Minnesota Subsurface Sewage
Treatment System Designer Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a Subsurface Sewage Treatment
System (SSTS) designer?
A. To operate wastewater treatment plants
B. To design systems that safely treat and disperse wastewater
C. To inspect only plumbing fixtures
D. To manufacture septic tanks
Answer: B. To design systems that safely treat and disperse wastewater
The SSTS designer’s role is to develop treatment and dispersal designs that
protect public health and the environment by ensuring wastewater is
properly treated before entering the soil.
, 2. Which Minnesota agency establishes statewide rules governing
Subsurface Sewage Treatment Systems?
A. Minnesota Department of Transportation
B. Minnesota Pollution Control Agency
C. Minnesota Department of Agriculture
D. Minnesota Department of Commerce
Answer: B. Minnesota Pollution Control Agency
The Minnesota Pollution Control Agency regulates SSTS standards,
licensing, and technical requirements to protect groundwater and public
health.
3. The main function of a septic tank in an SSTS is to:
A. Fully disinfect wastewater
B. Remove solids and allow partial treatment
C. Increase wastewater temperature
D. Pump wastewater directly into groundwater
Answer: B. Remove solids and allow partial treatment
A septic tank provides settling of solids and anaerobic digestion while
allowing clarified effluent to flow to the soil treatment area.
4. Soil treatment areas are designed primarily to:
,A. Store wastewater indefinitely
B. Remove contaminants through soil treatment processes
C. Replace septic tanks
D. Increase water pressure
Answer: B. Remove contaminants through soil treatment processes
The soil treatment area uses physical, chemical, and biological processes to
treat effluent before it reaches groundwater.
5. Which soil characteristic is most important when designing an SSTS?
A. Soil color only
B. Soil texture and structure
C. Surface vegetation only
D. Rock size above ground
Answer: B. Soil texture and structure
Soil texture and structure determine wastewater movement, treatment
capacity, and the required sizing of the system.
6. The limiting soil layer is important because it:
A. Determines septic tank color
B. Controls separation distance and treatment capacity
, C. Eliminates the need for inspection
D. Increases household water use
Answer: B. Controls separation distance and treatment capacity
The limiting layer, such as a water table or restrictive soil, determines how
much treatment soil is available beneath the dispersal system.
7. Which soil has the slowest wastewater movement?
A. Sand
B. Gravel
C. Clay
D. Coarse sand
Answer: C. Clay
Clay has very small particles and low permeability, causing slow movement
of wastewater and potential ponding.
8. The design flow for a residential SSTS is generally based on:
A. Property value
B. Number of bedrooms and expected occupancy
C. Soil color
D. Distance from roads
Answer: B. Number of bedrooms and expected occupancy
Treatment System Designer Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a Subsurface Sewage Treatment
System (SSTS) designer?
A. To operate wastewater treatment plants
B. To design systems that safely treat and disperse wastewater
C. To inspect only plumbing fixtures
D. To manufacture septic tanks
Answer: B. To design systems that safely treat and disperse wastewater
The SSTS designer’s role is to develop treatment and dispersal designs that
protect public health and the environment by ensuring wastewater is
properly treated before entering the soil.
, 2. Which Minnesota agency establishes statewide rules governing
Subsurface Sewage Treatment Systems?
A. Minnesota Department of Transportation
B. Minnesota Pollution Control Agency
C. Minnesota Department of Agriculture
D. Minnesota Department of Commerce
Answer: B. Minnesota Pollution Control Agency
The Minnesota Pollution Control Agency regulates SSTS standards,
licensing, and technical requirements to protect groundwater and public
health.
3. The main function of a septic tank in an SSTS is to:
A. Fully disinfect wastewater
B. Remove solids and allow partial treatment
C. Increase wastewater temperature
D. Pump wastewater directly into groundwater
Answer: B. Remove solids and allow partial treatment
A septic tank provides settling of solids and anaerobic digestion while
allowing clarified effluent to flow to the soil treatment area.
4. Soil treatment areas are designed primarily to:
,A. Store wastewater indefinitely
B. Remove contaminants through soil treatment processes
C. Replace septic tanks
D. Increase water pressure
Answer: B. Remove contaminants through soil treatment processes
The soil treatment area uses physical, chemical, and biological processes to
treat effluent before it reaches groundwater.
5. Which soil characteristic is most important when designing an SSTS?
A. Soil color only
B. Soil texture and structure
C. Surface vegetation only
D. Rock size above ground
Answer: B. Soil texture and structure
Soil texture and structure determine wastewater movement, treatment
capacity, and the required sizing of the system.
6. The limiting soil layer is important because it:
A. Determines septic tank color
B. Controls separation distance and treatment capacity
, C. Eliminates the need for inspection
D. Increases household water use
Answer: B. Controls separation distance and treatment capacity
The limiting layer, such as a water table or restrictive soil, determines how
much treatment soil is available beneath the dispersal system.
7. Which soil has the slowest wastewater movement?
A. Sand
B. Gravel
C. Clay
D. Coarse sand
Answer: C. Clay
Clay has very small particles and low permeability, causing slow movement
of wastewater and potential ponding.
8. The design flow for a residential SSTS is generally based on:
A. Property value
B. Number of bedrooms and expected occupancy
C. Soil color
D. Distance from roads
Answer: B. Number of bedrooms and expected occupancy
