UA STAR Plumbing Mastery Certification
Exam Questions and Correct Answers
Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Remove waste solids
C. Allow air into the drainage system
D. Heat the piping
Answer: C
Rationale: Vent systems equalize pressure and allow proper drainage
flow by introducing air.
2. What is the minimum slope for a 3-inch horizontal drainage pipe?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
,D. 1/2 inch per foot
Answer: B
Rationale: Larger pipes (3" and above) typically require a minimum
slope of 1/8 inch per foot.
3. Which material is commonly used for potable water supply lines?
A. PVC
B. Cast iron
C. PEX
D. ABS
Answer: C
Rationale: PEX is widely used due to flexibility and resistance to
corrosion.
4. What does DWV stand for?
A. Drain Waste Vent
B. Direct Water Valve
C. Drain Water Volume
D. Dual Waste Vent
Answer: A
Rationale: DWV systems handle drainage, waste removal, and venting.
,5. What type of valve is used to prevent backflow?
A. Gate valve
B. Check valve
C. Ball valve
D. Globe valve
Answer: B
Rationale: Check valves allow flow in one direction only, preventing
backflow.
6. What is the function of a trap?
A. Increase pressure
B. Store water
C. Prevent sewer gases from entering buildings
D. Filter debris
Answer: C
Rationale: Traps retain water to block sewer gases.
7. Which pipe is best for underground drainage?
A. Copper
B. PVC
, C. Galvanized steel
D. Brass
Answer: B
Rationale: PVC is durable, corrosion-resistant, and commonly used
underground.
8. What is the maximum distance a trap arm can run before venting
(typical code)?
A. 2 feet
B. 4 feet
C. 6 feet
D. Depends on pipe size
Answer: D
Rationale: Trap arm length varies based on pipe diameter per code.
9. What fitting is used to change pipe direction by 45 degrees?
A. Tee
B. Wye
C. Elbow
D. Coupling
Exam Questions and Correct Answers
Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Remove waste solids
C. Allow air into the drainage system
D. Heat the piping
Answer: C
Rationale: Vent systems equalize pressure and allow proper drainage
flow by introducing air.
2. What is the minimum slope for a 3-inch horizontal drainage pipe?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
,D. 1/2 inch per foot
Answer: B
Rationale: Larger pipes (3" and above) typically require a minimum
slope of 1/8 inch per foot.
3. Which material is commonly used for potable water supply lines?
A. PVC
B. Cast iron
C. PEX
D. ABS
Answer: C
Rationale: PEX is widely used due to flexibility and resistance to
corrosion.
4. What does DWV stand for?
A. Drain Waste Vent
B. Direct Water Valve
C. Drain Water Volume
D. Dual Waste Vent
Answer: A
Rationale: DWV systems handle drainage, waste removal, and venting.
,5. What type of valve is used to prevent backflow?
A. Gate valve
B. Check valve
C. Ball valve
D. Globe valve
Answer: B
Rationale: Check valves allow flow in one direction only, preventing
backflow.
6. What is the function of a trap?
A. Increase pressure
B. Store water
C. Prevent sewer gases from entering buildings
D. Filter debris
Answer: C
Rationale: Traps retain water to block sewer gases.
7. Which pipe is best for underground drainage?
A. Copper
B. PVC
, C. Galvanized steel
D. Brass
Answer: B
Rationale: PVC is durable, corrosion-resistant, and commonly used
underground.
8. What is the maximum distance a trap arm can run before venting
(typical code)?
A. 2 feet
B. 4 feet
C. 6 feet
D. Depends on pipe size
Answer: D
Rationale: Trap arm length varies based on pipe diameter per code.
9. What fitting is used to change pipe direction by 45 degrees?
A. Tee
B. Wye
C. Elbow
D. Coupling
