1. a) For laboratory results concerning samples from public water supplies and their sources, if any sample is total coliform positive or E. coli-positive, the laboratory shall notify the State regulatory agency that has jurisdiction over the public water supply and the public water supply by the end of the day.
2. b) Presumptive positive microbiological test results are to be reported by the end of the day to State regulatory agency that has jurisdiction over the public water supply as preliminary without waiting for membrane filter verification or multiple tube fermentation (MTF) completion. After membrane filter verification or MTF completion or both, the verified results shall be reported. The State regulatory agency and the public water supply shall be notified when results indicate that non-coliforms may have interfered with the total coliform analysis, as defined in 40 CFR 141.21(c)(2).

3. c) A total coliform-positive result is based on the following:

   1. 1) The confirmed phase if the MTF is used; or
   2. 2) The verified test for the Membrane Filter Technique if M-Endo medium or LES Endo agar is used; or
   3. 3) The required color change - No requirement exists to confirm a total coliform-positive results using Colilert, Colisure, MI agar, E*Colite, m‑ColiBlue24, Readycult, or Colitag test.
4. d) If a sample is found to be E. coli-positive, the sample is to be reported as total coliform-positive, even when total coliform confirmation is negative.

(Source: Amended at 46 Ill. Reg. 19150, effective November 17, 2022)