Journeyman Plumber Licensing Exam

Journeyman Plumber Licensing Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

What is the minimum size of a trap arm for a water closet? 1.

• 2 inches
• 3 inches
• 4 inches
• 1½ inches

Rationale: Water closets require a minimum 3-inch trap arm to properly

handle waste discharge and prevent clogging.

The main purpose of a plumbing vent is to: 2.

• Provide water to fixtures
• Equalize air pressure in the drainage system
• Stop sewer gas leaks
• Increase water flow 1 / 4

Rationale: Vents prevent negative pressure that could siphon traps and

allow smooth waste flow.

What type of fitting is used to connect two pipes of different sizes in a 3.straight line?

• Elbow
• Reducer coupling
• Cross
• Wye

Rationale: A reducer coupling transitions between different pipe diameters

while maintaining alignment.

The minimum slope for a 3-inch horizontal drainage pipe is: 4.

• ¼ inch per foot
• ⅛ inch per foot
• ½ inch per foot
• 1 inch per foot

Rationale: ⅛ inch per foot is sufficient for 3-inch or larger pipes to maintain flow without excessive velocity.

A plumbing trap must: 5.

• Be vented on the outlet side only 2 / 4

• Hold at least 4 inches of water
• Seal against sewer gases
• Be installed vertically

Rationale: The trap’s water seal blocks sewer gases from entering living

spaces.

What type of valve is commonly used on gas lines? 6.

• Gate valve
• Globe valve
• Ball valve
• Check valve

Rationale: Ball valves allow quick shutoff and are suitable for gas line

safety.

A water heater’s temperature relief valve must discharge: 7.

• Into a vent stack
• Into a floor drain
• Onto the floor
• To an approved discharge location by gravity

Rationale: T&P valves must safely discharge by gravity to prevent scalding

or pressure buildup.

• / 4

Which of the following materials is approved for underground drainage 8.piping?

• Galvanized steel
• PVC (Schedule 40)
• Copper DWV
• Lead

Rationale: PVC Schedule 40 is corrosion-resistant and widely approved for

underground use.

The maximum trap seal depth allowed by code is typically: 9.

• ½ inch
• 1 inch
• 4 inches
• 6 inches

Rationale: Excessive trap seal depth can slow drainage and lead to

siphonage.

What is the minimum distance between a cleanout and the wall it faces? 10.

• 6 inches
• 12 inches
• 18 inches
• 24 inches
• / 4