eCFR Reference Browser

---

title: "40 CFR §141.534"

source: "https://www.ecfr.gov/current/title-40/section-141.534"

title_number: "40"

volume_number: "25"

chapter_number: "Unknown"

subchapter_code: "D"

subchapter_subject: "WATER PROGRAMS (CONTINUED)"

part_code: "141"

part_subject: "NATIONAL PRIMARY DRINKING WATER REGULATIONS"

subpart_code: "T"

subpart_subject: "Enhanced Filtration and Disinfection—Systems Serving Fewer Than 10,000 People"

section_number: "141.534"

section_subject: "How does my system use this data to calculate an inactivation ratio?"

cfr_reference: "40 CFR 141.534"

title_name: "Title 40"

title_subject: "Protection of Environment"

parts_covered: "Parts 136 to 149"

revised_date: "Revised as of July 1, 2019"

publication_date: "As of July 1, 2019"

contains_description: "Containing a codification of documents of general applicability and future effect"

publication_info: "Published by the Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"

---

Use the tables in § 141.74(b)(3)(v) to determine the appropriate CT99.9 value. Calculate the total inactivation ratio as follows, and multiply the value by 3.0 to determine log inactivation of Giardia lamblia:

§141.534 - How does my system use this data to calculate an inactivation ratio?