Commercial Septic System Installer Exam
Questions with Correct Answers 2026
All tanks must have: - CORRECT ANSWER -2 compartments
All tanks whether pre-manufactured or constructed on site shall be constructed so that the length
is co mpared to the width. - CORRECT ANSWER -at least one and one-
half (1 1/2) times... "to the width."
Septic Tanks may be made of: - CORRECT ANSWER -
Concrete, Plastic, fiberglass, or other materials asBapproved by the department.
Tank compartment partitions will be located: - CORRECT ANSWER -Not less than two-
thirds or more than three-fourths the Length of the tank from the Inlet end.
Compartment partitions will be constructed so a pass-
thru hole or slot equal to or greater than the diameter of the inlet pipe isBpositioned below the l
iquid surface with a . - CORRECT ANSWER -
Minimum 25% to a maximum of 50% of the total liquid depth.
Total liquid depth for larger poured-in-
place tanks shall have a maximum of inches - CORRECT ANSWER -66 inches
True or False: Walls and bottom of poured-in-place septic tanks must be reinforced. -
CORRECT ANSWER -True
How can a Septic tank be reinforced? - CORRECT ANSWER -
six inch by 6 inch (6"x6") No.10 gage welded steel reinforcing wire OR fibrous reinforcing materi
al conforming to ASTM specifications for such materials.
, How must Tank Lids be Reinforced? - CORRECT ANSWER -using three-
eights steel reinforcing rods (rebar) which shall be spaced twelve inches (12") on center each wa
y extendingBa minimum of two and one half (2 1/2") inches and a maximum of three (3") from t
he outside edge of the tank lid.
In general, the tank must be able to withstand a uniform live load of
pounds per square foot in addition to all loads to which an underground tank is normally subjec
ted. - CORRECT ANSWER -150
True or False: Walls, bottoms, and lids of poured-in-
place septic tanks should have a minimum thickness of four inches (4"). - CORRECT ANSWER -
True
Tank lids shall be constructed in pieces and shall have securable, re
movable access openings located so that the inlet and outlet tees can be
. - CORRECT ANSWER -one or two,
readily accessed.
Access opening shall have a minimum of and maximum of
free space. - CORRECT ANSWER -Minimum: 15"
Maximum: 24"
Tanks with more than 12 inches of cover must extend access openings to within inches
of the ground surface. - CORRECT ANSWER -12
All tanks shall be equipped with rated or equivalent tees
at the inlet and outlet ends of the tank. - CORRECT ANSWER -Four inch (4") PVC, ASTM 3034
Questions with Correct Answers 2026
All tanks must have: - CORRECT ANSWER -2 compartments
All tanks whether pre-manufactured or constructed on site shall be constructed so that the length
is co mpared to the width. - CORRECT ANSWER -at least one and one-
half (1 1/2) times... "to the width."
Septic Tanks may be made of: - CORRECT ANSWER -
Concrete, Plastic, fiberglass, or other materials asBapproved by the department.
Tank compartment partitions will be located: - CORRECT ANSWER -Not less than two-
thirds or more than three-fourths the Length of the tank from the Inlet end.
Compartment partitions will be constructed so a pass-
thru hole or slot equal to or greater than the diameter of the inlet pipe isBpositioned below the l
iquid surface with a . - CORRECT ANSWER -
Minimum 25% to a maximum of 50% of the total liquid depth.
Total liquid depth for larger poured-in-
place tanks shall have a maximum of inches - CORRECT ANSWER -66 inches
True or False: Walls and bottom of poured-in-place septic tanks must be reinforced. -
CORRECT ANSWER -True
How can a Septic tank be reinforced? - CORRECT ANSWER -
six inch by 6 inch (6"x6") No.10 gage welded steel reinforcing wire OR fibrous reinforcing materi
al conforming to ASTM specifications for such materials.
, How must Tank Lids be Reinforced? - CORRECT ANSWER -using three-
eights steel reinforcing rods (rebar) which shall be spaced twelve inches (12") on center each wa
y extendingBa minimum of two and one half (2 1/2") inches and a maximum of three (3") from t
he outside edge of the tank lid.
In general, the tank must be able to withstand a uniform live load of
pounds per square foot in addition to all loads to which an underground tank is normally subjec
ted. - CORRECT ANSWER -150
True or False: Walls, bottoms, and lids of poured-in-
place septic tanks should have a minimum thickness of four inches (4"). - CORRECT ANSWER -
True
Tank lids shall be constructed in pieces and shall have securable, re
movable access openings located so that the inlet and outlet tees can be
. - CORRECT ANSWER -one or two,
readily accessed.
Access opening shall have a minimum of and maximum of
free space. - CORRECT ANSWER -Minimum: 15"
Maximum: 24"
Tanks with more than 12 inches of cover must extend access openings to within inches
of the ground surface. - CORRECT ANSWER -12
All tanks shall be equipped with rated or equivalent tees
at the inlet and outlet ends of the tank. - CORRECT ANSWER -Four inch (4") PVC, ASTM 3034
