Disclaimer 

Introduction to the National Pretreatment Program 

DISCLAIMER

The discussion in this document is intended solely as a summary of existing guidance. This 

document is not a regulation, nor does it substitute for any requirements under the Clean Water 

Act (CWA) or U.S. Environmental Protection Agency’s (EPA’s) regulations. Thus, it does not 

impose legally binding requirements on EPA, states, municipalities, or the regulated community. The 

general descriptions provided in this document might not apply to a particular situation based on the 

circumstances. This document does not confer legal rights or impose legal obligations on any member of 

the public. 

Among other things, the document describes existing requirements with respect to industrial 

dischargers and publicly owned treatment works (POTWs) under the CWA and its implementing 

regulations at Title 40 of the Code of Federal Regulations, Parts 122, 123, 124, and 403 and chapter I, 

subchapter N. Although EPA has made every effort to ensure the accuracy of the discussion in this 

document, a discharger’s obligations are determined, in the case of directly discharging POTWs, by the 

terms of its National Pollutant Discharge Elimination System permit and EPA’s regulations or, in the case 

of indirect dischargers, by permits or equivalent control mechanisms issued to POTW industrial users or 

by regulatory requirements. Nothing in this document changes any statutory or regulatory requirement. If 

a conflict arises between this document’s content and any permit or regulation, the permit or regulation 

would be controlling. EPA and local decision makers retain the discretion to adopt approaches on a caseby-case basis that differ from those described in this document where appropriate and authorized by EPA 

regulations, state law, or local ordinances. 

Mention of trade names or commercial products does not constitute endorsement or 

recommendation for their use. 

This document is current as of March 2011. EPA may decide to revise this document without 

public notice to reflect changes in the Agency’s approach to implementing pretreatment standards or to 

clarify and update text. To determine whether EPA has revised or supplemented the information in this 

document, access the document at http://www.epa.gov/npdes/pretreatment. 
Contents 

CONTENTS

CHAPTER 1. POTWs and the Need for the Pretreatment Program....................................................1-1

Sewage Treatment...........................................................................................................................1-1

Need for the Pretreatment Program.................................................................................................1-2

CHAPTER 2. Overview of the National Pretreatment Program ...........................................................2-1

The Clean Water Act........................................................................................................................2-1

The General Pretreatment Regulations ...........................................................................................2-2

POTW Pretreatment Programs........................................................................................................2-5

Attachment 2-1: State and Territory Program Authorization Status.................................................2-8

CHAPTER 3. Pretreatment Standards .................................................................................................3-1

Prohibited Discharge Standards ......................................................................................................3-2

Effluent Guidelines and Categorical Pretreatment Standards Development...................................3-2

Local Limits ......................................................................................................................................3-6

Summary of Standards ....................................................................................................................3-8

Attachment 3-1: Summary of Categorical Standards.......................................................................3-9

CHAPTER 4. POTW Pretreatment Program Responsibilities..............................................................4-1

Legal Authority .................................................................................................................................4-1

Industrial Waste Surveys .................................................................................................................4-2

IU Permits/Control Mechanisms.......................................................................................................4-3

Inspections .......................................................................................................................................4-5

Sampling ..........................................................................................................................................4-7

Control Authority Enforcement.........................................................................................................4-9

Program Management and Record Keeping .................................................................................4-12

Public Participation.........................................................................................................................4-13

POTW Reporting............................................................................................................................4-14

Approval Authority Enforcement ....................................................................................................4-15

CHAPTER 5. Industrial User Pretreatment Program Responsibilities .................................................5-1

Reporting Requirements ..................................................................................................................5-1

Categorical Industrial User Reporting Requirements.............................................................5-2

Significant Industrial User Reporting Requirements...............................................................5-5

Signatory and Certification Requirements [40 CFR 403.12(l)]...............................................5-7

Cross-Media Electronic Reporting [40 CFR Part 3]................................................................5-7

Self-Monitoring Requirements..........................................................................................................5-8

Notification Requirements ..............................................................................................................5-10

Notification of Production Level Change in the Equivalent Limit Calculation [40 CFR 

403.6(c)(9)]........................................................................................................................5-10

Notification of Material/Significant Change in the Alternative Limit Calculation [40 CFR 

403.6(e)]............................................................................................................................5-10

Notification of Waived Pollutant Present [40 CFR 403.12(e)(2)(vi)].....................................5-11

Notification of Middle-Tier Categorical Industrial User 40 CFR 403.12(e)(3)(iv)].................5-11

Notification of Potential Problems Including Slug Loading [40 CFR 403.12(f)]....................5-11

Noncompliance Notification and Repeat Sampling Report [40 CFR 403.12(g)(2)]..............5-11

Notification of Changed Discharge [40 CFR 403.12(j) and 40 CFR 122.42(b)]...................5-11

Notification of Discharge of Hazardous Wastes [40 CFR 403.12(p)]...................................5-11

Notification of Upset [40 CFR 403.16]..................................................................................5-12

Introduction to the National Pretreatment Program i 
Contents 

ii Introduction to the National Pretreatment Program 

Notification of Bypass [40 CFR 403.17] ...............................................................................5-12

Record-Keeping Requirements......................................................................................................5-12

Attachment 5-1: Summary of Reporting and Notification Requirements for All IUs ......................5-13

Attachment 5-2: Summary of Notification and Citation Requirements That Might Not Apply to 

All IUs..........................................................................................................................................5-15

CHAPTER 6. Hauled Wastes...............................................................................................................6-1

Nature of Hauled Wastes .................................................................................................................6-1

Control Programs .............................................................................................................................6-2

Concerns..........................................................................................................................................6-3

CHAPTER 7. Pollution Prevention .......................................................................................................7-1

P2 and the Pretreatment Program ...................................................................................................7-3

Key Elements of a Successful POTW P2 Program .........................................................................7-4

Benefits of P2 for POTWs ................................................................................................................7-4

Benefits of P2 for IUs .......................................................................................................................7-5

Water Conservation as P2 ...............................................................................................................7-6

Potential Impediments to P2 ............................................................................................................7-7

P2 Assistance...................................................................................................................................7-8
Preface 

Introduction to the National Pretreatment Program iii 

PREFACE

The industrialization of the United States brought with it a level of pollution never before seen in 

the country. By the 1960s scenes of dying fish and burning rivers were repeated regularly on the evening 

news. In response to such critical environmental problems, in December 1970 the President of the United 

States created the U.S. Environmental Protection Agency (EPA) by executive order. 

In 1972 Congress passed the Federal Water Pollution Control Act, also know as the Clean Water 

Act (CWA), to restore and maintain the integrity of the nation’s waters. The goals of the CWA are to 

eliminate the introduction of pollutants into the nation’s navigable waters and to achieve fishable and 

swimmable water quality levels. The CWA’s National Pollutant Discharge Elimination System (NPDES) 

Permit Program represents one of the key components established to accomplish the goals of the CWA. 

The NPDES Permit Program generally requires that point source discharges of pollutants to waters of the 

United States, i.e., direct dischargers, obtain an NPDES permit.1

 The CWA also established substantial 

penalty authority for noncompliance with NPDES permits. 

In addition to addressing these direct discharges, the CWA also established a regulatory program 

to address indirect discharges from industries to publicly owned treatment works (POTWs) through the 

National Pretreatment Program, a component of the NPDES Permit Program. The National Pretreatment 

Program requires industrial and commercial dischargers, called industrial users (IUs), to obtain permits or 

other control mechanisms to discharge wastewater to the POTW. Such a permit may specify the effluent 

quality that necessitates that an IU pretreat or otherwise control pollutants in its wastewater before 

discharging it to a POTW. 

Certain industrial discharge practices can interfere with the operation of POTWs, leading to the 

discharge of untreated or inadequately treated wastewater into rivers, lakes, and other waters of the 

United States. A discharge that causes interference inhibits or disrupts the POTW, its treatment processes 

or operations, or its sludge processes, use, or disposal and therefore causes a violation of any requirement 

of the POTW's NPDES permit. Some pollutants are not amenable to biological wastewater treatment at 

POTWs and can pass through the treatment plant untreated. This pass through of pollutants affects the 

receiving water and might cause fish kills or other deleterious effects. Even when a POTW has the 

capability to remove toxic pollutants from wastewater, the pollutants can end up in the POTW’s sewage 

sludge, which might then be processed into a fertilizer or soil conditioner that is land-applied to food 

crops, parks, or golf courses or elsewhere. 

The General Pretreatment Regulations of the National Pretreatment Program require all large 

POTWs (those designed to treat flows of more than 5 million gallons per day) and smaller POTWs (that 

accept wastewater from IUs that could affect the treatment plant or its discharges) to establish local 

pretreatment programs. These local programs must enforce all national pretreatment standards and 

requirements in addition to any more stringent local requirements necessary to protect site-specific 

conditions at the POTW. Approximately 1,600 POTWs have developed and are implementing local 

pretreatment programs designed to control discharges from approximately 23,000 significant IUs. 

Since the promulgation of the General Pretreatment Regulations in1983, the National 

Pretreatment Program has made great strides in reducing the introduction of toxic pollutants to sewer 

systems and to waters of the United States. In the eyes of many, the National Pretreatment Program—

implemented as a partnership between EPA, states, and POTWs—is a notable success among efforts to 

 

1

 Some point sources, however, are not required to obtain NPDES permits; see Title 40 of the Code of Federal Regulations

(CFR), section 122.3, Exclusions. 
Preface 

iv Introduction to the National Pretreatment Program 

reduce the effects of pollution on human health and the environment. Such strides can be attributed to the 

efforts of many federal, state, local, and industrial representatives who have been involved with 

developing and implementing the various aspects of the National Pretreatment Program. 

EPA has supported the National Pretreatment Program by developing numerous guidance 

manuals. In fact, it has released more than 40 manuals providing guidance to EPA, states, POTWs, and 

industry on various National Pretreatment Program requirements and policy determinations. Through 

such guidance, the National Pretreatment Program has maintained national consistency in interpreting the 

regulations. 

Nonetheless, turnover in National Pretreatment Program staff has diluted historical knowledge, 

and new staff and other interested parties might be unfamiliar with existing guidance materials. With this 

in mind, the intent of this guidance manual, Introduction to the National Pretreatment Program, is to 

 Provide a reference for anyone interested in understanding the basics of National 

Pretreatment Program requirements 

 Provide a road map to additional and more detailed guidance materials for those trying to 

implement specific elements of the National Pretreatment Program. 

This guidance manual is intended to explain the basic concepts that shape the National 

Pretreatment Program, discuss the current status of the program and program guidance, and serve as a tool 

for pretreatment program implementation. 

