100+ Free IL Plumber Practice Questions

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Under the IPC as adopted by Illinois, what is the minimum size of a building sewer?

2 inches

3 inches

4 inches

6 inches

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Free Journeyman Plumber Practice Test by State 2026: 4,700+ Questions24 min read

2026 Statistics

Key Facts: IL Plumber Exam

75% average (min 61 each section)

Passing Score

Illinois Department of Public Health (IDPH)

100

Questions

Varies by section limit

$175

Exam Fee

State-administered

IPC

Code Base

Illinois adoption

Illinois's journeyman plumber exam is based on the Illinois State Plumbing Code (SPC) and administered by IDPH. It uses a unique 3-part format: written knowledge test, drawing interpretation, and practical demonstration. The Illinois SPC is distinct from both the IPC and UPC. The exam requires a 75% average with a minimum 61% on each section.

Sample IL Plumber Practice Questions

Try these sample questions to test your IL Plumber exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the IPC as adopted by Illinois, what is the minimum size of a building sewer?

A.2 inches

B.3 inches

C.4 inches

D.6 inches

Explanation: Per IPC building sewer requirements, the minimum size is 3 inches under the IPC. This ensures adequate capacity for the building drainage load and allows for proper maintenance access.

2Per the IPC as adopted by Illinois, what is the minimum slope for a 4-inch horizontal drainage pipe?

A.1/16 inch per foot

B.1/8 inch per foot

C.1/4 inch per foot

D.1/2 inch per foot

Explanation: Per IPC drainage slope tables, horizontal drainage pipes 3 inches and larger require a minimum slope of 1/8 inch per foot. This ensures adequate velocity (approximately 2 fps) to transport solids through the drainage system.

3What is the DFU value for a residential water closet (1.6 gpf) under the IPC?

A.2 DFU

B.3 DFU

C.4 DFU

D.6 DFU

Explanation: Per IPC fixture unit tables, a residential water closet with 1.6 gpf is rated at 3 DFU. This value is used for drainage and vent pipe sizing calculations throughout the plumbing system.

4Per the IPC as adopted by Illinois, what is the maximum distance between cleanouts on a horizontal drainage pipe?

A.50 feet

B.75 feet

C.100 feet

D.150 feet

Explanation: Per IPC cleanout requirements, cleanouts must be installed at intervals not exceeding 100 feet on horizontal drainage lines. Proper cleanout spacing ensures the entire system can be maintained and cleared of blockages.

5Under Illinois regulations, what type of backflow preventer is required for a high-hazard cross-connection?

A.Atmospheric vacuum breaker (AVB)

B.Pressure vacuum breaker (PVB)

C.Double check valve assembly (DCVA)

D.Reduced pressure zone (RPZ) assembly

Explanation: Per IPC backflow prevention requirements, a reduced pressure zone (RPZ) assembly is required for high-hazard cross-connections. The RPZ provides the highest level of protection with a relief valve between two check valves.

6Per the IPC as adopted by Illinois, what is the minimum water supply pipe size for a bathtub with shower?

A.3/8 inch

B.1/2 inch

C.3/4 inch

D.1 inch

Explanation: Per IPC fixture supply sizing tables, the minimum supply pipe size for a bathtub with shower is 1/2 inch. This ensures adequate flow and pressure at the fixture for proper operation.

7What is the maximum water temperature setting for a residential water heater per the IPC?

A.110°F

B.120°F

C.140°F

D.180°F

Explanation: Per IPC hot water requirements, the maximum delivery temperature at residential fixtures is 120°F. Anti-scald devices or thermostatic mixing valves must limit output temperature to prevent burns.

8Per the IPC as adopted by Illinois, what is the minimum trap seal depth for a standard plumbing fixture?

A.1 inch

B.2 inches

C.3 inches

D.4 inches

Explanation: Per IPC trap requirements, the minimum trap seal depth is 2 inches and the maximum is 4 inches. The water seal prevents sewer gases from entering the building through fixture drains.

9Under the IPC as adopted by Illinois, what is the minimum vent pipe size?

A.3/4 inch

B.1 inch

C.1-1/4 inches

D.1-1/2 inches

Explanation: Per IPC venting requirements, the minimum vent pipe size is 1-1/4 inches. No vent pipe shall be less than 1-1/4 inches in diameter. The vent must also be at least one-half the diameter of the drain it serves.

10Per the IPC as adopted by Illinois, what is the maximum static water pressure in a building distribution system?

A.60 psi

B.80 psi

C.100 psi

D.125 psi

Explanation: Per IPC water pressure requirements, water pressure shall not exceed 80 psi static. Where pressures exceed 80 psi, a pressure-reducing valve must be installed to prevent fixture damage and pipe noise.

About the IL Plumber Exam

Illinois journeyman plumber exam is state-administered by IDPH. Unique 3-part format: written knowledge, drawing interpretation, and practical skills. Based on the Illinois State Plumbing Code (SPC). Requires 75% average with minimum 61% on each section.

Questions

100 scored questions

Time Limit

Varies by section

Passing Score

75% average (min 61 each section)

Exam Fee

$175 (Illinois Department of Public Health (IDPH))

IL Plumber Exam Content Outline

25%

Drainage & Waste Systems

Drain sizing, DFU calculations, slope requirements, cleanouts per SPC

20%

Water Supply & Distribution

Pipe sizing, backflow prevention, water heaters, pressure regulation per SPC

20%

Venting Systems

Vent sizing, wet venting, AAVs, vent termination, circuit venting per SPC

15%

Gas Piping

Gas pipe sizing, appliance venting, pressure testing, BTU calculations per IFGC

20%

Fixtures, Materials & Illinois Code

Fixture installation, materials, joints, permits, inspections, and Illinois-specific requirements

How to Pass the IL Plumber Exam

What You Need to Know

Passing score: 75% average (min 61 each section)
Exam length: 100 questions
Time limit: Varies by section
Exam fee: $175

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

IL Plumber Study Tips from Top Performers

1Master IPC drainage fixture unit (DFU) values and pipe sizing tables

2Study backflow prevention device selection and cross-connection control

3Memorize minimum pipe sizes, slopes, and clearances for common fixtures

4Practice gas pipe sizing calculations using IFGC tables

5Understand wet venting and circuit venting provisions in the IPC

6Learn Illinois-specific permit and inspection requirements

Frequently Asked Questions

What code does Illinois use for the plumber exam?

Illinois uses the Illinois Plumbing Code (SPC). The exam covers drainage, venting, water supply, gas piping, and fixture requirements as adopted by the state.

Who administers the Illinois plumber exam?

The exam is administered by State-administered under the Illinois Department of Public Health (IDPH).

How many questions are on the Illinois plumber exam?

The Illinois plumber exam has approximately 100 questions with a Varies by section time limit. A score of 75% average (min 61 each section) is required to pass.

Is the IL plumber exam open book?

Most State-administered-administered plumber exams allow a bound copy of the adopted code. Check with the Illinois Department of Public Health (IDPH) for approved reference materials.