Ohio Journeyman Plumber Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. The minimum size water service pipe allowed for a single-family
dwelling is:
A. ½ inch
B. ¾ inch
C. 1 inch
D. 1 ¼ inch
¾ inch
Rationale: Most plumbing codes, including Ohio, set ¾ inch as the
minimum water service size for adequate flow and pressure.
2. A plumbing vent must terminate how far above the roof?
A. 4 inches
B. 6 inches
, C. 8 inches
D. 6 inches minimum
6 inches minimum
Rationale: Vents must extend at least 6 inches above the roof surface
to prevent blockages from snow and debris.
3. The minimum slope for horizontal drainage piping smaller than 4
inches 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
1/4 inch per foot
Rationale: Codes require ¼ inch per foot slope for pipes less than 4
inches to maintain proper flow and prevent clogging.
4. The maximum vertical distance between a trap and its vent is:
A. 2 feet
B. 4 feet
C. 6 feet
D. 10 feet
6 feet
Rationale: Code limits trap-to-vent distance to 6 feet for typical
fixture drains to avoid siphoning.
,5. A cleanout must be installed at every change of direction greater than:
A. 30 degrees
B. 45 degrees
C. 90 degrees
D. 180 degrees
90 degrees
Rationale: Cleanouts are required at changes of direction of 90
degrees or more to allow rodding access.
6. The minimum size trap for a bathtub is:
A. 1 ¼ inch
B. 1 ½ inch
C. 2 inches
D. 2 ½ inches
1 ½ inch
Rationale: Bathtubs require 1½ inch traps for sufficient drainage.
7. The minimum size vent for a water closet is:
A. 1 ¼ inch
B. 1 ½ inch
C. 2 inches
D. 3 inches
2 inches
Rationale: Toilets require a 2-inch minimum vent size per code.
, 8. A plumbing vent cannot terminate within how many feet horizontally
of a building air intake?
A. 6 feet
B. 10 feet
C. 12 feet
D. 15 feet
10 feet
Rationale: Vents must be at least 10 feet away horizontally from air
intakes to prevent odors from entering buildings.
9. The minimum depth of a building sewer below grade is:
A. 12 inches
B. 18 inches
C. 24 inches
D. 30 inches
12 inches
Rationale: Sewers must be buried at least 12 inches to provide frost
and mechanical protection.
10. What is the maximum spacing of supports for horizontal copper
tubing (½ inch)?
A. 4 feet
B. 6 feet
C. 8 feet
D. 10 feet
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. The minimum size water service pipe allowed for a single-family
dwelling is:
A. ½ inch
B. ¾ inch
C. 1 inch
D. 1 ¼ inch
¾ inch
Rationale: Most plumbing codes, including Ohio, set ¾ inch as the
minimum water service size for adequate flow and pressure.
2. A plumbing vent must terminate how far above the roof?
A. 4 inches
B. 6 inches
, C. 8 inches
D. 6 inches minimum
6 inches minimum
Rationale: Vents must extend at least 6 inches above the roof surface
to prevent blockages from snow and debris.
3. The minimum slope for horizontal drainage piping smaller than 4
inches 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
1/4 inch per foot
Rationale: Codes require ¼ inch per foot slope for pipes less than 4
inches to maintain proper flow and prevent clogging.
4. The maximum vertical distance between a trap and its vent is:
A. 2 feet
B. 4 feet
C. 6 feet
D. 10 feet
6 feet
Rationale: Code limits trap-to-vent distance to 6 feet for typical
fixture drains to avoid siphoning.
,5. A cleanout must be installed at every change of direction greater than:
A. 30 degrees
B. 45 degrees
C. 90 degrees
D. 180 degrees
90 degrees
Rationale: Cleanouts are required at changes of direction of 90
degrees or more to allow rodding access.
6. The minimum size trap for a bathtub is:
A. 1 ¼ inch
B. 1 ½ inch
C. 2 inches
D. 2 ½ inches
1 ½ inch
Rationale: Bathtubs require 1½ inch traps for sufficient drainage.
7. The minimum size vent for a water closet is:
A. 1 ¼ inch
B. 1 ½ inch
C. 2 inches
D. 3 inches
2 inches
Rationale: Toilets require a 2-inch minimum vent size per code.
, 8. A plumbing vent cannot terminate within how many feet horizontally
of a building air intake?
A. 6 feet
B. 10 feet
C. 12 feet
D. 15 feet
10 feet
Rationale: Vents must be at least 10 feet away horizontally from air
intakes to prevent odors from entering buildings.
9. The minimum depth of a building sewer below grade is:
A. 12 inches
B. 18 inches
C. 24 inches
D. 30 inches
12 inches
Rationale: Sewers must be buried at least 12 inches to provide frost
and mechanical protection.
10. What is the maximum spacing of supports for horizontal copper
tubing (½ inch)?
A. 4 feet
B. 6 feet
C. 8 feet
D. 10 feet
