40 CFR § 142.304 - For which of the regulatory requirements is a small system variance available?

---
identifier: "/us/cfr/t40/s142.304"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 142.304 - For which of the regulatory requirements is a small system variance available?"
title_number: 40
title_name: "Protection of Environment"
section_number: "142.304"
section_name: "For which of the regulatory requirements is a small system variance available?"
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "D"
subchapter_name: "WATER PROGRAMS"
part_number: "142"
part_name: "NATIONAL PRIMARY DRINKING WATER REGULATIONS IMPLEMENTATION"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
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: "41 FR 2918, Jan. 20, 1976, unless otherwise noted."
cfr_part: "142"
---


# 142.304 For which of the regulatory requirements is a small system variance available?

(a) A small system variance is not available under this subpart for a national primary drinking water regulation for a microbial contaminant (including a bacterium, virus, or other organism) or an indicator or treatment technique for a microbial contaminant.

(b) A small system variance under this subpart is otherwise only available for compliance with a requirement specifying a maximum contaminant level or treatment technique for a contaminant with respect to which;

(1) a national primary drinking water regulation was promulgated on or after January 1, 1986; and

(2) the Administrator has published a small system variance technology pursuant to Section 1412(b)(15) of the Act.

Small system variances are not available for public water systems above the pre-1986 maximum contaminant level even if subsequently revised. If the Agency revises a pre-1986 maximum contaminant level and makes it more stringent, then a variance would be available for that contaminant, but only up to the pre-1986 maximum contaminant level.