The manual is organized to provide an overview of program requirements and to refer the reader 

to more detailed EPA guidance on specific program elements. To help the reader, the first page of each 

chapter contains a list of EPA references applicable to the topics discussed in that chapter. Electronic 

versions of the documents listed are available through EPA’s website at 

http://www.epa.gov/npdes/pretreatment. 
List Acronyms and Abbreviations 

ACRONYMS AND ABBREVIATIONS

AHL Allowable Headworks Loading 

BAT Best Available Technology Economically Achievable 

BCT Best Conventional Pollutant Control Technology 

BMP Best Management Practice 

BMR Baseline Monitoring Report 

BOD Biochemical Oxygen Demand 

BOD5 5-day Biochemical Oxygen Demand 

BPT Best Practicable Control Technology Currently Available 

CDX Central Data Exchange 

CFR Code of Federal Regulations

CIU Categorical Industrial User 

CROMERR Cross-Media Electronic Reporting Rule 

CSO Combined Sewer Overflow 

CWA Clean Water Act 

CWF Combined Wastestream Formula 

ELG Effluent Limitations Guideline 

EPA [U.S.] Environmental Protection Agency 

ERG Enforcement Response Guide 

ERP Enforcement Response Plan 

FDF Fundamentally Different Factors 

FOG Fats, Oils, and Grease 

FR Federal Register 

FWA Flow-Weighted Average 

gpd Gallons per Day 

IU Industrial User 

IWS Industrial Waste Survey 

MAHL Maximum Allowable Headworks Loading 

MAIL Maximum Allowable Industrial Loading 

mg/L Milligrams per Liter 

mgd Million Gallons per Day 

MTCIU Middle-Tier Categorical Industrial User 

NAICS North American Industry Classification System (replaced Standard Industrial 

Classification [SIC] system) 

NOV Notice of Violation 

NPDES National Pollutant Discharge Elimination System 

NSCIU Nonsignificant Categorical Industrial User 

NSPS New Source Performance Standard 

OPPT Office of Pollution Prevention and Toxics (EPA) 

P2 Pollution Prevention 

Introduction to the National Pretreatment Program v 
List of Acronyms and Abbreviations 

vi Introduction to the National Pretreatment Program 

PCBs Polychlorinated Biphenyls 

POTW Publicly Owned Treatment Works 

PPA Pollution Prevention Act of 1990 

PSES Pretreatment Standards for Existing Sources 

PSNS Pretreatment Standards for New Sources 

RCRA Resource Conservation and Recovery Act 

SIC Standard Industrial Classification (replaced by NAICS) 

SIU Significant Industrial User 

SNC Significant Noncompliance 

SUO Sewer Use Ordinance 

TOMP Toxic Organic Management Program 

TRE Toxicity Reduction Evaluation 

TRC Technical Review Criteria 

TSS Total Suspended Solids 

TTO Total Toxic Organics 

U.S.C. United States Code 

WQS Water Quality Standard 

WET Whole Effluent Toxicity 
Glossary 

GLOSSARY OF TERMS

This glossary defines and explains each term used in this manual. To the extent that the 

definitions and explanations provided in this glossary differ from those in EPA regulations or other 

official documents, the definitions used in this glossary are intended for use in understanding this manual 

only. 

Act or “the act” [40 CFR 403.3(b)]

The Federal Water Pollution Control Act, also known as the Clean Water Act (CWA), as amended, 

Title 33 of the United States Code (U.S.C.), sections 1251 et seq. 

Allowable Headworks Loading (AHL) 

The estimated maximum loading of a pollutant that can be received at a POTW’s headworks and not 

cause a POTW to violate a particular treatment plant or environmental criterion. AHLs are developed 

to prevent interference or pass through. 

Approval Authority [40 CFR 403.3(c)]

The director in an NPDES Authorized State with an approved state pretreatment program, or the 

appropriate EPA regional administrator in a non-NPDES Authorized State or NPDES state without an 

approved state pretreatment program. 

Approved POTW pretreatment program or program [40 CFR 403.3(d)] 

A program administered by a POTW that meets the criteria established in 40 CFR Part 403 and that 

has been approved by a regional administrator or state director. 

Approved state pretreatment program 

A program administered by a state that meets the criteria established in 40 CFR 403.10 and that has 

been approved by a regional administrator. 

Approved/Authorized state 

A state with an NPDES permit program approved pursuant to CWA section 402(b) and an approved 

state pretreatment program. 

Baseline Monitoring Report (BMR) [paraphrased from 40 CFR 403.12(b)] 

A report submitted by categorical industrial users (CIUs) within 180 days after the effective date of 

an applicable categorical pretreatment standard—or at least 90 days before beginning discharge for 

new sources—that contains specific facility information, including flow and pollutant concentration 

data. For existing sources, the report must also certify as to the compliance status of the facility with 

respect to the categorical pretreatment standards. 

Best Available Technology Economically Achievable (BAT) 

A level of technology based on the best available control and treatment measures that are 

economically achievable within a given industrial category or subcategory. 

Best Management Practice (BMP) [40 CFR 403.3(e)] 

A schedule of activities, prohibition of practices, maintenance procedures, and other management 

practices to implement the prohibitions listed in 40 CFR 403.5(a)(1) and (b). BMPs also include 

treatment requirements, operating procedures, and practices to control plant site runoff, spillage or 

leaks, sludge or waste disposal, or drainage from raw materials storage. 

Introduction to the National Pretreatment Program vii 
Glossary 

Best Practicable Control Technology Currently Available (BPT) 

A level of technology represented by, typically, the average of the best practicable wastewater 

treatment performance levels currently available within a given industrial category or subcategory. 

Biochemical Oxygen Demand (5-day) (BOD5) 

An indirect measure of the concentration of biologically degradable material present in organic 

wastes. It reflects the amount of oxygen consumed in 5 days by biological processes breaking down 

organic waste. 

Blowdown 

The discharge of water with high concentrations of accumulated solids from boilers to prevent 

plugging of the boiler tubes or steam lines. In cooling towers, blowdown is discharged to reduce the 

concentration of dissolved salts in the recirculating cooling water. 

Bypass [40 CFR 403.17(a)] 

The intentional diversion of wastestreams from any portion of an industrial user’s treatment facility. 

Categorical Industrial User (CIU) 

An industrial user subject to national categorical pretreatment standards.

Categorical pretreatment standards [paraphrased from 40 CFR 403.6]

Standards specifying the quantity, concentration, or pollutant properties of pollutants that may be 

discharged to POTWs. EPA promulgates pretreatment standards for specific industry categories in 

accordance with CWA section 307. These standards are codified in 40 CFR chapter I, subchapter N, 

Parts 405–471. 

Chronic effect 

An adverse effect on a human or animal in which symptoms recur frequently or develop slowly over a 

long period. 

Chronic exposure 

Multiple exposures occurring over an extended period or over a significant fraction of an animal's or 

human's lifetime (usually 7 years to a lifetime). 

Chronic toxicity 

The capacity of a substance to cause long-term poisonous health effects in humans, animals, fish, and 

other organisms. 

Clean Water Act (CWA) 

The common name for the Federal Water Pollution Control Act. Public Law 92-500; 33 U.S.C. 

section 1251 et seq.; the statutory authority for both the NPDES Permit Program and the National 

Pretreatment Program. 

Code of Federal Regulations (CFR) 

A codification of federal rules published annually by the Office of the Federal Register National 

Archives and Records Administration. Title 40 of the CFR contains the regulations for “Protection of 

the Environment.” 

Combined Sewer Overflow (CSO) 

A discharge of untreated wastewater from a combined sewer system at a point before the headworks 

of a POTW. Because combined systems receive both storm event drainage (from rainfall or 

snowmelt, and street runoff) and untreated sewage, CSOs generally occur during wet weather when 

viii Introduction to the National Pretreatment Program 
Glossary 

the systems can become overloaded, resulting in bypassing of the treatment works and discharge 

directly to receiving waters. 

Combined Wastestream Formula (CWF) [paraphrased from 40 CFR 403.6(e)] 

Procedure for calculating alternative discharge limits at industrial facilities where a wastestream 

regulated by a categorical pretreatment standard is combined before treatment with wastestreams 

other than those subject to the standard. 

Compliance schedule 

A schedule of remedial measures included in a permit or an enforcement order, including a sequence 

of requirements (for example, actions, operations, or milestone events) that lead to compliance with 

the CWA and regulations. 

Composite sample 

A series of water samples taken over a given period of time and weighted by flow rate.

Concentration-based limit 

A limit based on the relative strength of a pollutant in a wastestream, usually expressed in milligrams 

per liter (mg/L). 

Continuous discharge 

A discharge that occurs without interruption during the operating hours of a facility, except for 

infrequent shutdowns for maintenance, process changes, or similar activities.

Control Authority [paraphrased from 40 CFR 403.3(f)] 

The POTW, in the case of a POTW with an approved pretreatment program, or the Approval 

Authority, in the case of a POTW without an approved pretreatment program. 

Conventional pollutants [40 CFR 401.16] 

Pollutants typical of municipal sewage, and for which municipal secondary treatment plants are 

typically designed. EPA has, pursuant to section 304(a) of the CWA, identified BOD5, total 

suspended solids (TSS), fecal coliform bacteria, oil and grease, and pH as conventional pollutants. 

Daily maximum limitation 

The maximum allowable discharge of pollutants during a 24-hour period. Where daily maximum 

limitations are expressed in units of mass, the daily discharge is the total mass discharged over the 

course of the day. Where daily maximum limitations are expressed in terms of a concentration, the 

daily discharge is the arithmetic average measurement of the pollutant concentration derived from all 

measurements taken that day.

Detection limit 

The minimum concentration of an analyte (substance) that can be measured and reported with 99 

percent confidence that the analyte concentration is greater than zero as determined by the procedure 

set forth in 40 CFR Part 136, appendix B. 

Development document 

A document that EPA prepares while developing effluent limitations guidelines and pretreatment 

standards. It explains the data and methodology used to establish effluent limitations and categorical 

pretreatment standards for an industrial category. 

Dilute wastestream [paraphrased from 40 CFR 403.6(e)(1)(i)] 

Used in calculating alternative standards for purposes of the combined wastestream formula, this 

wastestream is composed of the average daily flow (at least a 30-day average) from the following: (a) 

Introduction to the National Pretreatment Program ix 
Glossary 

boiler blowdown streams, noncontact cooling streams, stormwater streams, and demineralized 

backwash streams; provided, however, that where such streams contain a significant amount of a 

pollutant, and the combination of such streams, before treatment, with an industrial user's (IU’s) 

regulated process wastestream(s) will result in a substantial reduction of the concentration of that 

pollutant, the Control Authority, upon application of the IU, may exercise its discretion to determine 

whether such stream(s) should be classified as diluted or unregulated. In its application to the Control 

Authority, the IU must provide engineering, production, sampling and analysis, and such other 

information so the Control Authority can make its determination; or (b) sanitary wastestreams where 

such streams are not regulated by a categorical pretreatment standard; or (c) any process wastestreams 

that were, or could have been, entirely exempted from categorical pretreatment standards pursuant to 

paragraph 8 of the NRDC v. Costle consent decree (12 ERC 1833) for one or more of the following 

reasons (see 40 CFR Part 403, appendix D): 

 The pollutants of concern are not detectable in the effluent from the IU [paragraph 

(8)(a)(iii)]. 

 The pollutants of concern are present only in trace amounts and are neither causing nor 

likely to cause toxic effects [paragraph (8)(a)(iii)]. 

 The pollutants of concern are present in amounts too small to be effectively reduced by 

technologies known to the Administrator [paragraph (8)(a)(iii)]. 

 The wastestream contains only pollutants that are compatible with the POTW [paragraph 

(8)(b)(I)]. 

Direct discharger 

A point source that discharges a pollutant(s) to waters of the United States, such as streams, lakes, or 

oceans. These sources are subject to the National Pollutant Discharge Elimination System program 

regulations. Municipal and industrial facilities that introduce pollution through a defined conveyance 

or system such as outlet pipes are direct dischargers. 

Effluent Limitations Guideline (ELG) 

Any effluent limitations regulation issued by EPA pursuant to CWA section 304(b). These 

regulations are published to adopt or revise a national standard prescribing restrictions on quantities, 

rates, and concentrations of chemical, physical, biological, and other constituents that are discharged 

from point sources, in specific industrial categories (e.g., metal finishing, metal molding and casting). 

ELGs are sometimes referred to as effluent guidelines. 

Enforcement Response Plan (ERP) [paraphrased from 40 CFR 403.8(f)(5)] 

One of the key components of an approved POTW pretreatment program; includes step-by-step 

enforcement procedures developed and followed by POTW personnel to identify, document, and 

respond to violations by IUs. 

Existing source 

Any source of discharge, the construction or operation of which commenced before the publication by 

EPA of proposed categorical pretreatment standards that will be applicable to such source if the 

standard is thereafter promulgated in accordance with CWA section 307. 

Federal Water Pollution Control Act (FWPCA) 

The title of Public Law 92-500; 33 U.S.C. section 1251 et seq., also known as the Clean Water Act 

(CWA), enacted October 18, 1972. 

x Introduction to the National Pretreatment Program 
Glossary 

Flow-proportional composite sample 

A sample consisting of a series of aliquots (equal portions of the sample) in which each aliquot is 

collected after the passage of a defined volume of discharge. 

