OSSF Installer 1 License Exam – 100-Question Practice Test
Latest 2026 Edition | Questions, Answers, and Explanations|
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1. What does “OSSF” stand for?
A. Onsite Sanitation System Function
B. On-Site Sewage Facility
C. Operational Soil Safety Factor
D. Organic System Safety Formula
OSSF refers to systems that treat and dispose of household wastewater on the
property where it is generated.
2. The primary goal of an OSSF system is to:
A. Collect stormwater
B. Provide potable water
C. Treat and disperse wastewater
D. Store waste
OSSF systems treat sewage and safely return effluent to the environment.
3. The typical minimum separation from a drainfield to a potable water well is:
A. 10 feet
B. 50 feet
C. 100 feet
D. 500 feet
Separation prevents contamination of drinking water supplies.
,4. A percolation (perc) test measures:
A. Soil acidity
B. Soil absorption rate
C. Water hardness
D. Soil organic content
Perc tests determine how quickly water moves through soil — critical for OSSF
design.
5. Which soil type generally has the fastest infiltration rate?
A. Clay
B. Sandy soil
C. Loam
D. Peat
Sandy soils allow water to move quickly, whereas clay is slow.
6. What component separates solids from effluent in a septic system?
A. Distribution box
B. Treatment plant
C. Septic tank
D. Absorption trench
The septic tank settles solids and begins anaerobic treatment.
7. How often should a typical septic tank be pumped?
,A. Every month
B. Every 1–3 years
C. Every 10 years
D. Never
Regular pumping prevents solids from entering the drainfield.
8. The drainfield is also called the:
A. Effluent chamber
B. Absorption field
C. Sewer line
D. Primary tank
The drainfield disperses treated effluent into the soil.
9. Which factor most influences drainfield size?
A. Household income
B. Soil percolation rate
C. Roof area
D. Driveway length
Slow soils require larger absorption areas.
10. What angle should trenched sides typically be cut?
A. 45°
B. 60°
C. 90°
D. Flat
, 45° sidewalls help maintain trench stability.
11. The purpose of a distribution box (D-box) is to:
A. Pump effluent
B. Distribute effluent evenly to trenches
C. Filter solids
D. Aerate wastewater
Even distribution ensures proper system function.
12. A common sign of a failing OSSF drainfield is:
A. Tall grass
B. Puddling or soggy soil above trenches
C. Dry soil
D. Increased vegetation color
Standing water indicates poor soil absorption or clogging.
13. What is a setback?
A. A construction delay
B. Minimum distance between system and features like wells or property
lines
C. A type of septic tank
D. A treatment process
Setbacks protect public health and water quality.
Latest 2026 Edition | Questions, Answers, and Explanations|
Instant Pdf Access After Payment
1. What does “OSSF” stand for?
A. Onsite Sanitation System Function
B. On-Site Sewage Facility
C. Operational Soil Safety Factor
D. Organic System Safety Formula
OSSF refers to systems that treat and dispose of household wastewater on the
property where it is generated.
2. The primary goal of an OSSF system is to:
A. Collect stormwater
B. Provide potable water
C. Treat and disperse wastewater
D. Store waste
OSSF systems treat sewage and safely return effluent to the environment.
3. The typical minimum separation from a drainfield to a potable water well is:
A. 10 feet
B. 50 feet
C. 100 feet
D. 500 feet
Separation prevents contamination of drinking water supplies.
,4. A percolation (perc) test measures:
A. Soil acidity
B. Soil absorption rate
C. Water hardness
D. Soil organic content
Perc tests determine how quickly water moves through soil — critical for OSSF
design.
5. Which soil type generally has the fastest infiltration rate?
A. Clay
B. Sandy soil
C. Loam
D. Peat
Sandy soils allow water to move quickly, whereas clay is slow.
6. What component separates solids from effluent in a septic system?
A. Distribution box
B. Treatment plant
C. Septic tank
D. Absorption trench
The septic tank settles solids and begins anaerobic treatment.
7. How often should a typical septic tank be pumped?
,A. Every month
B. Every 1–3 years
C. Every 10 years
D. Never
Regular pumping prevents solids from entering the drainfield.
8. The drainfield is also called the:
A. Effluent chamber
B. Absorption field
C. Sewer line
D. Primary tank
The drainfield disperses treated effluent into the soil.
9. Which factor most influences drainfield size?
A. Household income
B. Soil percolation rate
C. Roof area
D. Driveway length
Slow soils require larger absorption areas.
10. What angle should trenched sides typically be cut?
A. 45°
B. 60°
C. 90°
D. Flat
, 45° sidewalls help maintain trench stability.
11. The purpose of a distribution box (D-box) is to:
A. Pump effluent
B. Distribute effluent evenly to trenches
C. Filter solids
D. Aerate wastewater
Even distribution ensures proper system function.
12. A common sign of a failing OSSF drainfield is:
A. Tall grass
B. Puddling or soggy soil above trenches
C. Dry soil
D. Increased vegetation color
Standing water indicates poor soil absorption or clogging.
13. What is a setback?
A. A construction delay
B. Minimum distance between system and features like wells or property
lines
C. A type of septic tank
D. A treatment process
Setbacks protect public health and water quality.
