Georgia Plumbing Contractor License Exam 2026 – 195 Practice
Questions with Answers & Detailed Rationales, Georgia Plumbing
Code, DWV Systems, Water Supply, Venting, Gas Code, Backflow
Prevention, Licensing Law, Plan Reading & Safety
Section 1: Drainage, Waste, and Vent Systems (Questions 1–40)
Question 1
A horizontal drainage pipe must carry a calculated load of 42 drainage fixture units (DFU)
over a distance of 65 feet at a slope of 1/8 inch per foot. What is the most critical factor in
selecting the pipe diameter?
A. The water supply fixture unit count
B. The applicable Georgia-adopted drainage capacity table based on slope and DFU
C. The building height and number of stories
D. The diameter of the building sewer
Correct Answer: B
Explanation: Drainage sizing depends on DFU load, slope, and the code capacity table; water
supply and building height are not sizing factors for DWV.
Question 2
A plumber is installing a 4-inch horizontal building drain that receives discharge from six
water closets (4 DFU each) and twelve lavatories (1 DFU each). What is the total calculated
drainage load in fixture units?
A. 24 DFU
,B. 36 DFU
C. 48 DFU
D. 60 DFU
Correct Answer: B
Explanation: Six water closets at 4 DFU each equals 24 DFU; twelve lavatories at 1 DFU each
equals 12 DFU; total is 36 DFU.
Question 3
Why does the Georgia Plumbing Code limit the maximum slope of horizontal drainage piping
serving water closets?
A. To prevent excessive velocity that could cause solids to be left behind
B. To reduce the required pipe diameter
C. To prevent trap siphonage in adjacent fixtures
D. To minimize the number of cleanouts required
Correct Answer: A
Explanation: Excessive slope can cause water to drain faster than solids, leaving waste
behind; codes limit slope to ensure self-scouring flow.
Question 4
A 3-inch horizontal drainage pipe is installed at a slope of 1/4 inch per foot. What is the total
fall over a 48-foot run?
,A. 8 inches
B. 10 inches
C. 12 inches
D. 14 inches
Correct Answer: C
Explanation: 48 feet multiplied by 1/4 inch per foot equals 12 inches of total fall; always
verify slope against code tables.
Question 5
What fitting is required at the base of a vertical drainage stack where it transitions to a
horizontal building drain?
A. Sanitary tee
B. Long-turn quarter bend
C. Combination wye and 1/8 bend
D. Straight coupling
Correct Answer: C
Explanation: A combination wye and 1/8 bend provides a smooth transition from vertical to
horizontal flow, reducing turbulence and blockages.
Question 6
A cleanout is required at the base of every vertical stack and at intervals not exceeding what
distance in horizontal drainage piping?
, A. 50 feet
B. 75 feet
C. 100 feet
D. 125 feet
Correct Answer: C
Explanation: Georgia code requires cleanouts at intervals not exceeding 100 feet in
horizontal drainage piping to allow proper maintenance access.
Question 7
In a 10-story building, a 4-inch soil stack receives discharge from fixtures on all floors. What
is the primary purpose of installing a relief vent at the base of the stack?
A. To increase drainage velocity
B. To provide pressure equalization and prevent trap siphonage
C. To reduce pipe diameter requirements
D. To serve as a cleanout access point
Correct Answer: B
Explanation: Relief vents equalize pressure at the base of tall stacks, protecting trap seals
from siphonage during heavy flow conditions.
Question 8
Questions with Answers & Detailed Rationales, Georgia Plumbing
Code, DWV Systems, Water Supply, Venting, Gas Code, Backflow
Prevention, Licensing Law, Plan Reading & Safety
Section 1: Drainage, Waste, and Vent Systems (Questions 1–40)
Question 1
A horizontal drainage pipe must carry a calculated load of 42 drainage fixture units (DFU)
over a distance of 65 feet at a slope of 1/8 inch per foot. What is the most critical factor in
selecting the pipe diameter?
A. The water supply fixture unit count
B. The applicable Georgia-adopted drainage capacity table based on slope and DFU
C. The building height and number of stories
D. The diameter of the building sewer
Correct Answer: B
Explanation: Drainage sizing depends on DFU load, slope, and the code capacity table; water
supply and building height are not sizing factors for DWV.
Question 2
A plumber is installing a 4-inch horizontal building drain that receives discharge from six
water closets (4 DFU each) and twelve lavatories (1 DFU each). What is the total calculated
drainage load in fixture units?
A. 24 DFU
,B. 36 DFU
C. 48 DFU
D. 60 DFU
Correct Answer: B
Explanation: Six water closets at 4 DFU each equals 24 DFU; twelve lavatories at 1 DFU each
equals 12 DFU; total is 36 DFU.
Question 3
Why does the Georgia Plumbing Code limit the maximum slope of horizontal drainage piping
serving water closets?
A. To prevent excessive velocity that could cause solids to be left behind
B. To reduce the required pipe diameter
C. To prevent trap siphonage in adjacent fixtures
D. To minimize the number of cleanouts required
Correct Answer: A
Explanation: Excessive slope can cause water to drain faster than solids, leaving waste
behind; codes limit slope to ensure self-scouring flow.
Question 4
A 3-inch horizontal drainage pipe is installed at a slope of 1/4 inch per foot. What is the total
fall over a 48-foot run?
,A. 8 inches
B. 10 inches
C. 12 inches
D. 14 inches
Correct Answer: C
Explanation: 48 feet multiplied by 1/4 inch per foot equals 12 inches of total fall; always
verify slope against code tables.
Question 5
What fitting is required at the base of a vertical drainage stack where it transitions to a
horizontal building drain?
A. Sanitary tee
B. Long-turn quarter bend
C. Combination wye and 1/8 bend
D. Straight coupling
Correct Answer: C
Explanation: A combination wye and 1/8 bend provides a smooth transition from vertical to
horizontal flow, reducing turbulence and blockages.
Question 6
A cleanout is required at the base of every vertical stack and at intervals not exceeding what
distance in horizontal drainage piping?
, A. 50 feet
B. 75 feet
C. 100 feet
D. 125 feet
Correct Answer: C
Explanation: Georgia code requires cleanouts at intervals not exceeding 100 feet in
horizontal drainage piping to allow proper maintenance access.
Question 7
In a 10-story building, a 4-inch soil stack receives discharge from fixtures on all floors. What
is the primary purpose of installing a relief vent at the base of the stack?
A. To increase drainage velocity
B. To provide pressure equalization and prevent trap siphonage
C. To reduce pipe diameter requirements
D. To serve as a cleanout access point
Correct Answer: B
Explanation: Relief vents equalize pressure at the base of tall stacks, protecting trap seals
from siphonage during heavy flow conditions.
Question 8
