Page 1 of 227
Mississippi Individual Onsite Wastewater
Installer -Licensing Exam QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES JUST
RELEASED
Mississippi Individual Onsite Wastewater Installer Licensing Exam
EXAM COVERAGE (Point Form)
• Onsite Wastewater System Regulations & Installer Responsibilities (Core Exam
Area)
• Site Evaluation & Soil Assessment
• Septic Tanks & Pretreatment Components
• Soil Absorption Systems & Drainfields
• Onsite Wastewater System Components
• Installation Procedures & Construction Standards
• System Operation, Maintenance & Troubleshooting
• Safety, Environmental Protection & Public Health
• Inspection, Documentation & Code Compliance
QUESTIONS 1-300
1. A homeowner in Mississippi is planning to install a new onsite wastewater system on a
property with a seasonal high water table at 18 inches below the surface. According to
MSDH regulations, what is the minimum required depth between the bottom of the
drainfield trench and the seasonal high water table to ensure proper treatment and prevent
groundwater contamination?
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A. 6 inches, which is sufficient for most soil types and seasonal conditions.
B. 12 inches, because this provides adequate separation for treatment in all soils.
C. 24 inches, which is the minimum vertical separation required by MSDH regulations to protect
groundwater.
D. 36 inches, which ensures complete treatment even during periods of heavy rainfall.
Correct Answer: C
Rationale: Mississippi State Department of Health regulations require a minimum vertical
separation of 24 inches between the bottom of the drainfield trench and the seasonal high water
table . This separation is essential to ensure adequate soil treatment of effluent before it reaches
groundwater.
2. A certified installer is preparing to install a septic tank on a property with a high water
table. Which of the following is the MOST critical consideration to prevent the tank from
floating out of the ground during installation and operation?
A. The tank must be filled with water immediately after placement to provide counterweight
against buoyancy forces.
B. The tank must be placed on a compacted gravel base to provide stability.
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C. The tank must be anchored to a concrete base or have anti-flotation devices installed to
prevent buoyancy.
D. The tank must be backfilled with sand to allow drainage and prevent flotation.
Correct Answer: C
Rationale: Septic tanks must be anchored to a concrete base or have anti-flotation devices
installed in high water table areas . Empty tanks can float out of the ground when groundwater
rises, causing damage to the system.
3. During a site evaluation, an installer observes that the soil has a high clay content and
slow percolation rate. According to MSDH regulations, what is the MOST appropriate
action for designing the onsite wastewater system?
A. Install a conventional septic tank and drainfield without modification, as clay soils provide
good filtration.
B. Increase the size of the drainfield to compensate for the slow percolation rate and consider
alternative system design.
C. Install a cesspool instead of a septic tank because clay soils are suitable for cesspool
construction.
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D. Recommend that the homeowner abandon the site and purchase a different property for
development.
Correct Answer: B
Rationale: High clay content and slow percolation rates require larger drainfields or alternative
system designs to ensure adequate treatment . The installer must evaluate site conditions and
design a system that meets MSDH requirements.
4. A homeowner reports that their septic system is experiencing backups and slow drainage
throughout the house. The installer inspects the system and finds that the effluent filter is
clogged with solids. What is the MOST appropriate recommendation for the homeowner to
prevent this issue from recurring?
A. Remove the effluent filter entirely to prevent future clogs.
B. Install a larger septic tank to handle more solids before they reach the filter.
C. Have the septic tank pumped and clean the effluent filter regularly as part of routine
maintenance.
D. Add chemical additives to the system to break down solids and prevent filter clogging.
Correct Answer: C
Mississippi Individual Onsite Wastewater
Installer -Licensing Exam QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES JUST
RELEASED
Mississippi Individual Onsite Wastewater Installer Licensing Exam
EXAM COVERAGE (Point Form)
• Onsite Wastewater System Regulations & Installer Responsibilities (Core Exam
Area)
• Site Evaluation & Soil Assessment
• Septic Tanks & Pretreatment Components
• Soil Absorption Systems & Drainfields
• Onsite Wastewater System Components
• Installation Procedures & Construction Standards
• System Operation, Maintenance & Troubleshooting
• Safety, Environmental Protection & Public Health
• Inspection, Documentation & Code Compliance
QUESTIONS 1-300
1. A homeowner in Mississippi is planning to install a new onsite wastewater system on a
property with a seasonal high water table at 18 inches below the surface. According to
MSDH regulations, what is the minimum required depth between the bottom of the
drainfield trench and the seasonal high water table to ensure proper treatment and prevent
groundwater contamination?
, Page 2 of 227
A. 6 inches, which is sufficient for most soil types and seasonal conditions.
B. 12 inches, because this provides adequate separation for treatment in all soils.
C. 24 inches, which is the minimum vertical separation required by MSDH regulations to protect
groundwater.
D. 36 inches, which ensures complete treatment even during periods of heavy rainfall.
Correct Answer: C
Rationale: Mississippi State Department of Health regulations require a minimum vertical
separation of 24 inches between the bottom of the drainfield trench and the seasonal high water
table . This separation is essential to ensure adequate soil treatment of effluent before it reaches
groundwater.
2. A certified installer is preparing to install a septic tank on a property with a high water
table. Which of the following is the MOST critical consideration to prevent the tank from
floating out of the ground during installation and operation?
A. The tank must be filled with water immediately after placement to provide counterweight
against buoyancy forces.
B. The tank must be placed on a compacted gravel base to provide stability.
, Page 3 of 227
C. The tank must be anchored to a concrete base or have anti-flotation devices installed to
prevent buoyancy.
D. The tank must be backfilled with sand to allow drainage and prevent flotation.
Correct Answer: C
Rationale: Septic tanks must be anchored to a concrete base or have anti-flotation devices
installed in high water table areas . Empty tanks can float out of the ground when groundwater
rises, causing damage to the system.
3. During a site evaluation, an installer observes that the soil has a high clay content and
slow percolation rate. According to MSDH regulations, what is the MOST appropriate
action for designing the onsite wastewater system?
A. Install a conventional septic tank and drainfield without modification, as clay soils provide
good filtration.
B. Increase the size of the drainfield to compensate for the slow percolation rate and consider
alternative system design.
C. Install a cesspool instead of a septic tank because clay soils are suitable for cesspool
construction.
, Page 4 of 227
D. Recommend that the homeowner abandon the site and purchase a different property for
development.
Correct Answer: B
Rationale: High clay content and slow percolation rates require larger drainfields or alternative
system designs to ensure adequate treatment . The installer must evaluate site conditions and
design a system that meets MSDH requirements.
4. A homeowner reports that their septic system is experiencing backups and slow drainage
throughout the house. The installer inspects the system and finds that the effluent filter is
clogged with solids. What is the MOST appropriate recommendation for the homeowner to
prevent this issue from recurring?
A. Remove the effluent filter entirely to prevent future clogs.
B. Install a larger septic tank to handle more solids before they reach the filter.
C. Have the septic tank pumped and clean the effluent filter regularly as part of routine
maintenance.
D. Add chemical additives to the system to break down solids and prevent filter clogging.
Correct Answer: C
