US lawIllinoisRegulationsTitle 35 — ENVIRONMENTAL PROTECTIONCHAPTER I: POLLUTION CONTROL BOARDPart 302 — WATER QUALITY STANDARDSSubpart B302.20435 Ill. Adm. Code 302.204pHLast amended: 2023Year: 2026Length: 20 wordsOfficial source Section 302 Section 302.204 pH pH must be within the range of 6.5 to 9.0 except due to natural causes.Previous35 Ill. Adm. Code 302.203Next35 Ill. Adm. Code 302.205