Master Plumber Licensing Exam Study Guide:
Comprehensive Question Bank with Correct
Answers and Detailed Rationales | Latest
Update 2026/2027
QUESTION 1
The Plumbing Code is used to:
A. enforce the law
B. confuse the plumber
C. explain why plumbing installations may vary
D. explain why minor changes from the basic rules are acceptable
Correct Answer: A
Rationale: The provisions of the following chapters and sections shall constitute and be
known and cited as the Code (law). Plumbing codes are laws adopted by local and state
authorities. Violating any provision of these codes is considered a misdemeanor,
punishable by a fine or imprisonment upon conviction.
QUESTION 2
According to the Code, one of the following shall not be used in a drainage system:
A. a 3-inch short sweep
B. a fitting having 60-degree branches
C. a double sanitary tee
D. a straight tee branch
Correct Answer: D
Rationale: A straight tee branch shall not be used as a drainage fitting. No tee branch
shall be used as a drainage fitting.
QUESTION 3
According to the Code, the drainage system or any part thereof shall not be covered until:
A. after a plumbing inspector has been called
B. it has been tested
C. it has been inspected
D. it has been approved
Correct Answer: D
Rationale: The plumbing system or any part thereof shall not be covered until approved.
,No plumbing or drainage system or part thereof shall be covered until it has been
accepted.
QUESTION 4
According to the Code, it shall be the duty and responsibility of the _______ to determine if
the plumbing has been inspected before it is covered or concealed.
A. general contractor
B. permit holder
C. plumbing inspector
D. building and zoning record control branch
Correct Answer: B
Rationale: Permit holder is responsible for all plumbing work installed. Permit holder is
responsible for work performed.
QUESTION 5
Every plumbing fixture directly connected to the drainage system, according to the Code, shall:
A. have an overflow
B. be maintained in a sanitary manner
C. have hot and cold water
D. be equipped with a water-seal trap
Correct Answer: D
Rationale: Be equipped with a water-seal trap. Be trapped by an approved type water-
seal trap.
QUESTION 6
According to the Code, drainage systems were tested for tightness and for inspection shall be
tested with no less than a _______ head of water.
A. 6-foot
B. 8-foot
C. 10-foot
D. 12-foot
Correct Answer: C
Rationale: No section shall be tested with less than a 10-foot head of water.
,QUESTION 7
According to the Code, when notching the ends of joints to install water piping, the depth of
the notches shall not exceed _______ of the depth of the joints.
A. 1/16
B. 1/32
C. 1/8
D. 1/4
Correct Answer: D
Rationale: When notching the ends of joints, the depth shall not exceed 1/4 the depth of
the joints.
QUESTION 8
The Code requires that drainage fittings have threads that are tapped to allow for:
A. full thread engagement
B. grade
C. simple adjustment
D. pipe expansion
Correct Answer: B
Rationale: The threads of drainage fittings shall be tapped so as to allow for grade.
QUESTION 9
The Code requires that when a water service pipe is installed in the same trench with a building
sewer, there must be a minimum separation of _______ inches.
A. 6
B. 10
C. 12
D. 18
Correct Answer: C
Rationale: The bottom of the water service pipe, at all points, shall be at least 12 inches
above the top of the sewer pipe.
QUESTION 10
The Code requires that sewage or other waste from a plumbing system be _______ before it is
discharged into any waterway.
A. discharged through a settling tank
B. treated with Clorox
C. rendered innocuous
D. determined detrimental
Correct Answer: C
Rationale: Sewage or other waste must first be rendered innocuous.
, QUESTION 11
According to the Plumbing Code, _______ fixture unit(s) flow rate shall be deemed to be 1
cubic foot per minute.
A. 1
B. 2
C. 3
D. 4
Correct Answer: A
Rationale: A fixture unit flow rate shall be deemed to be 1 cubic foot of water per minute.
One fixture unit discharge capacity shall be deemed to be 7½ gallons per minute.
QUESTION 12
According to the Code, 2-inch copper tubing installed horizontally must be supported at
distances of not less than _______ feet.
A. 4
B. 6
C. 8
D. 10
Correct Answer: D
Rationale: Copper tubing shall be supported at approximately 10-foot intervals for
piping 2 inches and larger.
QUESTION 13
A single-family house, connected to a public sewer, may discharge all but one of the following
substances through its drainage system without violating the Code:
A. human excrement
B. potable water
C. fireplace ashes
D. clothes washer water
Correct Answer: C
Rationale: No substance which will clog the pipes shall be allowed to enter the building
drainage system. It shall be unlawful for any person to deposit, into any plumbing fixture
which is connected to any public sewer, any ashes.
