NEW YORK MASTER PLUMBER LICENSING
EXAM – PRACTICE QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A
1. The minimum size of a house sewer connecting to a public sewer shall be
A. 2 inches
B. 3 inches
C. 4 inches
D. 6 inches
The NYC Plumbing Code requires a minimum 4-inch house sewer connection
to a public sewer.
2. The trap seal depth shall not be less than
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
Trap seals must be at least 2 inches to prevent sewer gas entry while
maintaining proper drainage.
3. The maximum horizontal distance between a trap and its vent for a 2-inch
pipe is
A. 2 feet
B. 5 feet
C. 6 feet
D. 8 feet
, For a 2-inch diameter trap arm, the developed length to the vent cannot
exceed 5 feet.
4. A building drain is defined as the lowest horizontal piping that
A. Receives discharge from soil, waste, and other drainage pipes inside the
building
B. Connects the building sewer to the street main
C. Vents the entire plumbing system
D. Connects fixtures directly
This is the correct definition per NYC Plumbing Code Section 202.
5. The minimum size of a vent for a water closet with a 3-inch waste is
A. 1 inch
B. 1½ inches
C. 2 inches
D. 3 inches
The vent size must be at least 2 inches for a 3-inch waste line.
6. The cleanout for a horizontal drainage pipe shall be located
A. At the end of the run
B. At every 5 feet
C. At the midpoint of the run
D. Only at the fixture
Cleanouts are required at the end of each horizontal drainage line for
maintenance.
7. The slope for a 4-inch building drain should be
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
The standard slope ensures self-cleansing velocity and proper flow.
8. The minimum cover over a building sewer buried in soil is
A. 6 inches
, B. 12 inches
C. 18 inches
D. 24 inches
NYC Plumbing Code requires at least 12 inches of cover for protection from
damage.
9. A vent stack is defined as
A. The vertical vent pipe installed primarily for providing circulation of air
to and from the drainage system
B. A pipe connecting a fixture trap to the vent
C. A soil stack
D. A waste stack
This definition comes directly from the plumbing code.
10. Stormwater piping must be tested using
A. Water test only
B. Air test only
C. Water or air test
D. Smoke test
Either method is acceptable as long as it meets the code’s leak-proof
standards.
11. A plumbing permit is required for
A. Painting pipes
B. Replacing faucets
C. Installing new drainage piping
D. Cleaning a drain
Permits are needed for new plumbing installations or alterations.
12. The air test on drainage systems shall be applied with a pressure of
A. 3 psi
B. 4 psi
C. 5 psi
D. 10 psi
Five pounds per square inch is required for a minimum of 15 minutes.
EXAM – PRACTICE QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A
1. The minimum size of a house sewer connecting to a public sewer shall be
A. 2 inches
B. 3 inches
C. 4 inches
D. 6 inches
The NYC Plumbing Code requires a minimum 4-inch house sewer connection
to a public sewer.
2. The trap seal depth shall not be less than
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
Trap seals must be at least 2 inches to prevent sewer gas entry while
maintaining proper drainage.
3. The maximum horizontal distance between a trap and its vent for a 2-inch
pipe is
A. 2 feet
B. 5 feet
C. 6 feet
D. 8 feet
, For a 2-inch diameter trap arm, the developed length to the vent cannot
exceed 5 feet.
4. A building drain is defined as the lowest horizontal piping that
A. Receives discharge from soil, waste, and other drainage pipes inside the
building
B. Connects the building sewer to the street main
C. Vents the entire plumbing system
D. Connects fixtures directly
This is the correct definition per NYC Plumbing Code Section 202.
5. The minimum size of a vent for a water closet with a 3-inch waste is
A. 1 inch
B. 1½ inches
C. 2 inches
D. 3 inches
The vent size must be at least 2 inches for a 3-inch waste line.
6. The cleanout for a horizontal drainage pipe shall be located
A. At the end of the run
B. At every 5 feet
C. At the midpoint of the run
D. Only at the fixture
Cleanouts are required at the end of each horizontal drainage line for
maintenance.
7. The slope for a 4-inch building drain should be
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
The standard slope ensures self-cleansing velocity and proper flow.
8. The minimum cover over a building sewer buried in soil is
A. 6 inches
, B. 12 inches
C. 18 inches
D. 24 inches
NYC Plumbing Code requires at least 12 inches of cover for protection from
damage.
9. A vent stack is defined as
A. The vertical vent pipe installed primarily for providing circulation of air
to and from the drainage system
B. A pipe connecting a fixture trap to the vent
C. A soil stack
D. A waste stack
This definition comes directly from the plumbing code.
10. Stormwater piping must be tested using
A. Water test only
B. Air test only
C. Water or air test
D. Smoke test
Either method is acceptable as long as it meets the code’s leak-proof
standards.
11. A plumbing permit is required for
A. Painting pipes
B. Replacing faucets
C. Installing new drainage piping
D. Cleaning a drain
Permits are needed for new plumbing installations or alterations.
12. The air test on drainage systems shall be applied with a pressure of
A. 3 psi
B. 4 psi
C. 5 psi
D. 10 psi
Five pounds per square inch is required for a minimum of 15 minutes.
