Ill. Admin. Code tit. 35, § 302.306
Notwithstanding the provisions of Section 302.209, at no time shall the geometric mean, based on a minimum of five samples taken within a 30-day period, of fecal coliform exceed 2000 per 100 ml.
(Source: Amended at 47 Ill. Reg. 4437, effective March 23, 2023)