Comprehensive Question Bank with Correct
Answers and Detailed Rationales | Latest
Update 2026/2027
QUESTION 1
The Plumbing Code is used to:
A. enforce the law
B. confuse the plumber
C. explain why plumbing installations may vary
D. explain why minor changes from the basic rules are acceptable
Correct Answer: A
Rationale: The provisions of the following chapters and sections shall constitute and be
known and cited as the Code (law). Plumbing codes are laws adopted by local and state
authorities. Violating any provision of these codes is considered a misdemeanor,
punishable by a fine or imprisonment upon conviction.
QUESTION 2
According to the Code, one of the following shall not be used in a drainage system:
A. a 3-inch short sweep
B. a fitting having 60-degree branches
C. a double sanitary tee
D. a straight tee branch
Correct Answer: D
Rationale: A straight tee branch shall not be used as a drainage fitting. No tee branch
shall be used as a drainage fitting.
QUESTION 3
According to the Code, the drainage system or any part thereof shall not be covered until:
A. after a plumbing inspector has been called
B. it has been tested
C. it has been inspected
D. it has been approved
Correct Answer: D
Rationale: The plumbing system or any part thereof shall not be covered until approved.
,No plumbing or drainage system or part thereof shall be covered until it has been
accepted.
QUESTION 4
According to the Code, it shall be the duty and responsibility of the _______ to determine if
the plumbing has been inspected before it is covered or concealed.
A. general contractor
B. permit holder
C. plumbing inspector
D. building and zoning record control branch
Correct Answer: B
Rationale: Permit holder is responsible for all plumbing work installed. Permit holder is
responsible for work performed.
QUESTION 5
Every plumbing fixture directly connected to the drainage system, according to the Code, shall:
A. have an overflow
B. be maintained in a sanitary manner
C. have hot and cold water
D. be equipped with a water-seal trap
Correct Answer: D
Rationale: Be equipped with a water-seal trap. Be trapped by an approved type water-
seal trap.
QUESTION 6
According to the Code, drainage systems were tested for tightness and for inspection shall be
tested with no less than a _______ head of water.
A. 6-foot
B. 8-foot
C. 10-foot
D. 12-foot
Correct Answer: C
Rationale: No section shall be tested with less than a 10-foot head of water.
,QUESTION 7
According to the Code, when notching the ends of joints to install water piping, the depth of
the notches shall not exceed _______ of the depth of the joints.
A. 1/16
B. 1/32
C. 1/8
D. 1/4
Correct Answer: D
Rationale: When notching the ends of joints, the depth shall not exceed 1/4 the depth of
the joints.
QUESTION 8
The Code requires that drainage fittings have threads that are tapped to allow for:
A. full thread engagement
B. grade
C. simple adjustment
D. pipe expansion
Correct Answer: B
Rationale: The threads of drainage fittings shall be tapped so as to allow for grade.
QUESTION 9
The Code requires that when a water service pipe is installed in the same trench with a building
sewer, there must be a minimum separation of _______ inches.
A. 6
B. 10
C. 12
D. 18
Correct Answer: C
Rationale: The bottom of the water service pipe, at all points, shall be at least 12 inches
above the top of the sewer pipe.
QUESTION 10
The Code requires that sewage or other waste from a plumbing system be _______ before it is
discharged into any waterway.
A. discharged through a settling tank
B. treated with Clorox
C. rendered innocuous
D. determined detrimental
Correct Answer: C
Rationale: Sewage or other waste must first be rendered innocuous.
, QUESTION 11
According to the Plumbing Code, _______ fixture unit(s) flow rate shall be deemed to be 1
cubic foot per minute.
A. 1
B. 2
C. 3
D. 4
Correct Answer: A
Rationale: A fixture unit flow rate shall be deemed to be 1 cubic foot of water per minute.
One fixture unit discharge capacity shall be deemed to be 7½ gallons per minute.
QUESTION 12
According to the Code, 2-inch copper tubing installed horizontally must be supported at
distances of not less than _______ feet.
A. 4
B. 6
C. 8
D. 10
Correct Answer: D
Rationale: Copper tubing shall be supported at approximately 10-foot intervals for
piping 2 inches and larger.
QUESTION 13
A single-family house, connected to a public sewer, may discharge all but one of the following
substances through its drainage system without violating the Code:
A. human excrement
B. potable water
C. fireplace ashes
D. clothes washer water
Correct Answer: C
Rationale: No substance which will clog the pipes shall be allowed to enter the building
drainage system. It shall be unlawful for any person to deposit, into any plumbing fixture
which is connected to any public sewer, any ashes.