Flow-Weighted Average Formula (FWA) [paraphrased from 51FR21461] 

A procedure used to calculate alternative limits where wastestreams regulated by a categorical 

pretreatment standard and nonregulated wastestreams combine after treatment but before the 

monitoring point. 

Fundamentally Different Factors (FDF) [paraphrased from 40 CFR 403.13] 

Case-by-case variance from categorical pretreatment standards where the conditions at a specific IU 

are fundamentally different from the factors considered by EPA in developing the applicable 

category/subcategory standard. 

General prohibitions [40 CFR 403.5(a)(1)] 

Prohibitions that apply to each IU introducing pollutants into a POTW whether or not the IU is 

subject to other national pretreatment standards or any national, state, or local pretreatment 

requirements: 

 No IU may introduce into a POTW any pollutant(s) that cause pass through or 

interference. 

 An IU may have an affirmative defense in any action brought against it alleging a violation 

of the general or specific prohibitions where the IU can demonstrate that: 

– It did not know or have reason to know that its discharge, alone or in conjunction with a 

discharge or discharges from other sources, would cause pass through or interference; 

and 

– A local limit designed to prevent pass through or interference (or both) was developed for 

each pollutant in the IU's discharge that caused pass through or interference, and the IU 

was in compliance with each such local limit directly before and during the pass through 

or interference; or 

– If a local limit designed to prevent pass through or interference or both has not been 

developed for the pollutant(s) that caused the pass through or interference, the IU's 

discharge directly before and during the pass through or interference did not change 

substantially in nature or constituents from the IU's prior discharge activity when the 

POTW was regularly in compliance with the POTW's NPDES permit requirements and, 

in the case of interference, applicable requirements for sewage sludge use or disposal. 

Grab sample 

A sample that is taken from a wastestream on a one-time basis with no regard to the flow of the 

wastestream. A single grab sample should be taken over a period not to exceed 15 minutes. 

Headworks 

The point at which wastewater enters a wastewater treatment plant. The headworks may consist of bar 

screens, comminuters, a wet well, or pumps. 

Indirect discharge or discharge [40 CFR 403.3(i)] 

The introduction of pollutants into a POTW from any nondomestic source regulated under CWA 

section 307(b), (c), or (d). 

Industrial user (IU) or user [40 CFR 403.3(j)] 

A source of indirect discharge. 

Introduction to the National Pretreatment Program xi 
Glossary 

Industrial Waste Survey (IWS) 

The process of identifying and locating IUs and characterizing their industrial discharge. 

Inhibition 

Event that occurs when pollutant levels in a POTW’s wastewater or sludge cause operational 

problems for biological treatment processes involving secondary or tertiary wastewater treatment and 

alter the POTW’s ability to adequately remove BOD, TSS, and other pollutants. 

Injunction 

An order to a party to affirmatively perform, or to refrain from performing, some designated action. 

The federal environmental laws also empower EPA to issue administrative orders that require a 

regulated entity to perform, or refrain from performing, some designated action, and to come into, and 

maintain, compliance with those environmental laws. 

Injunctive relief 

Generally, action ordered of a defendant by a federal district court judge. This relief may be ordered 

either as a term of an order consented to by the parties in a lawsuit (where the parties file a "consent 

decree") or after a contested trial before the judge.

Interference [paraphrased from 40 CFR 403.3(k)]

A discharge that, alone or in conjunction with a discharge or discharges from other sources, both 

(1) inhibits or disrupts the POTW, its treatment processes or operations, or its sludge processes, use, 

or disposal; and (2) therefore is a cause of a violation of any requirement of the POTW's NPDES 

permit (including an increase in the magnitude or duration of a violation) or of the prevention of 

sewage sludge use or disposal in compliance with ... [applicable] statutory provisions and regulations 

or permits issued thereunder (or more stringent state or local regulations). 

Local limits [40 CFR 403.5(c)] 

Specific discharge limits developed and enforced by POTWs upon industrial or commercial facilities 

(IUs) to implement the general and specific discharge prohibitions listed in 40 CFR 403.5(a)(1) 

and (b). 

Maximum Allowable Headworks Loading (MAHL) 

The estimated maximum loading of a pollutant that can be received at a POTW’s headworks without 

causing pass through or interference. The most protective (lowest) of the allowable headworks 

loadings (see definition) estimated for a pollutant. 

Maximum Allowable Industrial Loading (MAIL) 

The estimated maximum loading of a pollutant that can be received at a POTW’s headworks from all 

permitted IUs and other controlled sources without causing pass through or interference. The MAIL is 

usually calculated by applying a safety factor to the MAHL and discounting for uncontrolled sources, 

hauled waste, and growth allowance. 

Middle-Tier Categorical Industrial User (MTCIU) [40 CFR 403.12(e)(3)(i)-(iii)] 

A classification that a Control Authority may apply to certain IUs, if their discharge of categorical 

wastewater does not exceed any of the following: 

 10.01 percent of the design dry-weather hydraulic capacity of the POTW, or 5,000 gallons 

per day (gpd), whichever is smaller, as measured by a continuous effluent flow monitoring 

device unless the IU discharges in batches 

 0.01 percent of the design dry-weather organic treatment capacity of the POTW 

xii Introduction to the National Pretreatment Program 
Glossary 

 30.01 percent of the MAHL for any pollutant for which approved local limits were 

developed by a POTW. 

The CA must also demonstrate that the CIU has not been in significant noncompliance for any time in 

the past two years, and that the CIU does not have daily flow rates, production levels, or pollutant 

levels that vary so significantly that decreasing the reporting requirement for the IU would result in 

data that are not representative of conditions occurring during the reporting period. 

Monthly average 

The arithmetic average value of all daily results for a calendar month for an individual pollutant 

parameter. Historically, EPA has considered a 30-day average to mean a monthly average. 

National Pollutant Discharge Elimination System (NPDES) 

The national program for issuing, modifying, revoking, and reissuing, terminating, monitoring, and 

enforcing discharge permits from point sources to waters of the United States, and imposing and 

enforcing pretreatment requirements, under CWA sections 307, 402, 318, and 405. 

National pretreatment standard or pretreatment standard or standard [40 CFR 403.3(l)] 

Any regulation containing pollutant discharge limits promulgated by EPA in accordance with CWA 

section 307(b) and (c) that applies to IUs. This term includes prohibitive discharge limits established 

pursuant to 40 CFR 403.5. 

New source [40 CFR 403.3(m)] 

Any building, structure, facility or installation from which there is or could be a discharge of 

pollutants, the construction of which began after the publication of proposed pretreatment standards 

under CWA section 307(c) that will be applicable to such source if such standards are thereafter 

promulgated in accordance with that section provided that any of the following are true: 

 The building, structure, facility or installation is constructed at a site at which no other 

discharge source is located. 

 The building, structure, facility, or installation totally replaces the process or production 

equipment that causes the discharge of pollutants at an existing source. 

 The production or wastewater generating processes of the building, structure, facility, or 

installation are substantially independent of an existing source at the same site. In 

determining whether these are substantially independent, factors such as the extent to 

which the new facility is integrated with the existing plant, and the extent to which the new 

facility is engaged in the same general type of activity as the existing source should be 

considered. 

 Construction on a site at which an existing source is located results in a modification rather 

than a new source if the construction does not create a new building, structure, facility, or 

installation meeting the criteria of paragraphs (m)(1)(ii), or (m)(1)(iii) of this section but 

otherwise alters, replaces, or adds to existing process or production equipment. 

 Construction of a new source, as defined under this paragraph, has commenced if the 

owner or operator has begun, or caused to begin as part of a continuous onsite construction 

program: 

 Any placement, assembly, or installation of facilities or equipment; or 

Introduction to the National Pretreatment Program xiii 
Glossary 

 Significant site preparation work including clearing, excavation, or removal of existing 

buildings, structures, or facilities that is necessary for the placement, assembly, or 

installation of new source facilities or equipment; or 

 Entered into a binding contractual obligation for the purchase of facilities or equipment 

that are intended to be used in its operation within a reasonable time. Options to purchase 

or contracts that can be terminated or modified without substantial loss, and contracts for 

feasibility, engineering, and design studies do not constitute a contractual obligation under 

this paragraph. 

Ninety-day final compliance report [paraphrased from 40 CFR 403.12(d)] 

A report submitted by CIUs within 90 days following the date for final compliance with applicable 

categorical standards. The report must contain flow measurement (of regulated process streams and 

other streams), measurement of pollutants, and a certification as to whether the categorical standards 

are being met. 

Nonconventional pollutant 

Any pollutant that is neither a toxic pollutant nor a conventional pollutant (e.g., manganese, 

ammonia).

Noncontact cooling water 

Water used for cooling that does not come into direct contact with any raw material, intermediate 

product, waste product, or finished product. The only pollutant contributed from the discharge is heat. 

Non-regulated wastestream

Unregulated and dilute wastestreams (not regulated by categorical standards). 

Nonsignificant Categorical Industrial User (NSCIU) [40 CFR 403.3(v)(2)] 

An IU subject to categorical pretreatment standards under 40 CFR 403.6 and 40 CFR chapter I, 

subchapter N, that the POTW has determined is exempt from the definition of SIU on a finding that 

the IU never discharges more than 100 gpd of total categorical wastewater (excluding sanitary, 

noncontact cooling and boiler blowdown wastewater, unless specifically included in the pretreatment 

standard). The IU must also meet the following conditions: 

 The IU, before the POTW’s finding, has consistently complied with all applicable 

categorical pretreatment standards and requirements. 

 The IU annually submits the certification statement required in 40 CFR 403.12(q) together 

with any additional information necessary to support the certification statement. 

 The IU never discharges any untreated concentrated wastewater. 

North American Industry Classification System (NAICS) 

A system developed by the U.S. Office of Management and Budget (in cooperation with Statistics 

Canada and Mexico's Instituto Nacional de Estadística, Geografía e Informática) that is used to 

classify business establishments. NAICS replaced the Standard Industrial Classification (SIC) system 

in 1998. 

Pass through [40 CFR 403.3(p)] 

A discharge that exits the POTW into waters of the United States in quantities or concentrations that, 

alone or in conjunction with a discharge or discharges from other sources, is a cause of a violation of 

any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of 

a violation). 

xiv Introduction to the National Pretreatment Program 
Glossary 

Periodic compliance report [paraphrased from 40 CFR 403.12(e) & (h)] 

A report on compliance status submitted by CIUs and significant non-CIUs to the POTW at least 

semiannually (once every 6 months). For middle-tier categorical industrial users, the POTW may 

reduce the requirement to report to no less frequently than once a year, unless required more 

frequently in the pretreatment standard or by the Approval Authority. A facility determined to be an 

NSCIU must annually submit a certification statement in addition to any other alternative report 

required by the POTW.

Point source [40 CFR 122.2] 

Any discernible, confined, and discrete conveyance, including any pipe, ditch, channel, tunnel, 

conduit, well, discrete fixture, container, rolling stock, concentrated animal feeding operation, landfill 

leachate collection system, vessel or other floating craft from which pollutants are or could be 

discharged. 

Pollutant [40 CFR 122.2] 

Dredged spoil; solid waste; incinerator residue; filter backwash; sewage; garbage; sewage sludge; 

munitions; chemical wastes; biological materials; radioactive materials (except those regulated under 

the Atomic Energy Act of 1954, as amended [42 U.S.C. section 2011 et seq.]); heat; wrecked or 

discarded equipment; rock; sand; cellar dirt; and industrial, municipal, and agricultural waste 

discharged into water. 

Pretreatment [paraphrased from 40 CFR 403.3(s)] 

The reduction of the amount of pollutants, the elimination of pollutants, or the alteration of the nature 

of pollutant properties in wastewater before or in lieu of discharging, or otherwise introducing, such 

pollutants into a POTW. 

Pretreatment requirements [40 CFR 403.3(t)]

Any substantive or procedural requirement related to pretreatment, other than a national pretreatment 

standard, imposed on an IU. 

Pretreatment Standards for Existing Sources (PSES) 

Categorical standards and requirements applicable to industrial sources that began construction before 

the publication of the proposed pretreatment standards for that industrial category (see individual 

standards at 40 CFR Parts 405–471) or on a date specifically provided in promulgation of the 

pretreatment standard. 

