USVI Journeyman Plumber Licensing Exam 2026 – 190
Comprehensive Practice Questions with Answers & Detailed
Rationales, 2024 Uniform Plumbing Code, Water Supply, Drainage
and Venting, Pipe Installation, Plumbing Fixtures, Safety Standards,
USVI Licensing Regulations & PSI Exam Preparation
SECTION 1: DRAINAGE SYSTEMS (Questions 1–25)
Question 1
A horizontal drainage pipe serving a residential lavatory must be installed with a minimum
slope. What is the primary engineering purpose of this slope requirement?
A. To increase the water pressure at the fixture outlet
B. To allow gravity to convey wastewater and solids while preventing deposition
C. To reduce the noise transmission through the drainage piping
D. To allow the vent system to function without a loop
Correct Answer: B
Explanation: Proper slope allows gravity to move wastewater and solids through piping while
minimizing blockage. Slope creates velocity sufficient to scour the pipe interior. Insufficient
slope causes solids to settle; excessive slope allows water to outrun solids.
Question 2
During a rough-in inspection of a commercial building, an inspector observes a horizontal
drainage branch installed at a slope of 1/8 inch per foot. The pipe diameter is 2 inches. What
is the most likely code compliance determination?
A. The installation is acceptable because 1/8 inch per foot is the standard minimum for all
diameters
,B. The installation is non-compliant because 2-inch pipe requires 1/4 inch per foot minimum
slope
C. The installation is acceptable because commercial occupancies allow reduced slope
D. The installation is non-compliant because all horizontal drainage requires 1/2 inch per
foot
Correct Answer: B
Explanation: Pipes 2½ inches and smaller require 1/4 inch per foot minimum slope. Pipes 3
inches and larger may use 1/8 inch per foot. Using inadequate slope on small-diameter pipes
causes chronic blockages.
Question 3
A plumbing contractor is installing a building drain that passes through the foundation wall.
The portion of piping outside the building that conveys drainage to the public sewer is
properly termed:
A. The building drain
B. The building sewer
C. The house drain
D. The lateral branch
Correct Answer: B
Explanation: The building sewer is the portion of drainage piping outside the building that
carries sewage to the public sewer or private disposal system. The building drain is inside the
building up to the foundation wall.
Question 4
,A maintenance technician is called to clear a recurrent blockage in a horizontal drainage line.
The line has no accessible cleanout within 50 feet. What is the most appropriate
recommendation?
A. Install a cleanout at the upstream end of the horizontal line
B. Install a cleanout at the downstream end and at each change of direction exceeding 45
degrees
C. Replace the entire drainage line with a larger diameter pipe
D. Increase the slope of the existing pipe to improve flow
Correct Answer: B
Explanation: Cleanouts are required at the upper end of horizontal drainage lines and at
each aggregate change of direction exceeding 45 degrees. Proper cleanout placement
provides maintenance access and reduces costly demolition for future blockages.
Question 5
A plumbing designer is selecting fittings for a horizontal drainage branch that connects a
water closet to a horizontal drain. Which fitting provides the most hydraulically efficient flow
pattern?
A. Sanitary tee
B. Long-sweep quarter bend
C. Vent tee
D. Double sanitary tee
Correct Answer: B
Explanation: Long-sweep quarter bends provide a gradual direction change that promotes
smooth flow and minimizes turbulence. Sanitary tees are restricted in horizontal drainage
applications because their flow pattern can cause solids accumulation.
, Question 6
A drainage system serving a commercial kitchen receives discharge from a three-
compartment sink, a pre-rinse spray valve, and a dishwasher. The total drainage fixture unit
(DFU) load must be calculated. Which factor most directly determines the required drainage
pipe size?
A. The color and finish of the fixtures
B. The total drainage fixture units and applicable code limitations
C. The water heater temperature setting
D. The number of supply valves installed
Correct Answer: B
Explanation: Drainage sizing is based on the probable discharge load expressed as drainage
fixture units (DFUs), combined with code limitations on maximum DFU per pipe size. Pipe
size is not determined by fixture aesthetics or supply-side components.
Question 7
A plumbing inspector notices that a fixture trap in a laboratory has an excessive depth of
seal. What operational problem can this condition create?
