{"data":{"id":"us/40-cfr-141.533","jurisdiction":"us","citation":"40 CFR 141.533","heading":"What data must my system collect to calculate a disinfection profile?","body":"Your system must monitor the following parameters to determine the total log inactivation using the analytical methods in § 141.74 (a), once per week on the same calendar day, over 12 consecutive months:\n(a) The temperature of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow;\n(b) If your system uses chlorine, the pH of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow;\n(c) The disinfectant contact time(s) (“T”) during peak hourly flow; and\n(d) The residual disinfectant concentration(s) (“C”) of the water before or at the first customer and prior to each additional point of disinfection during peak hourly flow.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER D—WATER PROGRAMS","PART 141—NATIONAL PRIMARY DRINKING WATER REGULATIONS","Subpart T—Enhanced Filtration and Disinfection—Systems Serving Fewer Than 10,000 People"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"41d6df56eef05dddcd66773111da1a869b5493116bf02f67f236bdf501a73108","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-141.532","next":"us/40-cfr-141.534"},"notice":"GroundRules: Original legal text. Not legal advice."}