Nevada Plumbing Inspector
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
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1. Which type of pipe is most commonly used for potable water
distribution in residential plumbing?
A. Cast iron
B. Copper
C. PEX
D. Galvanized steel
PEX is widely used due to its flexibility, corrosion resistance, and ease
of installation in residential water supply systems.
2. What is the minimum slope required for a 2-inch horizontal drain pipe
to ensure proper gravity drainage?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
The 1/4 inch per foot slope allows wastewater to flow properly
without causing blockages or standing water in a 2-inch drain pipe.
3. Which of the following is an acceptable method to join ABS plastic
pipes?
A. Solvent cement
B. Threaded fittings
C. Solder
D. Solvent cement
ABS pipes are joined using solvent cement, which chemically fuses
the pipe and fitting to create a watertight seal.
,4. What is the primary purpose of a trap in plumbing?
A. To reduce water pressure
B. To prevent sewer gases from entering the building
C. To increase flow rate
D. To prevent sewer gases from entering the building
Traps hold a water seal that blocks the passage of sewer gases while
allowing wastewater to flow freely.
5. Which fixture requires an air gap to prevent backflow contamination?
A. Toilet
B. Laundry tub
C. Dishwasher
D. Shower
Air gaps prevent backflow from contaminating potable water;
dishwashers often require them due to potential cross-connection
with sinks.
6. What is the maximum allowable distance from a trap to a vent in a
1.5-inch drain line?
A. 3 feet
B. 4 feet
C. 5 feet
D. 6 feet
For a 1.5-inch line, plumbing codes allow up to 5 feet between the
trap and vent to maintain proper venting and prevent siphoning.
7. Which valve type is recommended for water shutoff in residential
plumbing due to reliability and ease of maintenance?
A. Gate valve
B. Ball valve
C. Ball valve
D. Globe valve
Ball valves provide a reliable, full shutoff with minimal pressure loss
and are less prone to wear compared to gate or globe valves.
8. What is the minimum clearance required between a water closet and
side walls or partitions?
A. 12 inches
B. 15 inches
, C. 18 inches
D. 24 inches
Code requires at least 15 inches from the centerline of a toilet to
adjacent walls or partitions to allow safe and comfortable use.
9. Which material is prohibited for potable water piping in Nevada due to
lead content?
A. CPVC
B. Copper
C. Galvanized leaded pipe
D. PEX
Galvanized pipes with lead content are banned for drinking water
due to the risk of lead contamination.
10. A plumbing inspector notices a water heater temperature set
above 140°F. What is the main concern?
A. Low water pressure
B. Energy waste
C. Scalding hazard
D. Corrosion
Temperatures above 140°F can cause serious scalding injuries,
particularly to children and the elderly.
11. What is the proper venting method for a standpipe used for a
clothes washer?
A. Indirect vent
B. Direct vent to a stack
C. Loop vent
D. Air admittance valve only
Clothes washer standpipes must be vented directly to the drainage
system or stack to prevent siphoning and ensure proper drainage.
12. Which of the following is considered a cross-connection in
plumbing systems?
A. Two hot water lines connected
B. Potable water line connected to irrigation system
C. Cold water feed split to two fixtures
D. Vent connected to drain line
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which type of pipe is most commonly used for potable water
distribution in residential plumbing?
A. Cast iron
B. Copper
C. PEX
D. Galvanized steel
PEX is widely used due to its flexibility, corrosion resistance, and ease
of installation in residential water supply systems.
2. What is the minimum slope required for a 2-inch horizontal drain pipe
to ensure proper gravity drainage?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
The 1/4 inch per foot slope allows wastewater to flow properly
without causing blockages or standing water in a 2-inch drain pipe.
3. Which of the following is an acceptable method to join ABS plastic
pipes?
A. Solvent cement
B. Threaded fittings
C. Solder
D. Solvent cement
ABS pipes are joined using solvent cement, which chemically fuses
the pipe and fitting to create a watertight seal.
,4. What is the primary purpose of a trap in plumbing?
A. To reduce water pressure
B. To prevent sewer gases from entering the building
C. To increase flow rate
D. To prevent sewer gases from entering the building
Traps hold a water seal that blocks the passage of sewer gases while
allowing wastewater to flow freely.
5. Which fixture requires an air gap to prevent backflow contamination?
A. Toilet
B. Laundry tub
C. Dishwasher
D. Shower
Air gaps prevent backflow from contaminating potable water;
dishwashers often require them due to potential cross-connection
with sinks.
6. What is the maximum allowable distance from a trap to a vent in a
1.5-inch drain line?
A. 3 feet
B. 4 feet
C. 5 feet
D. 6 feet
For a 1.5-inch line, plumbing codes allow up to 5 feet between the
trap and vent to maintain proper venting and prevent siphoning.
7. Which valve type is recommended for water shutoff in residential
plumbing due to reliability and ease of maintenance?
A. Gate valve
B. Ball valve
C. Ball valve
D. Globe valve
Ball valves provide a reliable, full shutoff with minimal pressure loss
and are less prone to wear compared to gate or globe valves.
8. What is the minimum clearance required between a water closet and
side walls or partitions?
A. 12 inches
B. 15 inches
, C. 18 inches
D. 24 inches
Code requires at least 15 inches from the centerline of a toilet to
adjacent walls or partitions to allow safe and comfortable use.
9. Which material is prohibited for potable water piping in Nevada due to
lead content?
A. CPVC
B. Copper
C. Galvanized leaded pipe
D. PEX
Galvanized pipes with lead content are banned for drinking water
due to the risk of lead contamination.
10. A plumbing inspector notices a water heater temperature set
above 140°F. What is the main concern?
A. Low water pressure
B. Energy waste
C. Scalding hazard
D. Corrosion
Temperatures above 140°F can cause serious scalding injuries,
particularly to children and the elderly.
11. What is the proper venting method for a standpipe used for a
clothes washer?
A. Indirect vent
B. Direct vent to a stack
C. Loop vent
D. Air admittance valve only
Clothes washer standpipes must be vented directly to the drainage
system or stack to prevent siphoning and ensure proper drainage.
12. Which of the following is considered a cross-connection in
plumbing systems?
A. Two hot water lines connected
B. Potable water line connected to irrigation system
C. Cold water feed split to two fixtures
D. Vent connected to drain line
