Illinois Plumbing Exam Prep

Illinois is one of the few states where plumbing licensing sits with the health department instead of the professional-licensing board. The Illinois Department of Public Health (IDPH), Division of Environmental Health Protection, administers the Illinois Plumbing License Law (225 ILCS 320) and licenses Apprentice Plumbers, journey-level Plumbers, and Plumbing Contractors statewide. IDPH also separately registers Irrigation Contractors and issues a Certified Plumbing Inspector credential.

The path to a Plumber's License runs through the apprenticeship: you must be an Illinois-licensed Apprentice Plumber for at least 4 years before you can sit for the Plumber's License exam. IDPH describes the exam as a state licensing exam rather than one outsourced to a third-party testing vendor. City of Chicago runs its own municipal plumber licensing program in parallel, with a formal reciprocity path for Chicago-licensed plumbers who completed a 4-year licensed apprenticeship to obtain the state license without retaking the exam.

Illinois recognizes the following plumbing credential types, all issued by IDPH:

• Apprentice Plumber's License - Entry-level license; minimum age 16, requires sponsorship by an Illinois-licensed plumber or an approved apprenticeship program. Maximum apprenticeship period is 6 years.
• Plumber's License (journey-level) - The full license, obtained by exam after completing the apprenticeship requirement.
• Plumbing Contractor registration - Required annually for any licensed plumber or apprentice plumber who performs work for another person; requires liability, bodily-injury, and property-damage insurance plus workers' compensation coverage.
• Irrigation Contractor registration - Separate IDPH registration for lawn sprinkler system installers and supervisors.
• Certified Plumbing Inspector - Separate credential with its own examination application.
• Retired Plumber's License - For licensees age 62 or older (or physically unable to continue) who surrender their active license; cannot sponsor apprentices or perform inspections.

The Plumber's License exam is a state-administered licensing exam given directly by IDPH rather than through a third-party testing vendor such as PSI or Pearson VUE. A separate written exam applies to the Certified Plumbing Inspector credential. Question counts, time limits, and format details are not published on the main IDPH plumbing page; review the official Plumber's License Examination Application before your test date.

IDPH does not publish a passing score for the Plumber's License exam on its plumbing program page. Confirm the current passing standard directly with IDPH before your exam date.

To sit for the Illinois Plumber's License exam, IDPH requires:

• At least 4 years employed as an Illinois-licensed Apprentice Plumber (225 ILCS 320/10(d)).
• Completion of at least 2 years of high school or equivalent, plus approved course instruction through a college, university, or trade school.
• For the Apprentice Plumber's License itself: minimum age 16 and sponsorship by an Illinois-licensed plumber or an approved apprenticeship program.

IDPH licenses roughly 8,900 plumbers and 2,000 apprentice plumbers statewide.

Requirements can change. Always confirm current licensing rules with IDPH before applying.

The Plumber's License exam application fee is $175 for Illinois-licensed apprentice plumbers and $225 for applicants licensed in Chicago or out of state, per the official Application for Examination for Plumber's License. A returned-check fee of $100 applies. Always confirm current fee amounts directly with IDPH before submitting payment.

A focused 6 to 8 week study plan works well for most Illinois candidates:

• Week 1-2: Review water supply system fundamentals, including piping materials, sizing, and backflow prevention.
• Week 3-4: Work through drainage and vent system practice problems, including trap and cleanout requirements.
• Week 5-6: Study the Illinois Plumbing Code (77 Ill. Adm. Code Part 890) in depth.
• Week 7-8: Take full-length practice tests, review missed questions, and confirm current exam procedures with IDPH.