A. Increased resistance to drainage and possible self-siphonage
B. Improved venting performance
C. Increased hot-water circulation
D. Reduced water hammer
Correct Answer: A
Comprehensive Practice Questions with Answers & Detailed
Rationales, 2024 Uniform Plumbing Code, Water Supply, Drainage
and Venting, Pipe Installation, Plumbing Fixtures, Safety Standards,
USVI Licensing Regulations & PSI Exam Preparation
SECTION 1: DRAINAGE SYSTEMS (Questions 1–25)
Question 1
A horizontal drainage pipe serving a residential lavatory must be installed with a minimum
slope. What is the primary engineering purpose of this slope requirement?
A. To increase the water pressure at the fixture outlet
B. To allow gravity to convey wastewater and solids while preventing deposition
C. To reduce the noise transmission through the drainage piping
D. To allow the vent system to function without a loop
Correct Answer: B
Explanation: Proper slope allows gravity to move wastewater and solids through piping while
minimizing blockage. Slope creates velocity sufficient to scour the pipe interior. Insufficient
slope causes solids to settle; excessive slope allows water to outrun solids.
Question 2
During a rough-in inspection of a commercial building, an inspector observes a horizontal
drainage branch installed at a slope of 1/8 inch per foot. The pipe diameter is 2 inches. What
is the most likely code compliance determination?
A. The installation is acceptable because 1/8 inch per foot is the standard minimum for all
diameters
,B. The installation is non-compliant because 2-inch pipe requires 1/4 inch per foot minimum
slope
C. The installation is acceptable because commercial occupancies allow reduced slope
D. The installation is non-compliant because all horizontal drainage requires 1/2 inch per
foot
Correct Answer: B
Explanation: Pipes 2½ inches and smaller require 1/4 inch per foot minimum slope. Pipes 3
inches and larger may use 1/8 inch per foot. Using inadequate slope on small-diameter pipes
causes chronic blockages.
Question 3
A plumbing contractor is installing a building drain that passes through the foundation wall.
The portion of piping outside the building that conveys drainage to the public sewer is
properly termed:
A. The building drain
B. The building sewer
C. The house drain
D. The lateral branch
Correct Answer: B
Explanation: The building sewer is the portion of drainage piping outside the building that
carries sewage to the public sewer or private disposal system. The building drain is inside the
building up to the foundation wall.
Question 4
,A maintenance technician is called to clear a recurrent blockage in a horizontal drainage line.
The line has no accessible cleanout within 50 feet. What is the most appropriate
recommendation?
A. Install a cleanout at the upstream end of the horizontal line
B. Install a cleanout at the downstream end and at each change of direction exceeding 45
degrees
C. Replace the entire drainage line with a larger diameter pipe
D. Increase the slope of the existing pipe to improve flow
Correct Answer: B
Explanation: Cleanouts are required at the upper end of horizontal drainage lines and at
each aggregate change of direction exceeding 45 degrees. Proper cleanout placement
provides maintenance access and reduces costly demolition for future blockages.
Question 5
A plumbing designer is selecting fittings for a horizontal drainage branch that connects a
water closet to a horizontal drain. Which fitting provides the most hydraulically efficient flow
pattern?
A. Sanitary tee
B. Long-sweep quarter bend
C. Vent tee
D. Double sanitary tee
Correct Answer: B
Explanation: Long-sweep quarter bends provide a gradual direction change that promotes
smooth flow and minimizes turbulence. Sanitary tees are restricted in horizontal drainage
applications because their flow pattern can cause solids accumulation.
, Question 6
A drainage system serving a commercial kitchen receives discharge from a three-
compartment sink, a pre-rinse spray valve, and a dishwasher. The total drainage fixture unit
(DFU) load must be calculated. Which factor most directly determines the required drainage
pipe size?
A. The color and finish of the fixtures
B. The total drainage fixture units and applicable code limitations
C. The water heater temperature setting
D. The number of supply valves installed
Correct Answer: B
Explanation: Drainage sizing is based on the probable discharge load expressed as drainage
fixture units (DFUs), combined with code limitations on maximum DFU per pipe size. Pipe
size is not determined by fixture aesthetics or supply-side components.
Question 7
A plumbing inspector notices that a fixture trap in a laboratory has an excessive depth of
seal. What operational problem can this condition create?
A. Increased resistance to drainage and possible self-siphonage
B. Improved venting performance
C. Increased hot-water circulation
D. Reduced water hammer
Correct Answer: A
