1|Page
WI Journeyman Plumber2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS WILL
COME FROM HERE (100% CORRECT ANSWERS A+ GRADED
1. According to the Wisconsin Plumbing Code, what is the minimum
required diameter for a building sewer serving a single-family dwelling?
A) 3 inches
B) 4 inches
C) 5 inches
D) 6 inches
Answer: B) 4 inches
Explanation: The Wisconsin Uniform Plumbing Code requires a
minimum of a 4-inch building sewer for a single-family home to handle
the combined discharge of all plumbing fixtures, ensuring adequate
flow and venting.
2. When pressure testing a DWV system with water, what is the
standard head pressure the system must hold?
A) 5 feet
B) 10 feet
C) 15 feet
D) 25 feet
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Answer: B) 10 feet
Explanation: A 10-foot head of water (which equates to approximately
4.3 psi) is the standard test pressure for a DWV system to verify the
integrity of all joints without exceeding material limits.
3. What is the primary purpose of a trap primer?
A) To accelerate drainage flow
B) To prevent sewer gas from entering
C) To maintain the water seal in an infrequently used floor drain trap
D) To prime the main vent stack
Answer: C) To maintain the water seal in an infrequently used floor
drain trap
Explanation: A trap primer automatically replenishes water lost to
evaporation in a trap seal, ensuring a liquid barrier against sewer gases
is constantly maintained.
4. In a residential plumbing system, what is the maximum developed
length of a fixture trap arm for a 1-1/2 inch trap?
A) 3 feet 6 inches
B) 5 feet
C) 6 feet
D) 8 feet
Answer: C) 6 feet
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Explanation: Code limits the trap arm length based on the trap
diameter to prevent the loss of the water seal through siphoning. A 1-
1/2 inch trap has a maximum trap arm length of 6 feet before it must
be vented.
5. What type of copper tube is designated by a blue color stripe and is
primarily used for underground water services?
A) Type M
B) Type DWV
C) Type L
D) Type K
Answer: D) Type K
Explanation: Type K copper tubing has the thickest wall of the common
types, making it suitable for underground service where it must
withstand high external soil pressure and is identified by a blue stripe.
6. A branch interval in a drainage stack is defined as a vertical distance
of at least:
A) 4 feet
B) 8 feet
C) 10 feet
D) 16 feet
Answer: B) 8 feet
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Explanation: A branch interval is a vertical depth of at least 8 floors-
feet, or the story height, on a soil or waste stack corresponding to the
location of one or more horizontal branch connections.
7. What U.S. federal law aims to protect the quality of the public's
drinking water by regulating backflow prevention?
A) Clean Air Act
B) Safe Drinking Water Act
C) Resource Conservation and Recovery Act
D) Lead and Copper Rule
Answer: B) Clean Water Act
Explanation: The Safe Water Drinking Act (SDWA) is the foundational
federal law that empowers the EPA to set standards for drinking water
quality and requires states to implement programs to prevent
contamination, including backflow prevention.
8. A major concern with using flexible corrugated connectors on water
heaters is:
A) Excessive water pressure drop
B) Accelerated corrosion due to dissimilar metals
C) Reduced GPM flow rates due to turbulence and smaller internal
diameter
D) The potential for a catastrophic flood if the copper corrugations
work-harden and crack
WI Journeyman Plumber2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS WILL
COME FROM HERE (100% CORRECT ANSWERS A+ GRADED
1. According to the Wisconsin Plumbing Code, what is the minimum
required diameter for a building sewer serving a single-family dwelling?
A) 3 inches
B) 4 inches
C) 5 inches
D) 6 inches
Answer: B) 4 inches
Explanation: The Wisconsin Uniform Plumbing Code requires a
minimum of a 4-inch building sewer for a single-family home to handle
the combined discharge of all plumbing fixtures, ensuring adequate
flow and venting.
2. When pressure testing a DWV system with water, what is the
standard head pressure the system must hold?
A) 5 feet
B) 10 feet
C) 15 feet
D) 25 feet
,2|Page
Answer: B) 10 feet
Explanation: A 10-foot head of water (which equates to approximately
4.3 psi) is the standard test pressure for a DWV system to verify the
integrity of all joints without exceeding material limits.
3. What is the primary purpose of a trap primer?
A) To accelerate drainage flow
B) To prevent sewer gas from entering
C) To maintain the water seal in an infrequently used floor drain trap
D) To prime the main vent stack
Answer: C) To maintain the water seal in an infrequently used floor
drain trap
Explanation: A trap primer automatically replenishes water lost to
evaporation in a trap seal, ensuring a liquid barrier against sewer gases
is constantly maintained.
4. In a residential plumbing system, what is the maximum developed
length of a fixture trap arm for a 1-1/2 inch trap?
A) 3 feet 6 inches
B) 5 feet
C) 6 feet
D) 8 feet
Answer: C) 6 feet
,3|Page
Explanation: Code limits the trap arm length based on the trap
diameter to prevent the loss of the water seal through siphoning. A 1-
1/2 inch trap has a maximum trap arm length of 6 feet before it must
be vented.
5. What type of copper tube is designated by a blue color stripe and is
primarily used for underground water services?
A) Type M
B) Type DWV
C) Type L
D) Type K
Answer: D) Type K
Explanation: Type K copper tubing has the thickest wall of the common
types, making it suitable for underground service where it must
withstand high external soil pressure and is identified by a blue stripe.
6. A branch interval in a drainage stack is defined as a vertical distance
of at least:
A) 4 feet
B) 8 feet
C) 10 feet
D) 16 feet
Answer: B) 8 feet
, 4|Page
Explanation: A branch interval is a vertical depth of at least 8 floors-
feet, or the story height, on a soil or waste stack corresponding to the
location of one or more horizontal branch connections.
7. What U.S. federal law aims to protect the quality of the public's
drinking water by regulating backflow prevention?
A) Clean Air Act
B) Safe Drinking Water Act
C) Resource Conservation and Recovery Act
D) Lead and Copper Rule
Answer: B) Clean Water Act
Explanation: The Safe Water Drinking Act (SDWA) is the foundational
federal law that empowers the EPA to set standards for drinking water
quality and requires states to implement programs to prevent
contamination, including backflow prevention.
8. A major concern with using flexible corrugated connectors on water
heaters is:
A) Excessive water pressure drop
B) Accelerated corrosion due to dissimilar metals
C) Reduced GPM flow rates due to turbulence and smaller internal
diameter
D) The potential for a catastrophic flood if the copper corrugations
work-harden and crack
