanks are durable and watertight.
, 4|Page
12. The function of a distribution box is to:
A. Treat wastewater
B. Evenly distribute effluent to trenches
C. Store solids
D. Filter bacteria
Rationale: Proper distribution ensures equal loading.
13. A crushed or cracked septic tank is most likely caused
by:
A. Improper soil type
B. Vehicle traffic over the tank
C. Excessive rainfall
D. Poor effluent quality
Rationale: Tanks are not designed for live loads.
14. Which document authorizes installation of an OSSF
system?
A. Soil report
B. Construction permit
C. Maintenance contract
D. License certificate
Rationale: A permit is required before construction.
15. Installer I must follow which plans during installation?
A. Verbal instructions only
B. Approved permit and design
C. Manufacturer suggestions only
D. Property owner preference
Rationale: Installations must follow approved plans.
16. Effluent leaving a septic tank should be:
A. Clear and odorless
B. Free of large solids
C. Sterile
OSSF INSTALLER 1 TEST PREPARATION
LICENSE EXAM | ALL QUESTIONS AND
CORRECT DETAILED ANSWERS | RATED A + |
TOP RATED VERSION FOR 2026-2027 | NEW AND
REVISED
1. The primary purpose of an onsite sewage facility is to:
A. Dispose of stormwater runoff
B. Treat and disperse domestic wastewater safely
C. Collect industrial waste
D. Store wastewater indefinitely
Rationale: OSSF systems are designed to treat and
disperse household wastewater in a manner that protects
public health and groundwater.
2. Under Texas rules, an Installer I is authorized to install:
A. All aerobic and spray systems
B. Standard gravity septic systems
C. Commercial wastewater treatment plants
D. Municipal sewer lines
Rationale: Installer I licensure is limited primarily to
standard gravity systems.
3. Which agency regulates OSSF systems in Texas?
A. EPA
B. CDC
C. TCEQ
,2|Page
D. OSHA
Rationale: The Texas Commission on Environmental
Quality oversees OSSF rules and licensing.
4. A septic tank functions primarily to:
A. Kill all pathogens
B. Evaporate wastewater
C. Separate solids from liquids
D. Disinfect effluent
Rationale: Septic tanks allow solids to settle and scum to
rise, creating clarified effluent.
5. Which component prevents solids from entering the
drainfield?
A. Distribution box
B. Baffle or tee
C. Absorption trench
D. Soil
Rationale: Baffles or tees retain solids within the septic
tank.
6. Minimum liquid retention time in a septic tank is typically:
A. 6 hours
B. 12 hours
C. 24 hours
D. 72 hours
Rationale: A 24-hour retention time allows adequate
solids separation.
7. What is the main purpose of a drainfield?
A. Store wastewater
B. Filter rainwater
C. Disperse treated effluent into soil
D. Disinfect effluent
,3|Page
Rationale: Soil provides final treatment through
filtration and biological action.
8. Which soil texture generally provides the best effluent
treatment?
A. Gravel
B. Clay
C. Loam
D. Solid rock
Rationale: Loam balances permeability and filtration.
9. A site with shallow groundwater presents a risk primarily
of:
A. Pipe collapse
B. Groundwater contamination
C. Odor problems
D. Tank overflow
Rationale: Inadequate vertical separation can
contaminate groundwater.
10. The minimum separation between the drainfield and
groundwater is intended to:
A. Improve flow rate
B. Protect water quality
C. Reduce odors
D. Prevent freezing
Rationale: Vertical separation ensures adequate soil
treatment.
11. Which material is commonly used for septic tanks?
A. Wood
B. Concrete
C. Aluminum
D. PVC
Rationale: Concrete tanks are durable and watertight.
, 4|Page
12. The function of a distribution box is to:
A. Treat wastewater
B. Evenly distribute effluent to trenches
C. Store solids
D. Filter bacteria
Rationale: Proper distribution ensures equal loading.
13. A crushed or cracked septic tank is most likely caused
by:
A. Improper soil type
B. Vehicle traffic over the tank
C. Excessive rainfall
D. Poor effluent quality
Rationale: Tanks are not designed for live loads.
14. Which document authorizes installation of an OSSF
system?
A. Soil report
B. Construction permit
C. Maintenance contract
D. License certificate
Rationale: A permit is required before construction.
15. Installer I must follow which plans during installation?
A. Verbal instructions only
B. Approved permit and design
C. Manufacturer suggestions only
D. Property owner preference
Rationale: Installations must follow approved plans.
16. Effluent leaving a septic tank should be:
A. Clear and odorless
B. Free of large solids
C. Sterile
