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Georgia Master Plumber Qualifying
Examination Advanced Practice Exam
2026 | 100 Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
1. A horizontal drainage pipe is 40 feet long and is installed at a slope of 1/4
inch per foot. What is the total required fall?
A. 5 inches
B. 8 inches
C. 10 inches
D. 12 inches
Answer: 10 inches
Rationale: Multiply the length by the slope: 40 ft × 1/4 in./ft = 10 inches of total
fall.
2. A 60-foot drainage run is installed at 1/8 inch per foot. What is the total
fall?
A. 5 inches
B. 7.5 inches
C. 10 inches
D. 12 inches
Answer: 7.5 inches
,Rationale: 60 × 1/8 = 7.5 inches.
3. A drainage pipe must fall 9 inches over 36 feet. What is the required slope?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 3/8 inch per foot
D. 1/2 inch per foot
Answer: 1/4 inch per foot
Rationale: Divide 9 inches by 36 feet: 9 ÷ 36 = 0.25 inch per foot.
4. A 4-inch horizontal building drain has 120 drainage fixture units connected
to it. What should the plumber do when sizing the pipe?
A. Automatically use a 2-inch pipe
B. Select the pipe size based on the applicable code capacity table and slope
C. Use the same size as the water service
D. Size it according to fixture water pressure
Answer: Select the pipe size based on the applicable code capacity table and
slope
Rationale: DWV sizing depends on drainage fixture units, pipe diameter, slope,
and the applicable code table rather than simply matching the water-service
size.
5. A branch drainage pipe serves fixtures totaling 18 DFU. Which information
is most important when determining its minimum size?
A. Building height only
B. DFU load, pipe slope, and applicable code table
C. Water-heater capacity
D. Gas pressure
Answer: DFU load, pipe slope, and applicable code table
,Rationale: Drainage sizing is determined from the calculated fixture load and
permitted pipe capacity at the proposed slope.
6. Four lavatories each contribute 1 DFU to a branch drain. What is the
combined load?
A. 1 DFU
B. 2 DFU
C. 4 DFU
D. 8 DFU
Answer: 4 DFU
Rationale: Fixture-unit loads are added for the drainage system: 1 + 1 + 1 + 1 = 4
DFU.
7. A commercial restroom contains six water closets, each assigned 4 DFU for
purposes of this practice problem. What is the combined water-closet
drainage load?
A. 10 DFU
B. 20 DFU
C. 24 DFU
D. 30 DFU
Answer: 24 DFU
Rationale: Six fixtures × 4 DFU each = 24 DFU. The actual fixture-unit values
must be taken from the applicable Georgia-adopted code table.
8. A building drain has 75 DFU of calculated load. Which approach is correct?
A. Select pipe size from the water-supply fixture-unit table
B. Select pipe size from the applicable drainage-capacity table based on slope
C. Use the largest available pipe
D. Use a pipe one size smaller than the building sewer
, Answer: Select pipe size from the applicable drainage-capacity table based on
slope
Rationale: DWV capacity tables establish allowable drainage loads for pipe sizes
and slopes.
9. Why should a drainage pipe not normally be oversized simply because a
larger pipe is available?
A. Larger pipe always increases pressure
B. Excessive diameter can reduce the velocity needed for effective transport of
solids
C. Larger pipe eliminates venting
D. Larger pipe prevents cleaning
Answer: Excessive diameter can reduce the velocity needed for effective
transport of solids
Rationale: Proper drainage design balances capacity and flow characteristics.
Oversizing can reduce flow velocity and contribute to sediment accumulation
under some conditions.
10.A 3-inch drain drops 12 inches over 48 feet. What is the slope?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: 1/4 inch per foot
Rationale: 12 inches ÷ 48 feet = 0.25 inch per foot.
11.What is the primary reason horizontal drainage piping must be installed
with the prescribed minimum slope?