Pretreatment Standards for New Sources (PSNS) 

Categorical standards and requirements applicable to industrial sources that began construction after 

the publication of the proposed pretreatment standards for that industrial category (see individual 

standards at 40 CFR Parts 405–471) or on a date specifically provided in promulgation of the 

pretreatment standard. 

Process wastewater 

Any water that, during manufacturing or processing, comes into contact with or results from the 

production or use of any raw material, intermediate product, finished product, byproduct, or waste 

product. 

Production-based standards 

A discharge standard expressed in terms of pollutant mass allowed in a discharge per unit of product 

manufactured. For example, 40 CFR Part 467, Aluminum Forming, standards are in milligrams per 

kilograms of work piece removed during production. Other production-based categories express 

limits in milligrams per kilograms of material processed. 

Introduction to the National Pretreatment Program xv 
Glossary 

Publicly Owned Treatment Works (POTW) [40 CFR 403.3(q)] 

A treatment works (as defined by CWA section 212) that is owned by a state or municipality [as 

defined by CWA section 502(4)]. This definition includes any devices or systems used in the storage, 

treatment, recycling, and reclamation of municipal sewage or industrial wastes of a liquid nature. It 

also includes sewers, pipes, or other conveyances only if they convey wastewater to a POTW 

treatment plant. The term also means the municipality [as defined in CWA section 502(4)] that has 

jurisdiction over the indirect discharges to and the discharges from such a treatment works. 

Regulated wastestream 

For purposes of applying the combined wastestream formula, a wastestream from an industrial 

process that is regulated by a categorical standard. 

Removal credit [paraphrased from 40 CFR 403.7] 

Variance for an IU from the otherwise applicable categorical pretreatment standard that reflects the 

POTW’s removal of that pollutant. 

Representative sample 

A sample from a wastestream that is as nearly identical as possible in composition to that in the larger 

volume of wastewater being discharged and is typical of the discharge from the facility on a normal 

operating day. 

Sanitary Sewer Overflow (SSO) 

Untreated or partially treated sewage overflows from a sanitary sewer collection system. 

Self-monitoring 

Sampling and analyses performed by a facility to measure compliance with a permit or other 

regulatory requirements. 

Sewage sludge [40 CFR 122.2] 

Any solid, semisolid, or liquid residue removed during the treatment of municipal wastewater or 

domestic sewage. Sewage sludge includes solids removed during primary, secondary, or advanced 

wastewater treatment, scum, septage, portable toilet pumpings, type III marine sanitation device 

pumpings (33 CFR part 159), and sewage sludge products. Sewage sludge does not include grit or 

screenings, or ash generated during the incineration of sewage sludge. Also referred to as biosolids. 

Sewer Use Ordinance (SUO) 

A legal mechanism implemented by a local government entity that establishes requirements for the 

discharge of pollutants into a POTW. 

Significant Industrial User (SIU) [40 CFR 403.3(v)] 

(1) All users subject to categorical pretreatment standards under 40 CFR 403.6 and 40 CFR chapter I, 

subchapter N, except those designated as NSCIUs (see definition above); and (2) any other IU that 

discharges an average of 25,000 gpd or more of process wastewater to the POTW (excluding sanitary, 

noncontact cooling, and boiler blowdown wastewater); contributes a process wastestream that makes 

up 5 percent or more of the average dry-weather hydraulic or organic capacity of the POTW 

treatment plant; or is designated as such by the POTW on the basis that the IU has a reasonable 

potential for adversely affecting the POTW’s operation or for violating any pretreatment standard or 

requirement [in accordance with 40 CFR 403.8(f)(6)]. 

Significant Noncompliance (SNC) [40 CFR 403.8(f)(2)(viii)] 

IU violations that meet one or more of the following criteria: 

xvi Introduction to the National Pretreatment Program 
Glossary 

Introduction to the National Pretreatment Program xvii 

 Chronic violations of wastewater discharge limits, defined here as those in which 66 

percent or more of all the measurements for each pollutant parameter taken during a 6-

month period exceed (by any magnitude) a numeric pretreatment standard or requirement, 

including instantaneous limits, as defined by 40 CFR 403.3(l) 

 Technical Review Criteria (TRC) violations, defined here as those in which 33 percent or 

more of all the measurements for each pollutant parameter taken during a 6-month period 

equal or exceed the product of the numeric pretreatment standard or requirement including 

instantaneous limits, as defined by 40 CFR 403.3(l) multiplied by the applicable TRC 

(TRC = 1.4 for BOD, TSS, fats, oil, and grease and 1.2 for all other pollutants except pH) 

 Any other violation of a pretreatment standard or requirement as defined by 40 CFR 

403.3(l) (daily maximum, long-term average, instantaneous limit, or narrative standard) 

that the POTW determines has caused, alone or in combination with other dischargers, 

interference or pass through (including endangering the health of POTW personnel or the 

general public) 

 Any discharge of a pollutant that has caused imminent endangerment to human health, 

welfare, or to the environment or has resulted in the POTW’s exercise of its emergency 

authority under paragraph (f)(1)(vi)(B) of 40 CFR 403.8 to halt or prevent such a discharge 

 Failure to meet, within 90 days after the schedule date, a compliance schedule milestone 

contained in a local control mechanism or enforcement order for starting construction, 

completing construction, or attaining final compliance 

 Failure to provide, within 45 days2

 after the due date, required reports such as baseline 

monitoring reports, 90-day compliance reports, periodic self-monitoring reports, and 

reports on compliance with compliance schedules 

 Failure to accurately report noncompliance 

 Any other violation or group of violations, which can include a violation of best 

management practices, that the POTW determines will adversely affect the operation or 

implementation of the local pretreatment program. 

Slug discharge [40 CFR 403.8(f)(2)(vi)] 

Any discharge of a nonroutine, episodic nature, including an accidental spill or a noncustomary batch 

discharge that has a reasonable potential to cause interference or pass through, or in any other way 

violate the POTW’s regulations, local limits, or permit conditions. 

Specific prohibitions [40 CFR 403.5(b)] 

Prohibitions that apply to each IU introducing pollutants into a POTW regardless of whether the IU is 

subject to other national pretreatment standards or any national, state, or local pretreatment 

requirements. The following pollutants must not be introduced into a POTW: 

 Pollutants that create a fire or explosion hazard in the POTW, including wastestreams with 

a closed cup flashpoint of less than 140 degrees Fahrenheit (°F) or 60 degrees Celcius (°C) 

using the test methods specified in 40 CFR 261.21 

 Pollutants that will cause corrosive structural damage to the POTW, but in no case 

discharges with pH lower than 5.0, unless the POTW is specifically designed to 

accommodate such discharges 

 

2

 The Streamlining Rule changed the timeframe to 45 days. Many POTWs have elected to maintain the previous, more 

stringent requirement that reports submitted more than 30 days late are considered to be in significant noncompliance. 
Glossary 

 Solid or viscous pollutants in amounts that will cause obstruction to the flow in the POTW 

resulting in interference 

 Any pollutant, including oxygen-demanding pollutants (BOD and the like) released in a 

discharge at a flow rate or concentration that will cause interference with the POTW 

 Heat in amounts that will inhibit biological activity in the POTW resulting in interference, 

but in no case heat in such quantities that the temperature at the POTW treatment plant 

exceeds 104 °F (40 °C) unless the Approval Authority, at the POTW’s request, approves 

alternative temperature limits 

 Petroleum oil, nonbiodegradable cutting oil, or products of mineral oil origin in amounts 

that will cause interference or pass through 

 Pollutants that result in the presence of toxic gases, vapors, or fumes within the POTW in a 

quantity that could cause acute worker health and safety problems 

 Any trucked or hauled pollutants, except at discharge points designated by the POTW. 

Standard Industrial Classification (SIC) 

A system developed by the U.S. Office of Management and Budget that is used to classify various 

types of business entities. In 1998 the North American Industry Classification System (NAICS) 

replaced the SIC. 

Stormwater 

Rainwater, snowmelt, and surface runoff and drainage. 

Time-proportional composite sample 

A sample consisting of a series of aliquots collected after the passage of a definite period, regardless 

of the volume or variability of the rate of flow during that period. 

Toxic pollutant 

Pollutant listed by the EPA Administrator under CWA section 307(a). The list of the current 126

toxic pollutants can be found at http://water.epa.gov/scitech/methods/cwa/pollutants.cfm. 

Toxicity Reduction Evaluation (TRE) 

A site-specific study conducted in a stepwise process designed to identify the causative agent(s) of 

effluent toxicity, isolate the sources of toxicity, evaluate the effectiveness of toxicity control options, 

and then confirm the reduction in effluent toxicity. 

Toxicity test 

A procedure to determine the toxicity of a chemical or an effluent using living organisms. A toxicity 

test measures the degree of effect on exposed test organisms from a specific chemical or effluent.

Unregulated wastestream 

For purposes of applying the combined wastestream formula, a wastestream not regulated by a 

categorical standard and not considered a dilute wastestream. 

Upset [40 CFR 403.16(a)] 

An exceptional incident in which there is unintentional and temporary noncompliance with 

categorical pretreatment standards because of factors beyond the reasonable control of the IU. An 

upset does not include noncompliance to the extent caused by operational error, improperly designed 

treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or 

improper operation.

xviii Introduction to the National Pretreatment Program 
Glossary 

Introduction to the National Pretreatment Program xix 

Water quality criteria

Elements of state water quality standards, expressed as constituent concentrations, levels, or narrative 

statements, representing a quality of water that supports a particular use. When criteria are met, water 

quality will generally protect the designated use. 

Water Quality Standard (WQS) 

Provisions of state or federal law that consist of a designated use or uses for the waters of the United 

States and water quality criteria for such waters based upon such uses. Water quality standards are to 

protect the public health or welfare, enhance the quality of water, and serve the purposes of the Clean 

Water Act. 

Whole Effluent Toxicity (WET)

The aggregate toxic effect of an effluent measured directly by a toxicity test. 
Chapter 1. POTWS and the Need for the Pretreatment Program 

Introduction to the National Pretreatment Program 1-1 

CHAPTER 1. 

POTWS AND THE NEED FOR THE 

PRETREATMENT PROGRAM

SEWAGE TREATMENT

Publicly owned treatment works (POTWs) collect wastewater from homes, commercial buildings, 

and industrial facilities and transport it via a series of pipes, known as a collection system, to the 

treatment plant(s). Collection systems can flow entirely by gravity or can include lift stations, which 

pump the wastewater via a force main to a higher elevation from which the wastewater can then continue 

by gravity. Ultimately, the collection system delivers this sewage to the treatment plant. The treatment 

plant then removes harmful organisms and other contaminants from the sewage so the wastewater can be 

discharged safely into a receiving stream. Without treatment, sewage creates bad odors; contaminates 

rivers, lakes, and water supplies; and spreads disease. There are more than 16,000 sewage treatment 

plants in the United States treating more than 32 billion gallons per day of wastewater.3

 There are 

approximately 1,600 POTWs that have approved pretreatment programs, and there are 20,630 significant 

industrial users (SIUs) discharging to those POTWs. Many of the POTWs manage more than one sewage 

treatment plant. Some states and EPA Regions oversee indirect discharging SIUs rather than requiring the 

POTW to develop a pretreatment program. The number of indirect discharging SIUs that EPA and states 

oversee directly is 2,197. Therefore, a total of 22,827 SIUs are discharging to sewage treatment plants in 

the United States.4

Generally, POTWs are designed to treat only domestic sewage. The typical POTW treatment 

process consists of primary and secondary treatment, disinfection (to kill any remaining pathogens), and 

some form of solids handling. Primary treatment is designed to remove large solids (e.g., rags and debris) 

and smaller inorganic grit. Typical primary treatment operations include screening and settling. 

