---
title: "Who needs an NPDES permit to discharge pollutants into US waters? Answer in under 100 words. Cite only eCFR (www.ecfr.gov) sources."
canonical: https://www.m-i-n-d.ai/minds/environmental/who-needs-npdes-discharge-permit
jurisdiction: "US Federal"
last_verified: 2026-08-27
license: CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/
attribution: "Source: MIND (m-i-n-d.ai)"
---

# Who needs an NPDES permit to discharge pollutants into US waters? Answer in under 100 words. Cite only eCFR (www.ecfr.gov) sources.

Under 40 CFR 122.1(b)(1), an NPDES permit is required for the discharge of "pollutants" from any "point source" into "waters of the United States," with those three terms defined at 40 CFR 122.2. Owners or operators of any treatment works treating domestic sewage are also subject to NPDES permitting under 40 CFR 122.1(b)(2), whether or not the works would otherwise need a permit, subject to specified statutory exceptions.

## Details / How it works

The NPDES program, implemented under sections 318, 402, and 405 of the Clean Water Act (Public Law 92-500, 33 U.S.C. 1251 et seq.), requires permits for pollutant discharges from point sources into waters of the United States. Part 122 contains the basic EPA permitting requirements, while Parts 123 and 124 address state program approval and permit processing procedures.

## Numbers & thresholds

| Category | Source | Trigger |
|---|---|---|
| Permit required | 40 CFR 122.1(b)(1) | Discharge of "pollutants" from any "point source" into "waters of the United States" |
| Key definitions | 40 CFR 122.2 | Defines "pollutant," "point source," "waters of the United States" |
| Treatment works | 40 CFR 122.1(b)(2) | Owners/operators of any treatment works treating domestic sewage |
| Designation window | 40 CFR 122.1(b)(3) | 180 days to apply after Regional Administrator designation |
| Excluded terms in 122/124 applicability | 40 CFR 122.1(a)(5) | Signal phrase: "Applicable to State programs, see § 123.25" |
| Effective amendments | 40 CFR 122.1 | 65 FR 30904 (May 15, 2000); 72 FR 11211 (Mar. 12, 2007); 84 FR 3336 (Feb. 12, 2019) |

## Exceptions & edge cases

Under 40 CFR 122.1(b)(2), a treatment works treating domestic sewage is exempt from NPDES permitting only if all section 405(d) CWA requirements applicable to it are included in a permit issued under Subtitle C of the Solid Waste Disposal Act, Part C of the Safe Drinking Water Act, the Marine Protection, Research, and Sanctuaries Act of 1972, the Clean Air Act, or an approved State program deemed adequate by the Administrator. The Regional Administrator may also designate any person subject to sewage sludge standards as a treatment works treating domestic sewage where a permit is needed to protect public health and the environment. Nothing precludes more stringent state regulation under Parts 122, 123, or 124.

## Sources

- [1] U.S. Government Publishing Office / Environmental Protection Agency — 40 CFR 122.1 — NPDES permit program — purpose and scope of water discharge permits · https://www.ecfr.gov/current/title-40/section-122.1 · as of 2026-08-27