Florida (FL) Septic Tank Contractor Practice
Exam 2026
Question 1
What is the primary purpose of a septic tank in an onsite sewage treatment and disposal
system?
A) To disinfect wastewater before it reaches the drainfield
B) To store and partially treat wastewater by allowing solids to settle and scum to
float
C) To pump wastewater to a municipal sewer system
D) To filter drinking water for household use
Rationale: The septic tank allows solids to settle to the bottom (sludge) and oils/greases to
float to the top (scum), providing primary treatment through anaerobic decomposition
before the effluent moves to the drainfield for further treatment.
Question 2
What is the minimum required horizontal setback distance between a standard
residential septic tank and a private potable water well in Florida?
A) 50 feet
B) 75 feet
C) 100 feet
D) 150 feet
Rationale: Under Chapter 64E-6, Florida Administrative Code (F.A.C.), any component of
an Onsite Sewage Treatment and Disposal System (OSTDS) must maintain a minimum
,75-foot horizontal separation from private potable water wells to prevent biological and
chemical groundwater contamination.
Question 3
According to Chapter 64E-6, F.A.C., what is the minimum liquid capacity required for a
septic tank serving a 3-bedroom single-family home with a heated square footage
under 2,250 sq. ft.?
A) 750 gallons
B) 900 gallons
C) 1,000 gallons
D) 1,200 gallons
Rationale: Standard single-family residences with 1 to 4 bedrooms or a total heated area
up to 2,250 square feet require a base minimum liquid capacity of 1,000 gallons to
provide adequate hydraulic retention time for proper wastewater treatment.
Question 4
Which Florida agency primarily regulates onsite sewage treatment systems and issues
permits for septic tank installations?
A) Florida Department of Environmental Protection (DEP)
B) Florida Department of Health (DOH)
C) Florida Department of Agriculture and Consumer Services
D) Florida Department of Transportation
Rationale: The Florida Department of Health oversees septic system permitting, inspection,
and regulation for most counties in Florida. However, in some counties, the Department of
Environmental Protection (DEP) has assumed this role.
Question 5
,To achieve proper treatment of effluent before it reaches groundwater, Florida
regulations require a minimum vertical separation of how many inches of unsaturated
soil beneath the bottom of the drainfield?
A) 12 inches
B) 18 inches
C) 24 inches
D) 36 inches
Rationale: Florida's porous geology requires a minimum of 24 inches of unsaturated soil
between the bottom of the drainfield absorption surface and the seasonal high-water table
(SHWT) to ensure sufficient natural filtration of pathogens and treatment of effluent.
Question 6
What is the main purpose of performing a soil percolation (perc) test during a site
evaluation for a septic system?
A) To determine the chemical composition of the soil
B) To assess the soil's ability to absorb effluent
C) To measure the depth of groundwater
D) To evaluate vegetation growth on the property
Rationale: A soil percolation test determines how quickly the soil absorbs water, which is
crucial for sizing and designing an appropriate septic system. The perc rate directly
impacts drainfield sizing and system selection.
Question 7
What is the primary function of a drainfield (leach field) in a septic system?
A) To store wastewater until it can be pumped out
B) To treat and disperse effluent into the soil for final treatment
C) To pump wastewater uphill to the septic tank
D) To separate grease and oils from wastewater
, Rationale: The drainfield allows effluent to percolate through the soil, where natural
biological and chemical processes provide final treatment before the water reaches the
groundwater table.
Question 8
Which component in a conventional septic system is primarily responsible for the initial
separation of solids from wastewater?
A) Septic tank
B) Drainfield
C) Distribution box
D) Effluent filter
Rationale: The septic tank is designed to allow solids to settle to the bottom (forming
sludge) and scum to float to the top, providing primary separation before the effluent
flows to the drainfield.
Question 9
Which soil type has the fastest percolation rate, making it most suitable for drainfields?
A) Clay
B) Silt
C) Sand
D) Loam
Rationale: Sandy soils have large pore spaces that allow water to percolate quickly,
reducing the risk of effluent backup and providing good drainage. This makes sandy soils
the most suitable for drainfield absorption.
