Georgia Master Plumber Class I
Examination Restricted Practice Exam
2026 | 100 Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Prevent sewer gases from entering occupied spaces
C. Reduce pipe diameter
D. Increase drainage flow
Answer: Prevent sewer gases from entering occupied spaces
Rationale: Venting protects trap seals and allows the drainage system to
operate properly by balancing air pressure and preventing sewer gases from
entering the building.
2. Which plumbing system carries wastewater away from fixtures?
A. Water supply system
B. Drainage system
C. Fuel-gas system
D. Hydronic system
,Answer: Drainage system
Rationale: The drainage system conveys wastewater and sewage from plumbing
fixtures to an approved disposal or sewer system.
3. What is the primary function of a plumbing trap?
A. Increase water pressure
B. Prevent backflow from the water main
C. Maintain a water seal against sewer gases
D. Filter potable water
Answer: Maintain a water seal against sewer gases
Rationale: A trap retains water that forms a seal between the fixture and the
drainage system, helping prevent sewer gases from entering the building.
4. Which fitting is generally used to change the direction of a drainage pipe by
90 degrees?
A. Coupling
B. Elbow
C. Union
D. Reducer
Answer: Elbow
Rationale: Elbows are designed to change the direction of piping. Drainage
systems commonly use fittings designed for smooth flow, such as drainage-
pattern elbows.
5. What is the purpose of a cleanout?
A. Increase water pressure
B. Provide access for cleaning drainage piping
C. Prevent freezing
D. Supply air to fixtures
,Answer: Provide access for cleaning drainage piping
Rationale: Cleanouts provide accessible openings through which drainage piping
can be inspected and cleared of obstructions.
6. Which material is commonly used for potable water distribution?
A. Cast iron soil pipe
B. Copper tubing
C. Clay sewer pipe
D. Concrete pipe
Answer: Copper tubing
Rationale: Copper tubing is widely used for potable water distribution because
of its durability, corrosion resistance, and suitability for drinking-water systems.
7. What does the term "DWV" stand for?
A. Drain, Water, Valve
B. Domestic Water Vent
C. Drain, Waste, and Vent
D. Drainage Water Volume
Answer: Drain, Waste, and Vent
Rationale: DWV describes the piping system used to convey wastewater and
provide ventilation for drainage piping.
8. What is the purpose of a pressure-reducing valve?
A. Increase supply pressure
B. Reduce excessive water pressure
C. Remove sediment
D. Prevent sewer gases
Answer: Reduce excessive water pressure
, Rationale: A pressure-reducing valve regulates excessive incoming water
pressure to a safer level for the building plumbing system.
9. What device is commonly used to prevent contaminated water from
flowing backward into a potable water supply?
A. Cleanout
B. Backflow preventer
C. Trap primer
D. Water hammer arrestor
Answer: Backflow preventer
Rationale: Backflow prevention devices protect potable water from
contamination caused by backpressure or backsiphonage.
10.What is backsiphonage?
A. Increased sewer pressure
B. Reverse flow caused by negative pressure in the water supply
C. Water leaking from a fixture
D. Air entering a drain
Answer: Reverse flow caused by negative pressure in the water supply
Rationale: Backsiphonage occurs when a reduction in supply pressure creates a
siphoning action that can draw contaminated water into the potable system.
11.What is the purpose of a water hammer arrestor?
A. Prevent sewer gases
B. Absorb shock caused by sudden changes in water velocity
C. Increase water temperature
D. Reduce pipe size
Answer: Absorb shock caused by sudden changes in water velocity
Examination Restricted Practice Exam
2026 | 100 Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Prevent sewer gases from entering occupied spaces
C. Reduce pipe diameter
D. Increase drainage flow
Answer: Prevent sewer gases from entering occupied spaces
Rationale: Venting protects trap seals and allows the drainage system to
operate properly by balancing air pressure and preventing sewer gases from
entering the building.
2. Which plumbing system carries wastewater away from fixtures?
A. Water supply system
B. Drainage system
C. Fuel-gas system
D. Hydronic system
,Answer: Drainage system
Rationale: The drainage system conveys wastewater and sewage from plumbing
fixtures to an approved disposal or sewer system.
3. What is the primary function of a plumbing trap?
A. Increase water pressure
B. Prevent backflow from the water main
C. Maintain a water seal against sewer gases
D. Filter potable water
Answer: Maintain a water seal against sewer gases
Rationale: A trap retains water that forms a seal between the fixture and the
drainage system, helping prevent sewer gases from entering the building.
4. Which fitting is generally used to change the direction of a drainage pipe by
90 degrees?
A. Coupling
B. Elbow
C. Union
D. Reducer
Answer: Elbow
Rationale: Elbows are designed to change the direction of piping. Drainage
systems commonly use fittings designed for smooth flow, such as drainage-
pattern elbows.
5. What is the purpose of a cleanout?
A. Increase water pressure
B. Provide access for cleaning drainage piping
C. Prevent freezing
D. Supply air to fixtures
,Answer: Provide access for cleaning drainage piping
Rationale: Cleanouts provide accessible openings through which drainage piping
can be inspected and cleared of obstructions.
6. Which material is commonly used for potable water distribution?
A. Cast iron soil pipe
B. Copper tubing
C. Clay sewer pipe
D. Concrete pipe
Answer: Copper tubing
Rationale: Copper tubing is widely used for potable water distribution because
of its durability, corrosion resistance, and suitability for drinking-water systems.
7. What does the term "DWV" stand for?
A. Drain, Water, Valve
B. Domestic Water Vent
C. Drain, Waste, and Vent
D. Drainage Water Volume
Answer: Drain, Waste, and Vent
Rationale: DWV describes the piping system used to convey wastewater and
provide ventilation for drainage piping.
8. What is the purpose of a pressure-reducing valve?
A. Increase supply pressure
B. Reduce excessive water pressure
C. Remove sediment
D. Prevent sewer gases
Answer: Reduce excessive water pressure
, Rationale: A pressure-reducing valve regulates excessive incoming water
pressure to a safer level for the building plumbing system.
9. What device is commonly used to prevent contaminated water from
flowing backward into a potable water supply?
A. Cleanout
B. Backflow preventer
C. Trap primer
D. Water hammer arrestor
Answer: Backflow preventer
Rationale: Backflow prevention devices protect potable water from
contamination caused by backpressure or backsiphonage.
10.What is backsiphonage?
A. Increased sewer pressure
B. Reverse flow caused by negative pressure in the water supply
C. Water leaking from a fixture
D. Air entering a drain
Answer: Reverse flow caused by negative pressure in the water supply
Rationale: Backsiphonage occurs when a reduction in supply pressure creates a
siphoning action that can draw contaminated water into the potable system.
11.What is the purpose of a water hammer arrestor?
A. Prevent sewer gases
B. Absorb shock caused by sudden changes in water velocity
C. Increase water temperature
D. Reduce pipe size
Answer: Absorb shock caused by sudden changes in water velocity
