NYC Plumber (DCAS) Certification
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Rationales 2026 Q&A | Instant
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1. A plumber is installing a new water service line. What is the primary purpose of
a curb stop?
A. To regulate internal pressure
B. To shut off water supply from the main
C. To filter debris from water
D. To measure water usage
Answer: B ✓
The curb stop allows the utility or plumber to shut off water supply from the
main line to the building.
2. Which material is most commonly used for residential DWV (drain, waste, vent)
piping?
A. Galvanized steel
B. Copper
C. PVC
D. Brass
Answer: C ✓
,PVC is widely used due to its corrosion resistance, lightweight nature, and ease
of installation.
3. What is the minimum slope required for horizontal drainage piping under NYC
code?
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: C ✓
Proper drainage slope ensures adequate flow and prevents clogging; 1/4 inch
per foot is standard.
4. A backflow preventer is required to:
A. Increase pressure
B. Prevent contaminated water from reversing flow
C. Filter water
D. Reduce pipe noise
Answer: B ✓
Backflow devices protect potable water by preventing reverse contamination.
5. What type of pipe is best suited for high-temperature water supply?
A. CPVC
B. PEX
C. PVC
D. ABS
Answer: A ✓
CPVC is designed for higher temperature tolerance compared to standard PVC.
, 6. A plumbing vent system primarily serves to:
A. Remove solids
B. Increase water pressure
C. Equalize pressure in drainage system
D. Heat water
Answer: C ✓
Vents allow air circulation, preventing vacuum and ensuring proper drainage.
7. What is the purpose of a trap seal?
A. Prevent leaks
B. Prevent sewer gases from entering the building
C. Improve flow
D. Filter solids
Answer: B ✓
The trap seal holds water that blocks sewer gases from entering occupied
spaces.
8. Which fitting is used to change pipe direction by 90 degrees?
A. Tee
B. Wye
C. Elbow
D. Coupling
Answer: C ✓
An elbow fitting is specifically designed for directional changes.
9. A pressure reducing valve (PRV) is installed to:
A. Increase pressure
B. Maintain safe water pressure levels
C. Filter water
D. Stop flow
Practice Exam Questions With Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf A+ Grade Guarantee
Verified By Professionals
1. A plumber is installing a new water service line. What is the primary purpose of
a curb stop?
A. To regulate internal pressure
B. To shut off water supply from the main
C. To filter debris from water
D. To measure water usage
Answer: B ✓
The curb stop allows the utility or plumber to shut off water supply from the
main line to the building.
2. Which material is most commonly used for residential DWV (drain, waste, vent)
piping?
A. Galvanized steel
B. Copper
C. PVC
D. Brass
Answer: C ✓
,PVC is widely used due to its corrosion resistance, lightweight nature, and ease
of installation.
3. What is the minimum slope required for horizontal drainage piping under NYC
code?
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: C ✓
Proper drainage slope ensures adequate flow and prevents clogging; 1/4 inch
per foot is standard.
4. A backflow preventer is required to:
A. Increase pressure
B. Prevent contaminated water from reversing flow
C. Filter water
D. Reduce pipe noise
Answer: B ✓
Backflow devices protect potable water by preventing reverse contamination.
5. What type of pipe is best suited for high-temperature water supply?
A. CPVC
B. PEX
C. PVC
D. ABS
Answer: A ✓
CPVC is designed for higher temperature tolerance compared to standard PVC.
, 6. A plumbing vent system primarily serves to:
A. Remove solids
B. Increase water pressure
C. Equalize pressure in drainage system
D. Heat water
Answer: C ✓
Vents allow air circulation, preventing vacuum and ensuring proper drainage.
7. What is the purpose of a trap seal?
A. Prevent leaks
B. Prevent sewer gases from entering the building
C. Improve flow
D. Filter solids
Answer: B ✓
The trap seal holds water that blocks sewer gases from entering occupied
spaces.
8. Which fitting is used to change pipe direction by 90 degrees?
A. Tee
B. Wye
C. Elbow
D. Coupling
Answer: C ✓
An elbow fitting is specifically designed for directional changes.
9. A pressure reducing valve (PRV) is installed to:
A. Increase pressure
B. Maintain safe water pressure levels
C. Filter water
D. Stop flow