Secondary treatment removes organic contaminants by using microorganisms to consume biodegradable 

organics. Activated sludge, trickling filters, and rotating biological contactors are examples of common 

secondary treatment operations. Depending on effluent discharge requirements, POTWs can perform 

advanced treatment operations, such as nitrification (to convert ammonia and nitrite to the less-toxic 

nitrate form of nitrogen), denitrification (to convert nitrate to molecular nitrogen), and physical-chemical 

treatment (to remove dissolved metals and organics). After treatment is complete, effluent is discharged to 

a receiving stream, typically a creek, river, lake, estuary, or ocean. Some POTWs might apply treated 

 

3

 U.S. Environmental Protection Agency, Clean Water Needs Survey 2008 Report to Congress (2008). 4

 Permit Compliance System and Integrated Compliance Information System data reported by EPA regions for 2010. 

Chapter 1. Applicable EPA References 

Environmental Regulations and Technology: The National Pretreatment Program (EPA/625/10-86/005) 

EPA's National Pretreatment Program, 1973-2003: Thirty Years of Protecting the Environment 

(EPA 833-F-03-001) 

National Pretreatment Program: Report to Congress (EPA 21W-4004) 

Report to Congress on the Discharge of Hazardous Wastes to POTWs (EPA 530-SW-86-004) 
Chapter 1. POTWS and the Need for the Pretreatment Program 

effluent directly to golf courses, parkland, or croplands. Industrial users (IUs) are increasingly 

implementing measures to reuse effluent. For example, effluent can be used as makeup water in cooling 

towers and boilers. 

Both primary and secondary treatment processes generate waste solids, known as sewage sludge 

or biosolids. Sludge from the treatment process can be used as fertilizer or soil conditioner, disposed of in 

a landfill, or incinerated in a sewage sludge incinerator with the ash disposed of in a landfill. 

As described earlier, POTWs are designed to treat 

typical household waste, biodegradable commercial waste, 

and biodegradable industrial waste. The regulations at Title 

40 of the Code of Federal Regulations (CFR), section 401.16, 

define five contaminants as conventional pollutants. These 

conventional pollutants, identified in figure 1-1, include the 

specific pollutants that are expected to be present in domestic 

discharges to POTWs. Commercial and industrial facilities 

may, however, discharge toxic or non-conventional pollutants

that the treatment plant is neither designed for nor able to remove. 

Biochemical Oxygen Demand (BOD) 

Total Suspended Solids (TSS) 

Fecal Coliform 

pH 

Oil and Grease (O&G) 

Figure 1-1. Conventional pollutants. 

NEED FOR THE PRETREATMENT PROGRAM

As noted earlier, POTWs are not designed to treat most toxic or non-conventional pollutants that 

are present in industrial waste. Consequently, discharges from both industrial and commercial sources can 

cause problems at POTWs and can have detrimental effects on the water quality of the receiving 

waterbody. The undesirable effects of those discharges can be prevented by using treatment techniques or 

management practices to reduce or eliminate the discharge of the contaminants. The act of treating 

wastewater before discharge to a POTW is commonly referred to as pretreatment. The National 

Pretreatment Program, published in 40 CFR Part 403, provides the regulatory basis to require 

nondomestic dischargers to comply with pretreatment standards to ensure that the goals of the Clean 

Water Act (CWA) are attained. The objectives of the National Pretreatment Program are stated in 40 CFR 

403.2, as follows: 

 Prevent the introduction of pollutants into a POTW that will interfere with the operation of 

the POTW, including interference with its use or disposal of municipal sludge 

 Prevent the introduction of pollutants into a POTW that will pass through the treatment 

works or otherwise be incompatible with such works 

 Improve opportunities to recycle and reclaim municipal and industrial wastewaters and 

sludges. 

The two key terms used in EPA’s objectives for the National Pretreatment Program, interference

and pass through, are defined in 40 CFR 403.3(k) and (p): 

Interference: A discharge which, alone or in conjunction with a discharge or discharges from 

other sources, both: 

 Inhibits or disrupts the POTW, its treatment processes or operations, or its sludge 

processes, use or disposal, and 

 Therefore is a cause of a violation of any requirement of the POTW’s NPDES permit 

(including an increase in the magnitude or duration of a violation) or of the prevention of 

sewage sludge use or disposal in compliance with the following statutory provisions and 

regulations or permits issued thereunder (or more stringent state or local regulations): 

1-2 Introduction to the National Pretreatment Program 
Chapter 1. POTWS and the Need for the Pretreatment Program 

CWA section 405; the Solid Waste Disposal Act (including the Resource Conservation 

and Recovery Act and state regulations contained in any state sludge management plan 

prepared pursuant to subtitle D of the Solid Waste Disposal Act); the Clean Air Act; the 

Toxic Substances Control Act; and the Marine Protection, Research and Sanctuaries Act. 

Pass Through: A discharge that exits the POTW into waters of the United States in quantities or 

concentrations which, alone or in conjunction with a discharge or discharges from other sources, 

is a cause of a violation of any requirement of the POTW’s NPDES permit (including an increase 

in the magnitude or duration of a violation). 

As outlined in EPA’s objectives, toxic pollutants can pass through the treatment plant into the 

receiving stream, posing serious threats to aquatic life, human recreation, and those consuming fish and 

shellfish from the waters. Pass through can make waters unswimmable or unfishable, in direct opposition 

to the goals of the CWA. It can also interfere with the biological activity of the treatment plant, causing 

discharges of untreated or inadequately treated sewage. 

Even where the POTW has the capability to remove the toxic pollutants, the toxic pollutants can 

end up in the sewage sludge, thereby limiting sludge disposal options or increasing the cost of disposal. 

Incinerating contaminated sludge can release toxic emissions into the atmosphere. Toxic metals removed 

in primary treatment can affect the efficiency of sludge digestion, a process that uses bacteria to stabilize 

sludge solids. For example, chromium can inhibit reproduction of aerobic digestion microorganisms, 

thereby disrupting sludge treatment and producing sludge that must be disposed of with special treatment. 

Uncontaminated sludge, on the other hand, can be used as fertilizer or soil conditioner, thereby improving 

the productivity of land. Many municipalities apply treated sewage sludge to pastureland or parkland; that 

would not be an option if the sludge were contaminated. 

Gases or vapors from volatile organics discharged to sewer systems can accumulate in the head 

space of sewers, increasing the likelihood of explosions that could cause significant damage. Probably the 

most well-known adverse effect from industrial discharges to POTWs in the United States is the 

explosion in Louisville, Kentucky, that occurred in 1981. The explosion was a result of excessive 

discharges of hexane into the collection system. The hexane in the pipes eventually ignited and destroyed 

more than 3 miles of sewers and roadways, causing $20 million in damage. Discharge limitations and 

management practices to control slug discharges have significantly reduced the likelihood of future 

catastrophes like that explosion. 

Discharges of toxic organics can also result in the release of poisonous gas. That occurs most 

often when acidic wastes react with other wastes in the discharge. For example, cyanide and acid, both 

present in many electroplating operations, react to form highly toxic hydrogen cyanide gas. Similarly, 

sulfides from leather tanning can combine with acid to form hydrogen sulfide, another toxic gas. Such 

gases can be highly dangerous to POTW collection system operators as they perform their duties. Other 

problems associated with toxic discharges (summarized in figure 1-2) further document the urgency of 

keeping toxics out of collection systems and POTWs. 

 Corrosion of collection systems and treatment plants can be caused by acidic discharges or 

discharges containing elevated levels of sulfate (forming toxic and corrosive hydrogen sulfide). 

 Groundwater pollution can occur from leaks in the collection system or pollutants from 

contaminated sewage sludge. 

 Air pollution can occur from volatilization of toxic chemicals in the POTW collection system or 

treatment plant, or through incineration of sewage sludge. 

Figure 1-2. Other problems associated with toxic nondomestic discharges. 

Introduction to the National Pretreatment Program 1-3 
Chapter 1. POTWS and the Need for the Pretreatment Program 

1-4 Introduction to the National Pretreatment Program 

The National Pretreatment Program’s strategic partnerships go beyond ensuring the success of 

POTWs. Such partnerships promote the following: 

 Protecting drinking water supplies by reducing contaminants released into source waters 

by POTWs 

 Preventing overflows that include raw sewage from sewers through controls on oil and 

grease 

 Extending the life of the nation’s wastewater infrastructure through EPA’s Four Pillars of 

Sustainable Infrastructure Initiative. EPA believes that better management practices, 

efficient water use, full-cost pricing of water, and a watershed approach to environmental 

management can all help utilities to operate more sustainably now and in the long term. 

 Worker safety by protecting workers from harmful fumes through limits on discharging 

dangerous gases and gas-forming substances 

 Homeland security by ensuring proper disposal of waste from decontamination showers.5

The National Pretreatment Program is charged with controlling toxic, conventional, and nonconventional pollutants from nondomestic sources that discharge into sewer systems, as described in 

CWA section 307(a). The list of pollutants appears in the Code of Federal Regulations at 40 CFR 401.15. 

It is an important starting point for EPA to consider, for example, in developing national discharge 

standards (such as effluent guidelines) or in national permitting programs (such as NPDES). The list 

contains 65 entries; many entries, such as haloethers, are for groups of pollutants. 

The Priority Pollutant list makes the list of toxic pollutants more usable, in a practical way, for 

the purposes assigned to EPA by the CWA. For example, the Priority Pollutant list is more practical than 

the list of toxic pollutants for testing and for regulation in that chemicals are described by their individual 

chemical names. The list of toxic pollutants, in contrast, contains open-ended groups of pollutants, such 

as chlorinated benzenes. That group contains hundreds of compounds; there is no test for the group as a 

whole, nor is it practical to regulate or test for all the compounds. The Priority Pollutants are a set of 

chemical pollutants that EPA regulates and for which EPA has published analytical test methods. These 

pollutants fall into two categories: 

 Metals—including lead, mercury, chromium, and cadmium—cannot be destroyed or 

broken down through treatment or environmental degradation. Toxic metals can cause a 

number of human health problems, such as lead poisoning and cancer. In addition, the 

consumption of contaminated seafood and agricultural food crops can result in exposures 

exceeding recommended safe levels. 

 Toxic organics—including solvents, pesticides, dioxins, and polychlorinated biphenyls 

(PCBs) —can be cancer-causing and lead to other serious ailments, such as kidney and 

liver damage, anemia, and heart failure. In 2008 EPA’s Office of Science and Technology 

identified 4,249 waterbodies as having unsafe levels of toxic organics in fish and wildlife.6

The National Pretreatment Program also helps prevent excess loadings of the conventional 

pollutants biochemical oxygen demand (BOD), total suspended solids (TSS), fecal coliform bacteria, oil 

and grease, and pH. Although POTWs are designed to treat conventional pollutants, these pollutants have 

caused violations or operational problems at the POTWs. Many POTWs have ongoing problems with 

 

5

 U.S. Environmental Protection Agency, Office of Water, EPA’s National Pretreatment Program, 1973-2003: Thirty Years of 

Protecting the Environment, EPA 833-F-03-001 (2004). 6

 U.S. Environmental Protection Agency, Office of Science and Technology, National Listing of Fish Advisories, EPA 823-F09-007 (2008). http://www.epa.gov/waterscience/fish/advisories. 
Chapter 1. POTWS and the Need for the Pretreatment Program 

Introduction to the National Pretreatment Program 1-5 

excessive loadings of BOD and TSS from industrial and commercial sources causing pass through or 

interference and problems in the collection system. 

A nonconventional pollutant is any pollutant that is neither a toxic pollutant nor a conventional 

pollutant. In recent years, permitting agencies have sought to reduce the amount of nonconventional 

pollutants such as nutrients (e.g., ammonia, nitrogen, phosphorus) and other chemicals discharged from 

POTWs. Excess nutrients in surface waters can cause excessive algal growth, reduce dissolved oxygen, 

and impair aquatic life. Another example of nonconventional pollutants is molybdenum, which can be 

introduced to the wastestream from the use of corrosion inhibitors at IUs that add cooling water and boiler 

water corrosion control additives. Technology upgrades at POTWs have enabled additional nutrient and 

other nonconventional pollutant reductions. 

