ICC Commercial Plumbing Inspector P2
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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Question 1
During a rough-in inspection of a commercial building's drainage system, the
contractor has completed the hydrostatic test. What is the minimum required
duration for maintaining the test pressure in a drainage system before it is
concealed?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 30 minutes
Answer: C. 15 minutes
Rationale: The International Plumbing Code requires that a water test be
applied to the drainage system at a minimum pressure equivalent to 10 feet of
head (4.33 psi) above the highest point, and this pressure must be maintained
for at least 15 minutes with no visible leakage. The inspector must verify that all
required tests of installed piping systems are conducted .
Question 2
What is the minimum required separation distance between a water service pipe
and a building sewer pipe when installed in parallel trenches?
,A. 2 feet
B. 3 feet
C. 5 feet
D. 10 feet
Answer: C. 5 feet
Rationale: The IPC requires that water service pipe and building sewer be
separated by 5 feet of undisturbed or compacted earth. Where a water service
pipe crosses a sewer pipe, the water service pipe must be sleeved to at least 5
feet horizontally from the sewer pipe centerline on both sides of the crossing .
Question 3
A commercial building has a water distribution system with a static pressure of 95
psi. What must be installed to protect the system?
A. A pressure relief valve
B. A pressure-reducing valve
C. A check valve
D. A pressure-boosting pump
Answer: B. A pressure-reducing valve
Rationale: The IPC requires that where water pressure exceeds 80 psi, a
pressure-reducing valve must be installed to reduce the pressure to 80 psi or
less. Static pressures above 80 psi can damage fixtures, cause water hammer,
and lead to premature failure of system components .
Question 4
What is the minimum required size for a water service pipe serving a commercial
building?
A. 1/2 inch
B. 3/4 inch
,C. 1 inch
D. 1-1/4 inches
Answer: B. 3/4 inch
Rationale: The IPC requires a minimum water service pipe size of 3/4 inch for
any building. This ensures adequate flow capacity and pressure for building
demands .
Question 5
A gas-fired storage tank-type water heater is installed in a location where water
leakage from the tank will cause damage. The tank must be installed in a pan.
What material is prohibited for construction of this pan?
A. Galvanized steel
B. Aluminum
C. Plastic
D. Any of these materials may be used
Answer: B. Aluminum
Rationale: The IPC prohibits the use of aluminum for water heater pans. Pan
materials must be approved for the application and must be corrosion-resistant.
Galvanized steel and certain plastics are acceptable, but aluminum is not
permitted due to corrosion concerns .
Question 6
What is the minimum required slope for a 4-inch horizontal drainage pipe?
A. 1/4 inch per foot
B. 1/8 inch per foot
C. 1/16 inch per foot
D. Level
, Answer: B. 1/8 inch per foot
Rationale: The IPC requires a minimum slope of 1/8 inch per foot for pipes 3
inches and larger in diameter (3-inch and 4-inch pipes require 1/8 inch per foot
minimum slope). Smaller pipes (2 inches and less) require 1/4 inch per foot
minimum slope .
Question 7
What is the maximum allowable flow rate for a public lavatory faucet at 60 psi?
A. 0.5 gpm
B. 1.0 gpm
C. 1.5 gpm
D. 2.0 gpm
Answer: B. 1.0 gpm
Rationale: The IPC requires that public lavatory faucets have a maximum flow
rate of 1.0 gpm at 60 psi. This water conservation requirement applies to all
public hand-washing facilities .
Question 8
S-traps are:
A. Prohibited in all installations
B. Permitted below grade only
C. Permitted under sinks only
D. Permitted with a vent extension
Answer: A. Prohibited in all installations
Rationale: S-traps are prohibited by the IPC. They are prone to siphonage, which
can break the trap seal and allow sewer gases to enter the building. The modern
P-trap design is the required configuration .
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
Question 1
During a rough-in inspection of a commercial building's drainage system, the
contractor has completed the hydrostatic test. What is the minimum required
duration for maintaining the test pressure in a drainage system before it is
concealed?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 30 minutes
Answer: C. 15 minutes
Rationale: The International Plumbing Code requires that a water test be
applied to the drainage system at a minimum pressure equivalent to 10 feet of
head (4.33 psi) above the highest point, and this pressure must be maintained
for at least 15 minutes with no visible leakage. The inspector must verify that all
required tests of installed piping systems are conducted .
Question 2
What is the minimum required separation distance between a water service pipe
and a building sewer pipe when installed in parallel trenches?
,A. 2 feet
B. 3 feet
C. 5 feet
D. 10 feet
Answer: C. 5 feet
Rationale: The IPC requires that water service pipe and building sewer be
separated by 5 feet of undisturbed or compacted earth. Where a water service
pipe crosses a sewer pipe, the water service pipe must be sleeved to at least 5
feet horizontally from the sewer pipe centerline on both sides of the crossing .
Question 3
A commercial building has a water distribution system with a static pressure of 95
psi. What must be installed to protect the system?
A. A pressure relief valve
B. A pressure-reducing valve
C. A check valve
D. A pressure-boosting pump
Answer: B. A pressure-reducing valve
Rationale: The IPC requires that where water pressure exceeds 80 psi, a
pressure-reducing valve must be installed to reduce the pressure to 80 psi or
less. Static pressures above 80 psi can damage fixtures, cause water hammer,
and lead to premature failure of system components .
Question 4
What is the minimum required size for a water service pipe serving a commercial
building?
A. 1/2 inch
B. 3/4 inch
,C. 1 inch
D. 1-1/4 inches
Answer: B. 3/4 inch
Rationale: The IPC requires a minimum water service pipe size of 3/4 inch for
any building. This ensures adequate flow capacity and pressure for building
demands .
Question 5
A gas-fired storage tank-type water heater is installed in a location where water
leakage from the tank will cause damage. The tank must be installed in a pan.
What material is prohibited for construction of this pan?
A. Galvanized steel
B. Aluminum
C. Plastic
D. Any of these materials may be used
Answer: B. Aluminum
Rationale: The IPC prohibits the use of aluminum for water heater pans. Pan
materials must be approved for the application and must be corrosion-resistant.
Galvanized steel and certain plastics are acceptable, but aluminum is not
permitted due to corrosion concerns .
Question 6
What is the minimum required slope for a 4-inch horizontal drainage pipe?
A. 1/4 inch per foot
B. 1/8 inch per foot
C. 1/16 inch per foot
D. Level
, Answer: B. 1/8 inch per foot
Rationale: The IPC requires a minimum slope of 1/8 inch per foot for pipes 3
inches and larger in diameter (3-inch and 4-inch pipes require 1/8 inch per foot
minimum slope). Smaller pipes (2 inches and less) require 1/4 inch per foot
minimum slope .
Question 7
What is the maximum allowable flow rate for a public lavatory faucet at 60 psi?
A. 0.5 gpm
B. 1.0 gpm
C. 1.5 gpm
D. 2.0 gpm
Answer: B. 1.0 gpm
Rationale: The IPC requires that public lavatory faucets have a maximum flow
rate of 1.0 gpm at 60 psi. This water conservation requirement applies to all
public hand-washing facilities .
Question 8
S-traps are:
A. Prohibited in all installations
B. Permitted below grade only
C. Permitted under sinks only
D. Permitted with a vent extension
Answer: A. Prohibited in all installations
Rationale: S-traps are prohibited by the IPC. They are prone to siphonage, which
can break the trap seal and allow sewer gases to enter the building. The modern
P-trap design is the required configuration .
