New York Plumber Licensing Exam
With Actual Questions & Verified
Answers,Plus Rationales/Expert
Verified For Guaranteed Pass Graded
A+/2026 /Latest Update/Instant
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1. The minimum slope required for a 3-inch horizontal drain is:
A) 1/8 inch per foot
B) 1/4 inch per foot
C) 3/8 inch per foot
D) 1/2 inch per foot
Rationale: The New York Plumbing Code requires a 1/4 inch per foot
slope for 2½–3 inch drains to ensure proper flow velocity.
2. The minimum size of a vent pipe serving a 4-inch soil stack is:
A) 2 inches
B) 3 inches
C) 1½ inches
D) 4 inches
Rationale: A 3-inch vent is required for a 4-inch stack to prevent trap seal
loss due to air pressure changes.
3. The maximum horizontal distance between a trap and its vent for a 2-
inch pipe is:
A) 2 feet
B) 3 feet
C) 5 feet
D) 8 feet
, Rationale: For a 2-inch pipe, the maximum developed length from the
trap weir to the vent is 5 feet.
4. What is the minimum air gap required for a fixture outlet below a flood-
level rim?
A) 1 inch
B) Twice the diameter of the outlet pipe
C) ¾ inch
D) 1½ inches
Rationale: The minimum air gap must be twice the effective diameter of
the outlet to prevent backflow.
5. A cleanout is required for every horizontal drainage pipe:
A) Every 10 feet
B) Every 100 feet
C) Every 50 feet
D) At each change of direction
Rationale: Cleanouts must be located every 100 feet in horizontal
drainage piping per NYC Plumbing Code.
6. Which type of joint is approved for joining cast iron soil pipe in a building
drain?
A) Threaded joint
B) Brazed joint
C) No-hub (mechanical) joint
D) Compression joint
Rationale: No-hub mechanical joints are standard for joining cast iron
soil pipes inside buildings.
7. The minimum trap seal depth is:
A) 1 inch
B) 3 inches
C) 2 inches
D) 4 inches
Rationale: The trap seal must be at least 2 inches to prevent sewer gas
escape while maintaining water seal.
, 8. What is the minimum required pressure test for a drain-waste-vent
(DWV) system using water?
A) 3 psi for 5 minutes
B) 5 psi for 10 minutes
C) 10 feet head of water for 15 minutes
D) 15 psi for 15 minutes
Rationale: A water test using a 10-foot head of water for 15 minutes is
required for DWV systems.
9. The minimum size of a water service pipe to a single-family dwelling is:
A) ½ inch
B) ¾ inch
C) 1 inch
D) 1½ inches
Rationale: A minimum of ¾ inch ensures sufficient flow and pressure for a
typical single-family home.
10.A vent must terminate how far above a roof used for occupancy?
A) 6 inches
B) 12 inches
C) 18 inches
D) 7 feet
Rationale: When a roof is used for occupancy, vents must terminate at
least 7 feet above to avoid exposure to fumes.
11.The minimum trap arm length for a 1½-inch pipe is:
A) 3 inches
B) 3 feet, 6 inches
C) 2 feet
D) 5 feet
Rationale: A 1½-inch trap arm may be up to 3 feet 6 inches in developed
length.
12.Which of the following materials is NOT approved for hot water
distribution piping?
A) Copper
With Actual Questions & Verified
Answers,Plus Rationales/Expert
Verified For Guaranteed Pass Graded
A+/2026 /Latest Update/Instant
Download Pdf
1. The minimum slope required for a 3-inch horizontal drain is:
A) 1/8 inch per foot
B) 1/4 inch per foot
C) 3/8 inch per foot
D) 1/2 inch per foot
Rationale: The New York Plumbing Code requires a 1/4 inch per foot
slope for 2½–3 inch drains to ensure proper flow velocity.
2. The minimum size of a vent pipe serving a 4-inch soil stack is:
A) 2 inches
B) 3 inches
C) 1½ inches
D) 4 inches
Rationale: A 3-inch vent is required for a 4-inch stack to prevent trap seal
loss due to air pressure changes.
3. The maximum horizontal distance between a trap and its vent for a 2-
inch pipe is:
A) 2 feet
B) 3 feet
C) 5 feet
D) 8 feet
, Rationale: For a 2-inch pipe, the maximum developed length from the
trap weir to the vent is 5 feet.
4. What is the minimum air gap required for a fixture outlet below a flood-
level rim?
A) 1 inch
B) Twice the diameter of the outlet pipe
C) ¾ inch
D) 1½ inches
Rationale: The minimum air gap must be twice the effective diameter of
the outlet to prevent backflow.
5. A cleanout is required for every horizontal drainage pipe:
A) Every 10 feet
B) Every 100 feet
C) Every 50 feet
D) At each change of direction
Rationale: Cleanouts must be located every 100 feet in horizontal
drainage piping per NYC Plumbing Code.
6. Which type of joint is approved for joining cast iron soil pipe in a building
drain?
A) Threaded joint
B) Brazed joint
C) No-hub (mechanical) joint
D) Compression joint
Rationale: No-hub mechanical joints are standard for joining cast iron
soil pipes inside buildings.
7. The minimum trap seal depth is:
A) 1 inch
B) 3 inches
C) 2 inches
D) 4 inches
Rationale: The trap seal must be at least 2 inches to prevent sewer gas
escape while maintaining water seal.
, 8. What is the minimum required pressure test for a drain-waste-vent
(DWV) system using water?
A) 3 psi for 5 minutes
B) 5 psi for 10 minutes
C) 10 feet head of water for 15 minutes
D) 15 psi for 15 minutes
Rationale: A water test using a 10-foot head of water for 15 minutes is
required for DWV systems.
9. The minimum size of a water service pipe to a single-family dwelling is:
A) ½ inch
B) ¾ inch
C) 1 inch
D) 1½ inches
Rationale: A minimum of ¾ inch ensures sufficient flow and pressure for a
typical single-family home.
10.A vent must terminate how far above a roof used for occupancy?
A) 6 inches
B) 12 inches
C) 18 inches
D) 7 feet
Rationale: When a roof is used for occupancy, vents must terminate at
least 7 feet above to avoid exposure to fumes.
11.The minimum trap arm length for a 1½-inch pipe is:
A) 3 inches
B) 3 feet, 6 inches
C) 2 feet
D) 5 feet
Rationale: A 1½-inch trap arm may be up to 3 feet 6 inches in developed
length.
12.Which of the following materials is NOT approved for hot water
distribution piping?
A) Copper
