TITLE 77: PUBLIC HEALTHHome
PART 890 ILLINOIS PLUMBING CODE
CHAPTER I: DEPARTMENT OF PUBLIC HEALTH
SECTION 890.1040 AIR GAPS
Section 890.1040 Air Gaps
The air gap between an indirect waste and the drainage system shall be at least two (2) times the diameter of the fixture drain or drainage pipe served, but shall never be less than one (1) inch. For requirements in excess of this minimum, see Appendix A: Table C, and Appendix H: Illustration F.