Commercial Septic System Installer Exam – 2025/2026
Updated Study Guide & Practice Questions | 100% Pass
Guarantee
All tanks must have: - correct answer2 compartments
All tanks whether pre-manufactured or constructed on site shall be constructed so that
the length is ___________ compared to the width. - correct answerat least one and
one- half (1 1/2) times... "to the width."
Septic Tanks may be made of: - correct answerConcrete, Plastic, fiberglass, or other
materials as approved by the department.
Tank compartment partitions will be located: - correct answerNot 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 is positioned below the liquid surface with a
_____________________________. - correct answerMinimum 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 answer66 inches
True or False: Walls and bottom of poured-in-place septic tanks must be reinforced. -
correct answerTrue
How can a Septic tank be reinforced? - correct answersix inch by 6 inch (6"x6") No.10
gage welded steel reinforcing wire OR fibrous reinforcing material conforming to ASTM
specifications for such materials.
How must Tank Lids be Reinforced? - correct answerusing three-eights steel reinforcing
rods (rebar) which shall be spaced twelve inches (12") on center each way extending a
minimum of two and one half (2 1/2") inches and a maximum of three (3") from the
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 subjected. - correct answer150
True or False: Walls, bottoms, and lids of poured-in-place septic tanks should have a
minimum thickness of four inches (4"). - correct answerTrue
, Tank lids shall be constructed in ______________________ pieces and shall have
securable, removable access openings located so that the inlet and outlet tees can be
________________________________. - correct answerone or two,
readily accessed.
Access opening shall have a minimum of _________________ and maximum of
___________________ free space. - correct answerMinimum: 15"
Maximum: 24"
Tanks with more than 12 inches of cover must extend access openings to within ______
inches of the ground surface. - correct answer12
All tanks shall be equipped with ________________________________ rated or
equivalent tees at the inlet and outlet ends of the tank. - correct answerFour inch (4")
PVC, ASTM 3034
Tees shall be constructed so they extend into the liquid a minimum of
____________________ and a maximum of __________________ of the liquid depth
of the tank. - correct answerMin: 25%
Max: 50%
The invert of the outlet tee shall be located _______________ inches below the invert
of the inlet tee. - correct answertwo inches
__________________ tees shall be equipped with an approved effluent filter. - correct
answerOutlet
Concrete used for poured-in-place or pre-cast septic tanks shall have a minimum
________________________. - correct answer28 day compressive strength of 4000
pounds per square inch.
When pouring concrete, care should be taken to assure such operations are not done
during freezing or other wise inclement periods because
_________________________________. - correct answerit could damage the integrity
of the finished product.
the finished poured concrete product should have what texture and finish? - correct
answersmooth homogeneous consistency and finish.
True of False: Vibrating the forms or mix may be helpful in eliminating "honey combing"
or "bridging" in the finished product. - correct answerTrue
Who's responsibility is it to assure the quality of the finished product? - correct
answerThe on-site sewage contractor.
Updated Study Guide & Practice Questions | 100% Pass
Guarantee
All tanks must have: - correct answer2 compartments
All tanks whether pre-manufactured or constructed on site shall be constructed so that
the length is ___________ compared to the width. - correct answerat least one and
one- half (1 1/2) times... "to the width."
Septic Tanks may be made of: - correct answerConcrete, Plastic, fiberglass, or other
materials as approved by the department.
Tank compartment partitions will be located: - correct answerNot 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 is positioned below the liquid surface with a
_____________________________. - correct answerMinimum 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 answer66 inches
True or False: Walls and bottom of poured-in-place septic tanks must be reinforced. -
correct answerTrue
How can a Septic tank be reinforced? - correct answersix inch by 6 inch (6"x6") No.10
gage welded steel reinforcing wire OR fibrous reinforcing material conforming to ASTM
specifications for such materials.
How must Tank Lids be Reinforced? - correct answerusing three-eights steel reinforcing
rods (rebar) which shall be spaced twelve inches (12") on center each way extending a
minimum of two and one half (2 1/2") inches and a maximum of three (3") from the
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 subjected. - correct answer150
True or False: Walls, bottoms, and lids of poured-in-place septic tanks should have a
minimum thickness of four inches (4"). - correct answerTrue
, Tank lids shall be constructed in ______________________ pieces and shall have
securable, removable access openings located so that the inlet and outlet tees can be
________________________________. - correct answerone or two,
readily accessed.
Access opening shall have a minimum of _________________ and maximum of
___________________ free space. - correct answerMinimum: 15"
Maximum: 24"
Tanks with more than 12 inches of cover must extend access openings to within ______
inches of the ground surface. - correct answer12
All tanks shall be equipped with ________________________________ rated or
equivalent tees at the inlet and outlet ends of the tank. - correct answerFour inch (4")
PVC, ASTM 3034
Tees shall be constructed so they extend into the liquid a minimum of
____________________ and a maximum of __________________ of the liquid depth
of the tank. - correct answerMin: 25%
Max: 50%
The invert of the outlet tee shall be located _______________ inches below the invert
of the inlet tee. - correct answertwo inches
__________________ tees shall be equipped with an approved effluent filter. - correct
answerOutlet
Concrete used for poured-in-place or pre-cast septic tanks shall have a minimum
________________________. - correct answer28 day compressive strength of 4000
pounds per square inch.
When pouring concrete, care should be taken to assure such operations are not done
during freezing or other wise inclement periods because
_________________________________. - correct answerit could damage the integrity
of the finished product.
the finished poured concrete product should have what texture and finish? - correct
answersmooth homogeneous consistency and finish.
True of False: Vibrating the forms or mix may be helpful in eliminating "honey combing"
or "bridging" in the finished product. - correct answerTrue
Who's responsibility is it to assure the quality of the finished product? - correct
answerThe on-site sewage contractor.
