NYC Master Plumber License Exam Questions
With Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following is the minimum slope for a horizontal
drainage pipe 3 inches in diameter?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Correct slope ensures proper drainage and prevents standing
water in the pipe.
2. A vent pipe is required to extend at least how far above the roof
surface?
A. 2 inches
B. 6 inches
C. 12 inches
D. 24 inches
This prevents the vent from being blocked by snow, debris, or
rainwater.
3. The main purpose of a trap in plumbing is to:
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Filter debris
D. Measure water flow
A trap holds water to create a seal against sewer gases.
,4. What is the minimum water supply pipe size for a single-family
dwelling?
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 1 1/4 inch
This size ensures adequate flow for household fixtures.
5. When installing a water closet, the rough-in measurement is the
distance from the finished wall to:
A. The center of the trapway
B. The center of the closet flange
C. The top of the bowl
D. The end of the water supply line
Accurate rough-in placement is critical for proper installation.
6. Lead solder is prohibited in potable water systems because:
A. It corrodes easily
B. It is too expensive
C. It is toxic
D. It weakens the pipe
Lead exposure can cause serious health issues; lead-free solder is
required.
7. The standard size of a residential water meter in NYC is:
A. 3/4 inch
B. 1 inch
C. 5/8 inch
D. 1 1/4 inch
, 5/8 inch meters meet typical household water demand
requirements.
8. Which type of pipe is most commonly used for natural gas in NYC?
A. PVC
B. CPVC
C. Black steel
D. Copper
Black steel provides strength and safety for gas distribution.
9. The purpose of a pressure-reducing valve is to:
A. Increase water flow
B. Heat the water
C. Reduce high incoming water pressure
D. Filter impurities
Protects plumbing fixtures from damage due to high pressure.
10. How often must backflow prevention devices be tested in
NYC?
A. Every 6 months
B. Every 1 year
C. Annually
D. Every 5 years
Regular testing ensures the device prevents contamination
effectively.
11. The maximum distance a water closet can be from a vent
pipe is:
A. 3 feet
B. 5 feet
C. 8 feet
With Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. Which of the following is the minimum slope for a horizontal
drainage pipe 3 inches in diameter?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Correct slope ensures proper drainage and prevents standing
water in the pipe.
2. A vent pipe is required to extend at least how far above the roof
surface?
A. 2 inches
B. 6 inches
C. 12 inches
D. 24 inches
This prevents the vent from being blocked by snow, debris, or
rainwater.
3. The main purpose of a trap in plumbing is to:
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Filter debris
D. Measure water flow
A trap holds water to create a seal against sewer gases.
,4. What is the minimum water supply pipe size for a single-family
dwelling?
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 1 1/4 inch
This size ensures adequate flow for household fixtures.
5. When installing a water closet, the rough-in measurement is the
distance from the finished wall to:
A. The center of the trapway
B. The center of the closet flange
C. The top of the bowl
D. The end of the water supply line
Accurate rough-in placement is critical for proper installation.
6. Lead solder is prohibited in potable water systems because:
A. It corrodes easily
B. It is too expensive
C. It is toxic
D. It weakens the pipe
Lead exposure can cause serious health issues; lead-free solder is
required.
7. The standard size of a residential water meter in NYC is:
A. 3/4 inch
B. 1 inch
C. 5/8 inch
D. 1 1/4 inch
, 5/8 inch meters meet typical household water demand
requirements.
8. Which type of pipe is most commonly used for natural gas in NYC?
A. PVC
B. CPVC
C. Black steel
D. Copper
Black steel provides strength and safety for gas distribution.
9. The purpose of a pressure-reducing valve is to:
A. Increase water flow
B. Heat the water
C. Reduce high incoming water pressure
D. Filter impurities
Protects plumbing fixtures from damage due to high pressure.
10. How often must backflow prevention devices be tested in
NYC?
A. Every 6 months
B. Every 1 year
C. Annually
D. Every 5 years
Regular testing ensures the device prevents contamination
effectively.
11. The maximum distance a water closet can be from a vent
pipe is:
A. 3 feet
B. 5 feet
C. 8 feet
