225 ILCS 320/40
All persons engaged in plumbing as defined in this Act shall comply with the minimum code of standards for plumbing and the fixtures, materials, design and installation methods of plumbing systems published by the Department and filed with the Secretary of State as required by this Act.
All installations of equipment, fixtures, appliances or piping which are used or intended for use entirely for or as a part of a water supply system or sewage disposal system and thereby can affect the public health shall comply with the provisions of the State Plumbing Code for design, materials, installation and maintenance. The installation, repair, maintenance, alteration or extension of building sewers shall be done in accordance with the State Plumbing Code. Any person engaged in any of such work shall upon investigation and determination of non-compliance with the provisions of the State Plumbing Code be subject to the penalties contained in this Act. Such prosecution shall be the responsibility of the State's Attorney or other authority as authorized by this Act.
225 ILCS 320/40