A. To create positive water pressure
B. To provide gravity flow and appropriate drainage performance
Georgia Master Plumber Qualifying
Examination Advanced Practice Exam
2026 | 100 Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
1. A horizontal drainage pipe is 40 feet long and is installed at a slope of 1/4
inch per foot. What is the total required fall?
A. 5 inches
B. 8 inches
C. 10 inches
D. 12 inches
Answer: 10 inches
Rationale: Multiply the length by the slope: 40 ft × 1/4 in./ft = 10 inches of total
fall.
2. A 60-foot drainage run is installed at 1/8 inch per foot. What is the total
fall?
A. 5 inches
B. 7.5 inches
C. 10 inches
D. 12 inches
Answer: 7.5 inches
,Rationale: 60 × 1/8 = 7.5 inches.
3. A drainage pipe must fall 9 inches over 36 feet. What is the required slope?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 3/8 inch per foot
D. 1/2 inch per foot
Answer: 1/4 inch per foot
Rationale: Divide 9 inches by 36 feet: 9 ÷ 36 = 0.25 inch per foot.
4. A 4-inch horizontal building drain has 120 drainage fixture units connected
to it. What should the plumber do when sizing the pipe?
A. Automatically use a 2-inch pipe
B. Select the pipe size based on the applicable code capacity table and slope
C. Use the same size as the water service
D. Size it according to fixture water pressure
Answer: Select the pipe size based on the applicable code capacity table and
slope
Rationale: DWV sizing depends on drainage fixture units, pipe diameter, slope,
and the applicable code table rather than simply matching the water-service
size.
5. A branch drainage pipe serves fixtures totaling 18 DFU. Which information
is most important when determining its minimum size?
A. Building height only
B. DFU load, pipe slope, and applicable code table
C. Water-heater capacity
D. Gas pressure
Answer: DFU load, pipe slope, and applicable code table
,Rationale: Drainage sizing is determined from the calculated fixture load and
permitted pipe capacity at the proposed slope.
6. Four lavatories each contribute 1 DFU to a branch drain. What is the
combined load?
A. 1 DFU
B. 2 DFU
C. 4 DFU
D. 8 DFU
Answer: 4 DFU
Rationale: Fixture-unit loads are added for the drainage system: 1 + 1 + 1 + 1 = 4
DFU.
7. A commercial restroom contains six water closets, each assigned 4 DFU for
purposes of this practice problem. What is the combined water-closet
drainage load?
A. 10 DFU
B. 20 DFU
C. 24 DFU
D. 30 DFU
Answer: 24 DFU
Rationale: Six fixtures × 4 DFU each = 24 DFU. The actual fixture-unit values
must be taken from the applicable Georgia-adopted code table.
8. A building drain has 75 DFU of calculated load. Which approach is correct?
A. Select pipe size from the water-supply fixture-unit table
B. Select pipe size from the applicable drainage-capacity table based on slope
C. Use the largest available pipe
D. Use a pipe one size smaller than the building sewer
, Answer: Select pipe size from the applicable drainage-capacity table based on
slope
Rationale: DWV capacity tables establish allowable drainage loads for pipe sizes
and slopes.
9. Why should a drainage pipe not normally be oversized simply because a
larger pipe is available?
A. Larger pipe always increases pressure
B. Excessive diameter can reduce the velocity needed for effective transport of
solids
C. Larger pipe eliminates venting
D. Larger pipe prevents cleaning
Answer: Excessive diameter can reduce the velocity needed for effective
transport of solids
Rationale: Proper drainage design balances capacity and flow characteristics.
Oversizing can reduce flow velocity and contribute to sediment accumulation
under some conditions.
10.A 3-inch drain drops 12 inches over 48 feet. What is the slope?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: 1/4 inch per foot
Rationale: 12 inches ÷ 48 feet = 0.25 inch per foot.
11.What is the primary reason horizontal drainage piping must be installed
with the prescribed minimum slope?
A. To create positive water pressure
B. To provide gravity flow and appropriate drainage performance