Reductions in pollutants discharged can ensure that industrial development vital to the economic 

well-being of a community is compatible with a healthy environment. As noted later, in chapter 2, a 

POTW is responsible for ensuring that discharges by industrial and commercial facilities that discharge 

into its collection system do not cause problems at the POTW or result in deleterious impacts on receiving 

stream water quality. In 1991 EPA estimated that 190 million to 204 million pounds of metals and 30 

million to 108 million pounds of organics were removed each year as a result of National Pretreatment 

Program requirements.7

 That is substantiated by many POTWs reporting significant reductions in the 

loadings of toxics to their treatment plants that are directly attributable to implementing the National 

Pretreatment Program. 

Section 304(a) of the CWA provides a list of priority pollutants for which EPA has established 

ambient water quality criteria (the basis of state water quality standards) and effluent limitations (rules 

controlling environmental releases from specific industrial categories that are based on the Best Available 

Technology Economically Achievable). 

The current list of 126 priority pollutants is available at 

http://water.epa.gov/scitech/methods/cwa/pollutants.cfm. 

 

7

 U.S. Environmental Protection Agency, National Pretreatment Program: Report to Congress, 1991 (1991). 
Chapter 2. Overview of the National Pretreatment Program 

CHAPTER 2. 

OVERVIEW OF THE NATIONAL 

PRETREATMENT PROGRAM

Guidance for Conducting a Pretreatment Compliance Inspection (EPA 300R92009) 

Guidance for Reporting and Evaluating POTW Noncompliance with Pretreatment Implementation Requirements

(EPA September 1987) 

Guidance Manual for POTW Pretreatment Program Development (EPA 833/B-83-100) 

Pretreatment Compliance Inspection and Audit Manual for Approval Authorities (EPA 833/B-86-100) 

Procedures Manual for Reviewing a POTW Pretreatment Program Submission (EPA 833/B-83-200) 

Chapter 2. Applicable EPA Guidance 

Control Authority Pretreatment Audit Checklist and Instructions (EPA 833-B-10-001) 

THE CLEAN WATER ACT

On October 18, 1972, the Federal Water Pollution Control Act Amendments of 1972 became law, 

declaring the restoration and maintenance of the chemical, physical, and biological integrity of the 

nation's water a national goal (figure 2-1). Although procedures for implementing the act (more 

commonly referred to as the Clean Water Act, or CWA) have been reevaluated and modified over time, 

the 1972 goal has remained unchanged throughout the act’s 39-year history. 

To restore and maintain the chemical, physical, and biological integrity of the nation’s waters: 

1. It is the national goal that the pollutants into the navigable waters be eliminated by 1985; 

2. It is the national goal that wherever attainable, an interim goal of water quality which provides for the protection and 

propagation of fish, shellfish, and wildlife and provides for recreation in and on the water be achieved by July 1, 1983; 

3. It is the national policy that the discharge of toxic pollutants in toxic amounts be prohibited; 

4. It is the national policy that federal financial assistance be provided to construct publicly owned waste treatment 

works; 

5. It is the national policy that areawide waste treatment management planning processes be developed and 

implemented to assure adequate control of sources of pollutants in each state; 

6. It is the national policy that a major research and demonstration effort be made to develop technology necessary to 

eliminate the discharge of pollutants into the navigable waters, waters of the contiguous zone, and the oceans; and 

7. It is the national policy that programs for the control of nonpoint sources of pollution be developed and implemented in 

an expeditious manner so as to enable the goals of this Chapter to be met through the control of both point and 

nonpoint sources of pollution. 

Figure 2-1. Section 101(a) of the CWA. 

The CWA established a water quality approach along with EPA-promulgated, industry-specific, 

technology-based effluent limitations. The NPDES permit program was established under the CWA to 

control the discharge of pollutants from point sources and served as a vehicle to implement the industrial 

technology-based standards for direct dischargers and to implement the categorical pretreatment standards 

for indirect dischargers under the POTW pretreatment program. To implement pretreatment standards and 

Introduction to the National Pretreatment Program 2-1 
Chapter 1. POTWS and the Need for the Pretreatment Program 

requirements, EPA promulgated 40 CFR Part 128 in late 1973, establishing general prohibitions against 

treatment plant interference and pass through and setting pretreatment standards for the discharge of 

incompatible pollutants from specific industrial categories. 

In 1975 several environmental groups filed suit against EPA, challenging the Agency’s criteria 

for identifying toxic pollutants, its failure to promulgate effluent standards, and its failure to promulgate 

pretreatment standards for numerous industrial categories. As a result of that litigation, EPA promulgated 

the General Pretreatment Regulations at 40 CFR Part 403 on June 26, 1978, replacing the 40 CFR Part 

128 requirements. Also as a result of the suit, EPA agreed to regulate the discharge of 65 categories of 

pollutants comprising the 126 priority pollutants from 21 industrial categories. The list of priority 

pollutants remains in effect today; the list of regulated industrial categories has grown to more than 50 

distinct industries. A discussion of industry-specific requirements is provided in chapter 3. 

THE GENERAL PRETREATMENT REGULATIONS

The General Pretreatment Regulations establish responsibilities among federal, state, and local 

government; industry; and the public to implement pretreatment standards to control pollutants that pass 

through or interfere with POTW treatment processes or that can contaminate sewage sludge. The 

regulations, which have been revised numerous times since originally published in 1978, consist of 20 

sections and seven appendices. The most recent revision of the General Pretreatment Regulations was 

promulgated under the pretreatment Streamlining Rule, which became effective in November 2005. (A 

copy of that rule is on EPA’s website at http://www.epa.gov/npdes/regulations/streamlining.pdf.) The 

Streamlining Rule addresses requirements for, and oversight of, IUs that introduce pollutants into 

POTWs, and it is different from other major amendments to the General Pretreatment Regulations in that 

it increased POTW flexibility in program implementation. In certain instances, that flexibility can allow 

for a reduction in minimum program requirements. Throughout this document, wherever the Streamlining 

Rule is addressed, POTW staff must remember that approved programs in existence at the time of the 

Streamlining Rule are likely based on the older, more restrictive requirements. To ensure that sufficient 

legal authority exists and that approved program and NPDES permit requirements are not violated, 

POTWs will, in most cases, need to modify their approved pretreatment programs before implementing 

the Streamlining Rule. EPA encourages POTWs to discuss that and all program modifications with their 

Approval Authority. The overall framework for the General Pretreatment Regulations is provided in 

figure 2-2. 

The General Pretreatment Regulations apply to all nondomestic sources that introduce pollutants 

into a POTW. These sources of indirect discharges are more commonly referred to as IUs. Because an IU 

can be as simple as an automated, coin-operated car wash or as complex as an automobile manufacturing 

plant or a synthetic organic chemical producer, EPA developed four criteria that define a significant IU 

(SIU). Many of the General Pretreatment Regulations apply to SIUs as opposed to IUs; the distinction is 

based on the presumption that control of SIUs will, in most cases, provide adequate protection of the 

POTW. Where a smaller IU has the potential to adversely affect the POTW, the POTW would be 

expected to designate the facility as an SIU. 

An SIU is defined in 40 CFR 403.3(v) as any of the following: 

 An IU subject to federal categorical pretreatment standards 

 An IU that discharges an average of 25,000 gallons per day (gpd) or more of process 

wastewater to the POTW 

 An IU that contributes a process wastestream making up 5 percent or more of the average 

dry-weather hydraulic or organic capacity of the POTW treatment plant 

2-2 Introduction to the National Pretreatment Program 
Chapter 2. Overview of the National Pretreatment Program 

Introduction to the National Pretreatment Program 2-3 

§403.1 Purpose and applicability 

§403.2 Objectives of general pretreatment regulations 

§403.3 Definitions 

§403.4 State or local law 

§403.5 National pretreatment standards: Prohibited 

discharges 

§403.6 National pretreatment standards: Categorical 

standards 

§403.7 Removal credits 

§403.8 Pretreatment program requirements: Development 

and Implementation by POTW 

§403.9 POTW pretreatment programs and/or authorization 

to revise pretreatment standards: Submission for 

approval 

§403.10 Development and submission of NPDES state 

pretreatment programs 

§403.11 Approval procedures for POTW pretreatment 

programs and POTW granting of removal credits 

§403.12 Reporting requirements for POTW's and industrial 

users 

§403.13 Variances from categorical pretreatment standards 

for fundamentally different factors 

§403.14 Confidentiality 

§403.15 Net/Gross calculation 

§403.16 Upset provision 

§403.17 Bypass 

§403.18 Modification of POTW pretreatment programs 

§403.19 Provisions of specific applicability to the Owatonna 

Waste Water Treatment Facility 

§403.20 Pretreatment Program Reinvention Pilot Projects 

under Project XL 

Appendix A: [Reserved] 

Appendix B: [Reserved] 

Appendix C: [Reserved] 

Appendix D: Selected Industrial Subcategories Considered 

Dilute for Purposes of the Combined Wastestream 

Formula 

Appendix E: Sampling Procedures 

Appendix F: [Reserved] 

Appendix G: Pollutants Eligible for a Removal Credit 

Figure 2-2. The General Pretreatment Regulations. 

 An IU designated by the 

POTW as such because of 

its reasonable potential to 

adversely affect the POTW's 

operation or violate any 

pretreatment standard or 

requirement. 

With the Streamlining Rule, EPA 

amended the pretreatment regulations so 

that the POTW may (although it is not 

required to) modify its approved 

pretreatment program to consider 

determining that a categorical industrial 

user (CIU)8

 is a nonsignificant categorical 

industrial user (NSCIU). To do that, the 

POTW must make a finding that the CIU 

never discharges more than 100 gpd of 

total categorical wastewater (excluding 

sanitary, noncontact cooling, and boiler 

blowdown wastewater, unless specifically 

included in the pretreatment standard) and 

the CIU meets all the following conditions 

as stated in 40 CFR 403.3(v)(2): 

 The IU, before the POTW’s 

finding, has consistently 

complied with all applicable 

categorical pretreatment 

standards and requirements. 

 The IU annually submits the 

certification statement 

required in section 

403.12(q), together with any 

additional information 

necessary to support the 

certification statement. 

 The IU never discharges any untreated concentrated wastewater. 

Designation as an NSCIU results in reduced reporting requirements for the NSCIU and reduced 

oversight requirements for the POTW. It does not in any way, however, relieve the industry of the need to 

comply with the categorical pretreatment standards. 

With the Streamlining Rule, EPA also amended the pretreatment regulations so that the POTW 

may (although it is not required to) modify its approved pretreatment program to classify a CIU as a 

middle-tier categorical industrial user (MTCIU) as described in 40 CFR 403.12(e)(3). The POTW may 

apply this classification to a CIU if its discharge of categorical wastewater does not exceed any of the 

following: 

 

8

 A CIU is an industrial user subject to national categorical pretreatment standards 
Chapter 1. POTWS and the Need for the Pretreatment Program 

2-4 Introduction to the National Pretreatment Program 

 0.01 percent of the design dry-weather hydraulic capacity of the POTW, or 5,000 gpd, 

whichever is smaller, as measured by a continuous effluent-flow-monitoring device unless 

the IU discharges in batches 

 0.01 percent of the design dry-weather organic treatment capacity of the POTW 

 0.01 percent of the maximum allowable headworks loading (MAHL) for any pollutant for 

which approved local limits were developed by a POTW. 

The POTW may apply the middle-tier classification only if the CIU has not been in significant 

noncompliance (SNC) for any time in the past two years and if the CIU does not have daily flow rates, 

production levels, or pollutant levels that vary so significantly that decreasing the reporting requirement 

for this IU would result in data that are not representative of conditions occurring during the reporting 

period. 

Unlike other environmental programs that rely on federal or state governments to implement and 

enforce specific requirements, under the National Pretreatment Program most of the responsibility rests 

on local municipalities. Thus, section 403.8(a) of the General Pretreatment Regulations provides that any 

POTW (or combination of treatment plants operated by the same authority) with a total design flow 

greater than 5 million gallons per day (mgd) and smaller POTWs in defined circumstances must establish 

a local pretreatment program to prevent pass through and interference. As of early 2011, approximately 

1,600 POTWs are required to have local programs. Although that represents only about 10 percent of the 

total treatment plants nationwide, those POTWs account for more than 80 percent (i.e., approximately 32 

billion gallons a day) of the wastewater flow nationwide. 

