40 CFR § 141.627 - Requirements for remaining on reduced TTHM and HAA5 monitoring based on subpart L results.

---
identifier: "/us/cfr/t40/s141.627"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 141.627 - Requirements for remaining on reduced TTHM and HAA5 monitoring based on subpart L results."
title_number: 40
title_name: "Protection of Environment"
section_number: "141.627"
section_name: "Requirements for remaining on reduced TTHM and HAA5 monitoring based on subpart L results."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "D"
subchapter_name: "WATER PROGRAMS"
part_number: "141"
part_name: "NATIONAL PRIMARY DRINKING WATER REGULATIONS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-4, 300j-9, and 300j-11."
regulatory_source: "40 FR 59570, Dec. 24, 1975, unless otherwise noted."
cfr_part: "141"
---


# 141.627 Requirements for remaining on reduced TTHM and HAA5 monitoring based on subpart L results.

You may remain on reduced monitoring after the dates identified in § 141.620(c) for compliance with this subpart only if you qualify for a 40/30 certification under § 141.603 or have received a very small system waiver under § 141.604, plus you meet the reduced monitoring criteria in § 141.623(a), and you do not change or add monitoring locations from those used for compliance monitoring under subpart L of this part. If your monitoring locations under this subpart differ from your monitoring locations under subpart L of this part, you may not remain on reduced monitoring after the dates identified in § 141.620(c) for compliance with this subpart.