Ill. Admin. Code tit. 77 § 870.140
As specified by the Illinois Plumbing License Law, all plumbing installed in Illinois shall be done by an Illinois licensed plumber or the owner occupant or lessee occupant of a single family residence, or the owner of a single family residence under construction for his or her occupancy and shall comply with the related administrative rules including the Illinois Plumbing Code, Plumbers Licensing Code, and Plumbing Contractor Registration Code. A person who installs plumbing and is not a licensed Illinois plumber or is not the owner occupant or lessee occupant of a single family residence, or the owner of a single family residence under construction for his or her occupancy can be fined up to $5,000 in accordance with the provisions of Illinois Plumbing License Law and the related administrative rules including the Plumbers Licensing Code and Plumbing Contractor Registration Code.
Ill. Admin. Code tit. 77, § 870.140