Question 10
Exam 2026
Question 1
What is the primary purpose of a septic tank in an onsite sewage treatment and disposal
system?
A) To disinfect wastewater before it reaches the drainfield
B) To store and partially treat wastewater by allowing solids to settle and scum to
float
C) To pump wastewater to a municipal sewer system
D) To filter drinking water for household use
Rationale: The septic tank allows solids to settle to the bottom (sludge) and oils/greases to
float to the top (scum), providing primary treatment through anaerobic decomposition
before the effluent moves to the drainfield for further treatment.
Question 2
What is the minimum required horizontal setback distance between a standard
residential septic tank and a private potable water well in Florida?
A) 50 feet
B) 75 feet
C) 100 feet
D) 150 feet
Rationale: Under Chapter 64E-6, Florida Administrative Code (F.A.C.), any component of
an Onsite Sewage Treatment and Disposal System (OSTDS) must maintain a minimum
,75-foot horizontal separation from private potable water wells to prevent biological and
chemical groundwater contamination.
Question 3
According to Chapter 64E-6, F.A.C., what is the minimum liquid capacity required for a
septic tank serving a 3-bedroom single-family home with a heated square footage
under 2,250 sq. ft.?
A) 750 gallons
B) 900 gallons
C) 1,000 gallons
D) 1,200 gallons
Rationale: Standard single-family residences with 1 to 4 bedrooms or a total heated area
up to 2,250 square feet require a base minimum liquid capacity of 1,000 gallons to
provide adequate hydraulic retention time for proper wastewater treatment.
Question 4
Which Florida agency primarily regulates onsite sewage treatment systems and issues
permits for septic tank installations?
A) Florida Department of Environmental Protection (DEP)
B) Florida Department of Health (DOH)
C) Florida Department of Agriculture and Consumer Services
D) Florida Department of Transportation
Rationale: The Florida Department of Health oversees septic system permitting, inspection,
and regulation for most counties in Florida. However, in some counties, the Department of
Environmental Protection (DEP) has assumed this role.
Question 5
,To achieve proper treatment of effluent before it reaches groundwater, Florida
regulations require a minimum vertical separation of how many inches of unsaturated
soil beneath the bottom of the drainfield?
A) 12 inches
B) 18 inches
C) 24 inches
D) 36 inches
Rationale: Florida's porous geology requires a minimum of 24 inches of unsaturated soil
between the bottom of the drainfield absorption surface and the seasonal high-water table
(SHWT) to ensure sufficient natural filtration of pathogens and treatment of effluent.
Question 6
What is the main purpose of performing a soil percolation (perc) test during a site
evaluation for a septic system?
A) To determine the chemical composition of the soil
B) To assess the soil's ability to absorb effluent
C) To measure the depth of groundwater
D) To evaluate vegetation growth on the property
Rationale: A soil percolation test determines how quickly the soil absorbs water, which is
crucial for sizing and designing an appropriate septic system. The perc rate directly
impacts drainfield sizing and system selection.
Question 7
What is the primary function of a drainfield (leach field) in a septic system?
A) To store wastewater until it can be pumped out
B) To treat and disperse effluent into the soil for final treatment
C) To pump wastewater uphill to the septic tank
D) To separate grease and oils from wastewater
, Rationale: The drainfield allows effluent to percolate through the soil, where natural
biological and chemical processes provide final treatment before the water reaches the
groundwater table.
Question 8
Which component in a conventional septic system is primarily responsible for the initial
separation of solids from wastewater?
A) Septic tank
B) Drainfield
C) Distribution box
D) Effluent filter
Rationale: The septic tank is designed to allow solids to settle to the bottom (forming
sludge) and scum to float to the top, providing primary separation before the effluent
flows to the drainfield.
Question 9
Which soil type has the fastest percolation rate, making it most suitable for drainfields?
A) Clay
B) Silt
C) Sand
D) Loam
Rationale: Sandy soils have large pore spaces that allow water to percolate quickly,
reducing the risk of effluent backup and providing good drainage. This makes sandy soils
the most suitable for drainfield absorption.
Question 10
