Illinois Plumbing Code PracticeUltimate
Exam
**Question 1.** Which Illinois Plumbing Code provision requires a licensed
plumber to obtain a permit before installing a new water supply system in a
commercial building?
A) Section 102.1 – General Permit Requirements
B) Section 104.3 – Scope of Licensed Work
C) Section 108.5 – Inspection and Testing
D) Section 110.2 – Contractor Licensing
Answer: A
Explanation: Section 102.1 outlines the mandatory permit process for any new
water supply installation, ensuring the work is reviewed before construction
begins.
**Question 2.** In the Illinois Plumbing Code, the term “developed length” refers
to:
A) The total length of pipe measured along its centerline, including fittings.
B) The length of pipe that actually carries water, excluding fittings.
C) The length of pipe after accounting for expansion due to temperature.
D) The length of pipe required for pressure testing.
Answer: B
Explanation: “Developed length” is defined as the straight-run length of pipe that
conveys water, not counting the added length contributed by elbows, tees, or
other fittings.
,Illinois Plumbing Code PracticeUltimate
Exam
**Question 3.** According to the Illinois Code, which fixture is prohibited in a
public restroom?
A) Floor-drain with a grate
B) Trough urinal without a flush valve
C) Water-saving dual-flush toilet
D) Sensor-activated faucet
Answer: B
Explanation: Trough urinals lacking an integrated flush valve are prohibited
because they cannot be reliably controlled for water conservation and hygiene.
**Question 4.** For an assembly occupancy (e.g., a theater) with a maximum
occupant load of 500, the minimum number of water closets required per the
Illinois Plumbing Code is:
A) 10
B) 15
C) 20
D) 25
Answer: C
Explanation: Table 403.2 of the code requires one water closet per 50 occupants
for assembly use; 500 ÷ 50 = 10, but the code also mandates a minimum of 20 for
large assemblies, thus 20 is required.
,Illinois Plumbing Code PracticeUltimate
Exam
**Question 5.** Which of the following back-flow prevention devices is
mandated for a fire sprinkler system serving a public building in Illinois?
A) Double-check valve (DCV)
B) Atmospheric vacuum breaker (AVB)
C) Reduced Pressure Zone (RPZ) valve
D) Pressure vacuum breaker (PVB)
Answer: C
Explanation: RPZ valves provide the highest level of protection and are required
for fire-sprinkler systems where cross-connection risk is high.
**Question 6.** When sizing a water supply pipe using Water Supply Fixture
Units (WSFUs), which factor is NOT considered in the Illinois Plumbing Code
tables?
A) Available pressure at the point of delivery
B) Pipe material roughness coefficient
C) Anticipated future building expansion
D) Desired flow velocity
Answer: C
Explanation: The code tables consider pressure, roughness, and velocity to
determine pipe size; future expansion is a design consideration but not part of the
sizing tables.
, Illinois Plumbing Code PracticeUltimate
Exam
**Question 7.** The maximum allowable temperature for domestic hot water
storage tanks in Illinois is:
A) 120 °F (49 °C)
B) 140 °F (60 °C)
C) 160 °F (71 °C)
D) 180 °F (82 °C)
Answer: B
Explanation: The code limits hot-water storage temperature to 140 °F to reduce
scald risk while still providing adequate temperature for sanitizing.
**Question 8.** In a drainage system, the minimum trap seal depth required by
the Illinois Plumbing Code is:
A) 1 inch (25 mm)
B) 2 inches (50 mm)
C) 3 inches (75 mm)
D) 4 inches (100 mm)
Answer: B
Explanation: A 2-inch (50 mm) seal depth is the minimum to prevent sewer gases
from entering occupied spaces.
**Question 9.** Which vent configuration is specifically prohibited for a fixture
located more than 6 ft from the nearest vertical stack?
A) Individual vent
Exam
**Question 1.** Which Illinois Plumbing Code provision requires a licensed
plumber to obtain a permit before installing a new water supply system in a
commercial building?
A) Section 102.1 – General Permit Requirements
B) Section 104.3 – Scope of Licensed Work
C) Section 108.5 – Inspection and Testing
D) Section 110.2 – Contractor Licensing
Answer: A
Explanation: Section 102.1 outlines the mandatory permit process for any new
water supply installation, ensuring the work is reviewed before construction
begins.
**Question 2.** In the Illinois Plumbing Code, the term “developed length” refers
to:
A) The total length of pipe measured along its centerline, including fittings.
B) The length of pipe that actually carries water, excluding fittings.
C) The length of pipe after accounting for expansion due to temperature.
D) The length of pipe required for pressure testing.
Answer: B
Explanation: “Developed length” is defined as the straight-run length of pipe that
conveys water, not counting the added length contributed by elbows, tees, or
other fittings.
,Illinois Plumbing Code PracticeUltimate
Exam
**Question 3.** According to the Illinois Code, which fixture is prohibited in a
public restroom?
A) Floor-drain with a grate
B) Trough urinal without a flush valve
C) Water-saving dual-flush toilet
D) Sensor-activated faucet
Answer: B
Explanation: Trough urinals lacking an integrated flush valve are prohibited
because they cannot be reliably controlled for water conservation and hygiene.
**Question 4.** For an assembly occupancy (e.g., a theater) with a maximum
occupant load of 500, the minimum number of water closets required per the
Illinois Plumbing Code is:
A) 10
B) 15
C) 20
D) 25
Answer: C
Explanation: Table 403.2 of the code requires one water closet per 50 occupants
for assembly use; 500 ÷ 50 = 10, but the code also mandates a minimum of 20 for
large assemblies, thus 20 is required.
,Illinois Plumbing Code PracticeUltimate
Exam
**Question 5.** Which of the following back-flow prevention devices is
mandated for a fire sprinkler system serving a public building in Illinois?
A) Double-check valve (DCV)
B) Atmospheric vacuum breaker (AVB)
C) Reduced Pressure Zone (RPZ) valve
D) Pressure vacuum breaker (PVB)
Answer: C
Explanation: RPZ valves provide the highest level of protection and are required
for fire-sprinkler systems where cross-connection risk is high.
**Question 6.** When sizing a water supply pipe using Water Supply Fixture
Units (WSFUs), which factor is NOT considered in the Illinois Plumbing Code
tables?
A) Available pressure at the point of delivery
B) Pipe material roughness coefficient
C) Anticipated future building expansion
D) Desired flow velocity
Answer: C
Explanation: The code tables consider pressure, roughness, and velocity to
determine pipe size; future expansion is a design consideration but not part of the
sizing tables.
, Illinois Plumbing Code PracticeUltimate
Exam
**Question 7.** The maximum allowable temperature for domestic hot water
storage tanks in Illinois is:
A) 120 °F (49 °C)
B) 140 °F (60 °C)
C) 160 °F (71 °C)
D) 180 °F (82 °C)
Answer: B
Explanation: The code limits hot-water storage temperature to 140 °F to reduce
scald risk while still providing adequate temperature for sanitizing.
**Question 8.** In a drainage system, the minimum trap seal depth required by
the Illinois Plumbing Code is:
A) 1 inch (25 mm)
B) 2 inches (50 mm)
C) 3 inches (75 mm)
D) 4 inches (100 mm)
Answer: B
Explanation: A 2-inch (50 mm) seal depth is the minimum to prevent sewer gases
from entering occupied spaces.
**Question 9.** Which vent configuration is specifically prohibited for a fixture
located more than 6 ft from the nearest vertical stack?
A) Individual vent
