Hello, Illinois plumbers.

Plumbing contractor registration with IDPH and new homeowner leads in the Chicago area

Cook County, Sep 28 to Nov 6: 3,440 built before 1986

built before 1986

State law makes water utilities replace the whole lead service line, both the public and private sides.

How Illinois licenses plumbers

The Illinois Department of Public Health (IDPH) licenses plumbers under the Illinois Plumbing License Law. Chicago licenses its own plumbers separately. A plumber licensed by Chicago or by IDPH may work anywhere in Illinois. An owner who lives in a single-family home may do its plumbing to the state code, subject to inspection, and anyone hired to help must be licensed. Minor repairs that change no piping to or from fixtures fall outside the act.

Under the act, a city of 500,000 or more may license its own plumbers if it enacts its own ordinance, and the act then stops applying there except where it says otherwise. An IDPH license is valid in Chicago while the plumber's employer holds a Chicago contractor license. Cities and counties that issue permits must check for a valid license or verify the applicant is the owner-occupant of a single-family home.

Chicago plumbing: what the city's own license takes

Anyone who provides plumbing services must put the license number in every advertisement, and the business shows it on its vehicles. Breaking the advertising rule is a Class A misdemeanor with a fine, and IDPH can have the phone number in an unlawful printed ad disconnected. Working or advertising without a license or registration brings a civil penalty for each offense.

Requirements for a plumbing contractor registered with the state

At least one partner or corporate officer must be a licensed plumber, and every employee who does plumbing must be a licensed plumber or apprentice.
Registration as a plumbing contractor with IDPH every year, with an annual fee. Under the act as amended, every registration expires on the last day of September.
General liability, property damage and workers' compensation insurance at the required minimums, in force at all times. A sole proprietorship or partnership with no employees is exempt from the workers' compensation part.
An indemnification bond of $20,000, or a letter of credit for that amount.
A plumber's license expires on April 30. Each renewal after the first requires continuing education.

What the list shows

Each row's buyer side marked a home as their principal residence on the state's real estate transfer declaration.

Where year built is on file, Cook County rows show it. Rows from the other counties do not. A plumber can filter Cook County rows to homes built before 1986, when lead service lines were more common, or any other year. Year built is never a finding that a home has a lead service line.

Days from deed date to the Monday list, Cook County median

In Cook County, the median time from deed date to the Monday list is about 20 days.

The Illinois lead service line law

Under the Lead Service Line Replacement and Notification Act, 415 ILCS 5/17.12, a water supply replacing a lead service line must replace all of it, including the part on private property and the part inside the building up to the first shut-off valve. Partial replacements are banned, both rules effective January 1, 2022.

In an emergency repair, when the building owner can't be reached or the owner or occupant refuses access for a full replacement, the water supply may do a partial replacement. The rest must be replaced within the time the law allows. Lines physically disconnected from the system are exempt.

Built before 1986

Cook County new owners, September 28 to November 6, 2026

Plumbing

Of the Cook County new owners whose year built is on file, 3,440 bought a home built before 1986, which is 74% of that group.

3,440built before 1986Cook County, Sep 28 to Nov 6

Before 1900 229

1900s 182

1910s 232

1920s 430

1930s 91

1940s 218

1950s 736

1960s 619

1970s 548

1980s 300 1986

1990s 372

2000s 466

2010s 92

2020s 143

Testing is the only sure way to find out whether drinking water contains harmful lead. A certified lab test costs $20 to $100.

Homes by year built

Year built	Homes
Before 1900	229
1900s	182
1910s	232
1920s	430
1930s	91
1940s	218
1950s	736
1960s	619
1970s	548
1980s	300
1990s	372
2000s	466
2010s	92
2020s	143

Where new owners are in the Chicago area, Illinois

Sorted by new owners over the last 12 months across six counties

City	New owners, last 90 days90 d	New owners, last 12 months12 mo
Chicago Cook County	5,147	20,538
Naperville DuPage County	451	1,631
Aurora Kane County	433	1,603
Plainfield Will County	397	1,472
Elgin Kane County	323	1,247
Joliet Will County	334	1,237
Schaumburg Cook County	236	858
Arlington Heights Cook County	201	846
Orland Park Cook County	222	841
Des Plaines Cook County	222	834
Palatine Cook County	216	812
Tinley Park Cook County	194	800