---
kind: "unit"
title: "40"
title_heading: "Protection of Environment"
key: "chI/subchN/part421"
level: "part"
label: "Part 421"
heading: "Nonferrous Metals Manufacturing Point Source Category"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/40/chI-subchN-part421"
sections_count: 248
---

# Part 421 — Nonferrous Metals Manufacturing Point Source Category

Title 40 C.F.R. — Protection of Environment › Chapter I — Environmental Protection Agency › Subchapter N — Effluent Guidelines and Standards

## Sections

- [§421.1. Applicability.](/cfr/40/421.1.md)
- [§421.2. Reserved](/cfr/40/421.2.md)
- [§421.3. Monitoring and reporting requirements.](/cfr/40/421.3.md)
- [§421.4. Compliance date for pretreatment standards for existing sources (PSES).](/cfr/40/421.4.md)
- [§421.5. Removal allowances for pretreatment standards.](/cfr/40/421.5.md)

## Contents

- [Subpart A — Bauxite Refining Subcategory](/cfr/40/chI-subchN-part421-subpartA.md)
- [Subpart B — Primary Aluminum Smelting Subcategory](/cfr/40/chI-subchN-part421-subpartB.md)
- [Subpart C — Secondary Aluminum Smelting Subcategory](/cfr/40/chI-subchN-part421-subpartC.md)
- [Subpart D — Primary Copper Smelting Subcategory](/cfr/40/chI-subchN-part421-subpartD.md)
- [Subpart E — Primary Electrolytic Copper Refining Subcategory](/cfr/40/chI-subchN-part421-subpartE.md)
- [Subpart F — Secondary Copper Subcategory](/cfr/40/chI-subchN-part421-subpartF.md)
- [Subpart G — Primary Lead Subcategory](/cfr/40/chI-subchN-part421-subpartG.md)
- [Subpart H — Primary Zinc Subcategory](/cfr/40/chI-subchN-part421-subpartH.md)
- [Subpart I — Metallurgical Acid Plants Subcategory](/cfr/40/chI-subchN-part421-subpartI.md)
- [Subpart J — Primary Tungsten Subcategory](/cfr/40/chI-subchN-part421-subpartJ.md)
- [Subpart K — Primary Columbium-Tantalum Subcategory](/cfr/40/chI-subchN-part421-subpartK.md)
- [Subpart L — Secondary Silver Subcategory](/cfr/40/chI-subchN-part421-subpartL.md)
- [Subpart M — Secondary Lead Subcategory](/cfr/40/chI-subchN-part421-subpartM.md)
- [Subpart N — Primary Antimony Subcategory](/cfr/40/chI-subchN-part421-subpartN.md)
- [Subpart O — Primary Beryllium Subcategory](/cfr/40/chI-subchN-part421-subpartO.md)
- [Subpart P — Primary and Secondary Germanium and Gallium Subcategory](/cfr/40/chI-subchN-part421-subpartP.md)
- [Subpart Q — Secondary Indium Subcategory](/cfr/40/chI-subchN-part421-subpartQ.md)
- [Subpart R — Secondary Mercury Subcategory](/cfr/40/chI-subchN-part421-subpartR.md)
- [Subpart S — Primary Molybdenum and Rhenium Subcategory](/cfr/40/chI-subchN-part421-subpartS.md)
- [Subpart T — Secondary Molybdenum and Vanadium Subcategory](/cfr/40/chI-subchN-part421-subpartT.md)
- [Subpart U — Primary Nickel and Cobalt Subcategory](/cfr/40/chI-subchN-part421-subpartU.md)
- [Subpart V — Secondary Nickel Subcategory](/cfr/40/chI-subchN-part421-subpartV.md)
- [Subpart W — Primary Precious Metals and Mercury Subcategory](/cfr/40/chI-subchN-part421-subpartW.md)
- [Subpart X — Secondary Precious Metals Subcategory](/cfr/40/chI-subchN-part421-subpartX.md)
- [Subpart Y — Primary Rare Earth Metals Subcategory](/cfr/40/chI-subchN-part421-subpartY.md)
- [Subpart Z — Secondary Tantalum Subcategory](/cfr/40/chI-subchN-part421-subpartZ.md)
- [Subpart AA — Secondary Tin Subcategory](/cfr/40/chI-subchN-part421-subpartAA.md)
- [Subpart AB — Primary and Secondary Titanium Subcategory](/cfr/40/chI-subchN-part421-subpartAB.md)
- [Subpart AC — Secondary Tungsten and Cobalt Subcategory](/cfr/40/chI-subchN-part421-subpartAC.md)
- [Subpart AD — Secondary Uranium Subcategory](/cfr/40/chI-subchN-part421-subpartAD.md)
- [Subpart AE — Primary Zirconium and Hafnium Subcategory](/cfr/40/chI-subchN-part421-subpartAE.md)