The General Pretreatment Regulations use two terms in describing responsibilities under the 

regulations. One is the term Control Authority. Under the regulations, where a POTW has an approved 

pretreatment program, the POTW is the Control Authority. If a POTW has not received approval of a 

pretreatment program submission, the Control Authority is either a state authorized to administer the 

National Pretreatment Program9

 or EPA. The term Approval Authority describes the party with 

responsibility to administer the National Pretreatment Program—either a state with an approved 

pretreatment program or, in a state without an approved pretreatment program, the EPA region for that 

state [40 CFR 403.3(f)]. Section 403.10(f)(2)(i) of the regulations requires the director of an NPDESauthorized state to develop procedures to address the requirements at 40 CFR 403.8(f)(2) for IUs 

discharging to a POTW without an approved pretreatment program (figure 2-3). In addition, CWA section 

403.10(e) provides a state with the option to implement the pretreatment programs for the POTWs in the 

state in lieu of requiring its POTWs to implement programs. Five states (Alabama, Connecticut, 

Mississippi, Nebraska, and Vermont) have elected to assume that responsibility. In such cases, the state is 

defined as the Control Authority for all IUs in the state. 

As described earlier, POTWs establish local pretreatment programs to control discharges from 

nondomestic sources. These programs must be approved by the Approval Authority, which is also 

responsible for overseeing implementation and enforcement of the programs. For the list of states and 

territories authorized to implement state NPDES permit programs and act as National Pretreatment 

Program Approval Authorities, see attachment 2-1. Visit http://cfpub.epa.gov/npdes/statestats.cfm for 

updates to this list. 

 

9

 An approved/authorized state is one with an NPDES permit program approved pursuant to CWA section 402(b) and an 

approved state pretreatment program. 
Chapter 2. Overview of the National Pretreatment Program 

§403.8(f)(2) POTW Pretreatment Requirements: Procedures 

§403.8(f)(2) (i) Identify and locate all possible IUs 

§403.8(f)(2) (ii) Identify character and volume of pollutants from IUs 

§403.8(f)(2) (iii) Notify IUs of applicable pretreatment standards 

§403.8(f)(2) (iv) Receive and analyze reports from IUs 

§403.8(f)(2) (v) Randomly sample and analyze effluent from IUs 

§403.8(f)(2) (vi) Evaluate whether IUs need slug discharge control plans 

§403.8(f)(2) (vii) Investigate instances of noncompliance 

§403.8(f)(2) (viii) Comply with public participation requirements 

Figure 2-3. POTW pretreatment requirements. 

POTW PRETREATMENT PROGRAMS

Once the determination has been made that a POTW needs a pretreatment program, the POTW’s 

NPDES permit is modified to require development of a local program and submission of the program 

elements to the Approval Authority for review and approval. Consistent with CWA section 403.8(f), 

POTW pretreatment programs must contain six minimum elements, presented in figure 2-4. 

In addition to the six specific elements, pretreatment program submissions must include the 

following [40 CFR 403.9(b)]: 

 A statement from the city solicitor (or the equivalent) declaring that the POTW has 

adequate authority to carry out program requirements 

 Copies of statutes, ordinances, regulations, agreements, or other authorities the POTW 

relies upon to administer the pretreatment program, including a statement reflecting the 

endorsement or approval of the bodies responsible for supervising or funding the program 

 A brief description and organizational chart of the organization administering the program 

 A description of funding levels and manpower available to implement the program. 

Pretreatment program submissions that are complete proceed to the public notice process, as 

described in chapter 4, Public Participation. Upon program approval, the Approval Authority is 

responsible for modifying the POTW’s NPDES permit to require implementation of the approved 

pretreatment program. Once the POTW pretreatment program has been approved, the Approval Authority 

oversees program implementation by receiving annual POTW reports and conducting periodic audits and 

inspections. 

Introduction to the National Pretreatment Program 2-5 
Chapter 1. POTWS and the Need for the Pretreatment Program 

1. Legal Authority 

The POTW must operate pursuant to legal authority enforceable in federal, state or local courts, which authorizes or 

enables the POTW to apply and enforce any pretreatment requirements developed pursuant to the CWA and 

implementing regulations. At a minimum, the legal authority must enable the POTW to 

i. Deny or condition discharges to the POTW; 

ii. Require compliance with pretreatment standards and requirements; 

iii. Control IU discharges through permits, orders, or similar means; 

iv. Require IU compliance schedules when necessary to meet applicable pretreatment 

standards and/or requirements and the submission of reports to demonstrate compliance; 

v. Inspect and monitor IUs; 

vi. Obtain remedies for IU noncompliance; and 

vii. Comply with confidentiality requirements. 

2. Procedures 

The POTW must develop and implement procedures to ensure compliance with pretreatment requirements, including 

i. Identifying and locating all IUs subject to the pretreatment program; 

ii. Identifying the character and volume of pollutants contributed by such users; 

iii. Notifying users of applicable pretreatment standards and requirements; 

iv. Receiving and analyzing reports from IUs; 

v. Sampling and analyzing IU discharges; 

vi. Evaluating the need for IU slug control plans; 

vii. Investigating instances of noncompliance; and 

viii. Complying with public participation requirements. 

3. Funding 

The POTW must have sufficient resources and qualified personnel to carry out the authorities and procedures 

specified in its approved pretreatment program. 

4. Local Limits 

The POTW must develop local limits in defined circumstances or demonstrate why these limits are not necessary. 

5. Enforcement Response Plan (ERP) 

The POTW must develop and implement an ERP that contains detailed procedures indicating how the POTW will 

investigate and respond to instances of IU noncompliance. 

6. List of SIUs 

The POTW must prepare, update, and submit to the Approval Authority a list of all SIUs and where applicable indicate 

which SIUs are NSCIUs or MTCIUs.

Figure 2-4. Six minimum pretreatment program elements. 

The National Pretreatment Program regulates IUs through three types of regulatory entities––

EPA, Approval Authorities, and Control Authorities. As noted above, Approval Authorities oversee 

Control Authorities, while Control Authorities regulate IUs. The general responsibilities of each of the 

three regulatory entities are presented in figure 2-5. 

2-6 Introduction to the National Pretreatment Program 
Chapter 2. Overview of the National Pretreatment Program 

EPA 

Headquarters 

 Oversees program implementation at all levels 

 Develops and modifies regulations for the program 

 Develops policies to clarify and further define the program 

 Develops technical guidance for program implementation 

 Initiates enforcement actions as appropriate 

Regions 

 Fulfill Approval Authority responsibilities for states without a state pretreatment program 

 Oversee state program implementation 

 Initiate enforcement actions as appropriate 

Approval Authorities (may be EPA Regions or authorized states) 

 Notify POTWs of their responsibilities 

 Review and approve requests for POTW pretreatment program approval or modification 

 Review requests for site-specific modifications to categorical pretreatment standards 

 Oversee POTW program implementation 

 Provide technical guidance to POTWs 

 Initiate enforcement actions against noncompliant POTWs or industries. 

Control Authorities (may be POTWs, states, or EPA regions) 

 Develop, implement, and maintain approved pretreatment program 

 Evaluate compliance of regulated IUs 

 Initiate enforcement action against industries as appropriate 

 Submit reports to Approval Authorities 

 Develop local limits where required (or demonstrate why they are not needed) 

 Develop and implement enforcement response plan 

 Review requests for net/gross variances 

Industrial Users 

 Comply with applicable pretreatment standards and reporting requirements 

Figure 2-5. Roles and responsibilities. 

Introduction to the National Pretreatment Program 2-7 
Chapter 1. POTWS and the Need for the Pretreatment Program 

ATTACHMENT 2-1: STATE AND TERRITORY PROGRAM AUTHORIZATION 

STATUS

State or territory 

Approved NPDES permit 

program 

Approved pretreatment 

program 

Alabama 10/19/1979 10/19/1979* 

American Samoa -- -- 

Alaska 10/31/2008 10/31/2008 

Arizona 12/05/2002 12/05/2002 

Arkansas 11/01/1986 11/01/1986 

California 05/14/1973 09/22/1989 

Colorado 03/27/1975 -- 

Connecticut 09/26/1973 06/03/1981* 

Delaware 04/01/1974 -- 

Florida 05/01/1995 05/01/1995 

Guam -- -- 

Georgia 06/28/1974 03/12/1981 

Hawaii 11/28/1974 08/12/1983 

Illinois 10/23/1977 -- 

Indiana 01/01/1975 -- 

Johnson Atoll -- -- 

Iowa 08/10/1978 06/03/1981 

Kansas 06/28/1974 -- 

Kentucky 09/30/1983 09/30/1983 

Louisiana 08/27/1996 08/27/1996 

Maine 01/12/2003 01/12/2003 

Maryland 09/05/1974 09/30/1985 

Midway Island -- -- 

Michigan 10/17/1973 04/16/1985 

Minnesota 06/30/1974 07/16/1979 

Mississippi 05/01/1974 05/13/1982* 

Missouri 10/30/1974 06/03/1981 

Montana 06/10/1974 -- 

Nebraska 06/12/1974 09/07/1984* 

Nevada 09/19/1975 -- 

New Jersey 04/13/1982 04/13/1982 

New York 10/28/1975 -- 

North Carolina 10/19/1975 06/14/1982 

Northern Mariana Islands -- -- 

North Dakota 06/13/1975 09/16/2005 

Ohio 03/11/1974 07/27/1983 

Oklahoma 11/19/1996 11/19/1996 

Oregon 09/26/1973 03/12/1981 

Puerto Rico -- -- 

2-8 Introduction to the National Pretreatment Program 
Chapter 2. Overview of the National Pretreatment Program 

Introduction to the National Pretreatment Program 2-9 

State or territory 

Approved NPDES permit 

program 

Approved pretreatment 

program 

Pennsylvania 06/30/1978 -- 

Rhode Island 09/17/1984 09/17/1984 

South Carolina 06/10/1975 04/09/1982 

South Dakota 12/30/1993 12/30/1993 

Tennessee 12/28/1977 08/10/1983 

Texas 09/14/1998 09/14/1998 

Utah 07/07/1987 07/07/1987 

Vermont 03/11/1974 03/16/1982* 

Virgin Islands 06/30/1976 -- 

Wake Island -- -- 

Virginia 03/31/1975 04/14/1989 

Washington 11/14/1973 09/30/1986 

West Virginia 05/10/1982 05/10/1982 

Wisconsin 02/04/1974 12/24/1980 

Wyoming 01/30/1975 -- 

* Denotes 403.10(e) state approval. 

Table is current as of March 2011.
Chapter 3. Pretreatment Standards 

1. 

CHAPTER 3. 

