State plumbing guide · IL
Plumbing in Illinois
Illinois is one of the few states that licenses plumbers and sets a plumbing code at the state level, through the Department of Public Health. The biggest statewide plumbing issue today is lead: Illinois law requires every lead water service line in the state to be replaced.
- Median home built
- 1971
- Built before 1980
- 62%
- Owner-occupied
- 68%
- Winter
- Regular hard freezes
- General statewide rating
- Plumbing code
- State code
- City guides
- 2
Housing figures: U.S. Census Bureau, ACS 2024 1-year (B25035, B25034).
Illinois city plumbing guides
How to check a plumber's license in Illinois
The Illinois Department of Public Health licenses plumbers under the Illinois Plumbing License Law, enforces the Illinois Plumbing Code, and offers a public plumbing license verification tool. [1]
What shapes plumbing in Illinois
Illinois' Lead Service Line Replacement and Notification Act requires community water systems to inventory their service lines and replace every lead service line in the state on set timelines. [3]
Illinois's older housing stock
Statewide, the median home was built in 1971 and 62% of homes predate 1980. Homes like that were usually built with copper supply, early plastic (ABS or PVC) drains, some cast iron. The city guides below show how much that varies within the state.
Which plumbing code applies in Illinois
Chicago maintains its own plumbing code, which it updated in 2021 to align more closely with national model codes while keeping long-standing local requirements. [2]
Seasonal problems to plan for in Illinois
- Winter
- Long freezes. Frozen and burst pipes, frozen outdoor faucets, and sewer lines stressed by frost.
- Spring and summer
- Heavy storms can surcharge combined sewers and back water into basements. See sewer backup.
Regions of Illinois
Chicago area
Lake Michigan water, very old housing, lead service lines and freeze-thaw winters.
Illinois plumbing questions
How do I check a plumber's license in Illinois?
Use the Illinois Department of Public Health's plumbing license verification tool before hiring.
Do I have to replace my lead service line in Illinois?
State law requires water systems to replace all lead service lines over time, and many run programs that coordinate the private side. Ask your water utility what it has on record for your address and what programs apply.
Sources (4)
- U.S. Census Bureau, ACS 2024 1-year (B25035, B25034) · checked 2026-10-01
- Illinois Department of Public Health, Plumbing · checked 2026-10-01
- City of Chicago Department of Buildings, 2021 Amendments to the Chicago Plumbing Code · checked 2026-10-01
- Illinois Environmental Protection Act, 415 ILCS 5/17.12 · checked 2026-10-01