PRETREATMENT STANDARDS

Guidance Manual for Battery Manufacturing Pretreatment Standards (EPA August 1987) 

Guidance Manual for Electroplating and Metal Finishing Pretreatment Standard (EPA-440/1-84/091g) 

Guidance Manual for Iron and Steel Manufacturing Pretreatment Standards (EPA September 1985) 

Guidance Manual for Leather Tanning and Finishing Pretreatment Standards (EPA 833B86101) 

Guidance Manual for Pulp, Paper, and Paperboard and Builders’ Paper and Board Mills Pretreatment Standards

(EPA July 1984) 

Permitting Guidance for Semiconductor Manufacturing Facilities (EPA April 1998) 

Permit Guidance Document – Pulp, Paper and Paperboard Manufacturing Point Source Category 

(EPA 821-B-00-003) 

Permit Guidance Document – Transportation Equipment Cleaning (EPA 821-R-01-021) 

Small Entity Compliance Guide – CWT [Centralized Waste Treatment] (EPA 821-B-01-003) 

Product and Product Group Discharges (OCPSF) (EPA April 2005) 

Pollution Prevention (P2) Manual for the Pesticide Formulating Packaging and Repackaging Industry 

(EPA 821-B-98-017) 

Guidance Manual for the Use of Production-Based Pretreatment Standards and the Combined Wastestream Formula

(EPA 833/B-85-201) 

Local Limits Development Guidance (EPA 833R-04-002A, 2004) 

Guidance to Protect POTW Workers from Toxic and Reactive Gases and Vapors (EPA 812-B-92-001) 

Supplemental Manual on the Development and Implementation of Local Discharge Limitations under the 

Pretreatment Program: Residential and Commercial Toxic Pollutant Loadings and POTW Removal Efficiency 

Estimation (EPA 21W-4002) 

New Source Dates for Direct and Indirect Dischargers (EPA September 2006) 

Industry-Specific Guides 

Guidance Manual: Aluminum, Copper, and Nonferrous Metals Forming and Metal Powders Pretreatment Standards

(EPA 800B89001) 

Chapter 3. Applicable EPA Guidance 

Guidance Manual for Implementing Total Toxic Organics (TTO) Pretreatment Standards (EPA September 1985) 

Guidance Manual for Preparation and Review of Removal Credit Applications (EPA July 1985) 

Guidance Manual for Preventing Interference at POTWs (EPA 833/B-87-201) 

Guidance Manual for the Identification of Hazardous Wastes Delivered to Publicly Owned Treatment Works by Truck, 

Rail, or Dedicated Pipe (EPA 833/B-87-100) 

The National Pretreatment Program regulations identify specific requirements that apply to all 

IUs, additional requirements that apply to all SIUs, and certain requirements that apply only to CIUs. 

There are three types of national pretreatment requirements: 

 Prohibited discharge standards that include general and specific prohibition on discharges 

 Categorical pretreatment standards 

 Local limits. 

Introduction to the National Pretreatment Program 3-1 
Chapter 3. Pretreatment Standards 

PROHIBITED DISCHARGE STANDARDS

All IUs—regardless of whether they are subject to any other national, state, or local pretreatment 

requirements—are subject to the general and specific prohibitions identified in 40 CFR 403.5(a) and (b), 

respectively. General prohibitions forbid the discharge (the regulations use the term introduction) of any 

pollutant(s) to a POTW that cause pass through or interference. Pass through and interference are terms 

with very specific meaning in the regulations. Pass through is defined as a discharge that exits the POTW 

into waters of the United States in quantities or concentrations that, alone or in conjunction with a 

discharge or discharges from other sources, is a cause of a violation of any requirement of the POTW's 

NPDES permit. Interference is defined as a discharge that, alone or in conjunction with a discharge or 

discharges from other sources, both (1) inhibits or disrupts the POTW, its treatment processes or 

operations, or its sludge processes, use, or disposal and (2) therefore is a cause of a violation of any 

requirement of the POTW's NPDES permit. Specific prohibitions in 40 CFR 403.5(b) forbid the 

following eight categories of pollutant discharges: 

 Discharges containing pollutants that create a fire or explosion hazard in the POTW, 

including wastestreams with a closed-cup flashpoint of less than 140 °F (60 °C) using the 

test methods specified in 40 CFR 261.21 

 Discharges containing pollutants causing corrosive structural damage to the POTW, but in 

no case discharges with a pH lower than 5.0, unless the POTW is specifically designed to 

accommodate such discharges 

 Discharges containing pollutants in amounts causing obstruction to the flow in the POTW 

resulting in interference 

 Discharges of any pollutants released at a flow rate or concentration that will cause 

interference with the POTW 

 Discharges of heat in amounts that will inhibit biological activity in the POTW resulting in 

interference, but in no case heat in such quantities that the temperature at the POTW 

treatment plant exceeds 104 °F (40 °C) unless the Approval Authority, at the POTW’s 

request, approves alternative temperature limits 

 Discharges of petroleum oil, nonbiodegradable cutting oil, or products of mineral oil origin 

in amounts that will cause interference or pass through 

 Discharges that result in the presence of toxic gases, vapors, or fumes within the POTW in 

a quantity that could cause acute worker health and safety problems 

 Discharges of trucked or hauled pollutants, except at discharge points designated by the 

POTW. 

Compliance with the general and specific prohibitions is mandatory for all IUs. The prohibited 

discharge standards are intended to provide general protection for POTWs. To address site-specific 

conditions, POTWs might also need to develop more specific limitations or additional controls to prevent 

pass through and interference. In addition to the prohibitions described above, IUs are also subject to 

categorical pretreatment standards and local limits. 

EFFLUENT GUIDELINES AND CATEGORICAL PRETREATMENT 

STANDARDS DEVELOPMENT

Effluent limitations guidelines, also referred to as effluent guidelines, are national standards 

developed by EPA on an industry-by-industry basis, and they are intended to represent the greatest 

pollutant reductions economically achievable for an industry. To develop these technology-based 

3-2 Introduction to the National Pretreatment Program 
Chapter 3. Pretreatment Standards 

Introduction to the National Pretreatment Program 3-3 

regulations, EPA first gathers information on the industry's practices; characteristics of discharges 

(stormwater flows and pollutants); technologies or practices used to prevent or treat the discharges; and 

economic characteristics. EPA identifies the best available technology that is economically achievable for 

that industry and sets regulatory requirements based on the performance of that technology. The effluent 

guidelines do not require facilities to install the particular technology identified by EPA; however, the 

regulations do require facilities to achieve the regulatory standards that were developed based on a 

particular model technology. Effluent limitations guidelines are implemented through the NPDES permit 

program. Discharges from direct dischargers (i.e., facilities that discharge wastewaters directly into waters 

of the United States) are regulated in permits that specify limits using Best Practicable Control 

Technology Currently Available (BPT), Best Available Technology Economically Achievable (BAT), 

Best Conventional Pollutant Control Technology (BCT), and New Source Performance Standards 

(NSPS). 

Pretreatment standards are implemented through the National Pretreatment Program. Discharges 

from indirect dischargers (i.e., facilities that discharge their wastewaters to a POTW) are regulated 

through categorical standards issued based on Pretreatment Standards for New Sources (PSNS) and 

Pretreatment Standards for Existing Sources (PSES). 

Industries identified as major sources of pollutants are typically prioritized for effluent guideline 

and categorical standard development. EPA typically summarizes the industries it is investigating for 

potential rulemakings and the related data collection and reviews in its Effluent Guidelines Program Plan. 

The biennial plans are published in the Federal Register, and EPA solicits public comment before 

finalizing them.10 If limits are deemed necessary, EPA initiates a rulemaking, investigates affected 

industrial sectors, and gathers information regarding process operations and treatment and management 

practices, accounting for differences in facility size and age, equipment age, and wastewater 

characteristics.11 Subcategorization within an industrial category is evaluated on the basis of variability in 

processes employed, raw materials used, types of items produced, and characteristics of wastes generated. 

Availability and cost of control technologies, non-water-quality environmental effects, available pollution 

prevention measures,12 and economic effects are evaluated before EPA presents its findings in proposed 

development documents and publishes a notice of the proposed regulations in the Federal Register. After 

making any revisions reflecting public comments on the proposed rule, EPA promulgate (publishes) the 

standards (figure 3-1). EPA encourages all stakeholders, including pretreatment professionals, to review 

EPA’s proposed categorical standards and provide data and comments during the public comment period. 

A list of the industrial categories that have categorical pretreatment standards is provided as attachment 

3-1. 

 

10 The latest information on EPA’s Effluent Guidelines Program Plans and when to submit comments is at 

http://epa.gov/guide/304m/index.html. 11 See EPA’s Effluent Guidelines Web page (http://epa.gov/guide) or the most recent Federal Regulatory Agenda, which is 

published twice a year (usually in April and October) in the Federal Register. For a listing of all ongoing effluent guidelines 

rulemakings, see http://www.gpoaccess.gov/ua. 12 For more information on this topic, refer to EPA's Considerations of Pollution Prevention in EPA’s Effluent Guideline 

Development Process. 
Chapter 3. Pretreatment Standards 

3-4 Introduction to the National Pretreatment Program 

Data

Collection

Regulatory

Tasks

Proposed

Development

Document

Proposed

Regulations

Public

Comment

Promulgation of

Final

Regulations

Final

Development

Document

Revisions

Figure 3-1. The Effluent guideline development process. 

As noted earlier, categorical pretreatment standards may be developed for both existing sources 

(PSES) and new sources (PSNS). Facilities are classified as either PSES or PSNS on the basis of the 

definition of new source set forth in 40 CFR 403.3(m) of the General Pretreatment Regulations (figure 

3-2). Dischargers subject to PSES are required to comply with those standards by a specified date, 

typically no more than 3 years after the effective date of the categorical standard. Users subject to PSNS, 

however, are required to achieve compliance within the shortest feasible time, not to exceed 90 days from 

commencement of discharge. PSNS are often more stringent than PSES because of the opportunity for 

new sources to install the best available demonstrated technology and operate the most efficient 

production processes. For additional information on EPA’s regulatory requirements for determining 

which sources are new sources, see the New Source Memorandum on EPA’s website at 

http://www.epa.gov/npdes/pretreatment. That document provides a summary of relevant regulatory 

criteria for consideration in this determination, as well as a listing of applicable new source dates used in 

making new source determinations. 

EPA typically does not establish pretreatment standards for conventional pollutants (e.g., BOD, 

TSS, oil and grease) because POTWs are designed to treat those pollutants. EPA has, however, exercised 

its authority to establish some categorical pretreatment standards for conventional pollutants as surrogates 

for toxic or nonconventional pollutants or to prevent interference. For example, EPA established 

categorical pretreatment standards for new and existing sources with a 1-day maximum concentration of 

100 mg/L oil and grease in the Petroleum Refining Point Source Category (40 CFR Part 419) based on 

“the necessity to minimize [the] possibility of slug loadings of oil and grease being discharged to 

POTWs.”13

 

13 Refer to U.S. Environmental Protection Agency, Interim Final Supplement for Pretreatment to the Development Document 

for the Petroleum Refining Industry Existing Point Source Category, EPA-440-1-76-083A (1977), p. 92. 
Chapter 3. Pretreatment Standards 

New source is defined at 40 CFR 403.3(m)(1) as any building, structure, facility, or installation from which there is or may be a 

discharge of pollutants, the construction of which commenced after publication of proposed pretreatment standards under 

section 307(c) of the act which will be applicable to such source if standards are thereafter promulgated in accordance with that 

section, provided that: 

i. The building, structure, facility, or installation is constructed at a site at which no other source is 

located; or 

ii. The building, structure, facility, or installation totally replaces the process or production equipment that 

causes the discharge of pollutants at an existing source; or 

iii. The production or wastewater generating processes of the building, structure, facility or installation are 

substantially independent of an existing source at the same site. In determining whether these are 

substantially independent, factors such as the extent to which the new facility is integrated with the 

existing plant and the extent to which the new facility is engaged in the same general type of activity as 

the existing source should be considered. 

(2) Construction on a site at which an existing source is located results in a modification rather than a new 

source if the construction does not create a new building, structure, facility, or installation meeting the 

criteria of paragraphs (m)(1)(ii), or (m)(1)(iii) of this section but otherwise alters, replaces, or adds to 

existing process or production equipment. 

(3) Construction of a new source as defined under this paragraph has commenced if the owner or operator 

has: 

i. Begun, or caused to begin as part of a continuous onsite construction program (A) Any placement, 

assembly or installation of facilities or equipment, or (B) significant site preparation work, including 

clearing, excavation, or removal of existing buildings, structures, or facilities which is necessary for the 

placement, assembly, or installation of new source facilities or equipment; or 

ii. Entered into a binding contractual obligation for the purchase of facilities or equipment which are 

intended to be used in its operation within a reasonable time. Options to purchase or contracts which 

can be terminated or modified without substantial loss, and contracts for feasibility, engineering, and 

design studies do not constitute a contractual obligation under this paragraph. 

Figure 3-2. Definition of new source [40 CFR 403.3(m)]. 

EPA has established the following types of categorical pretreatment standards for certain 

industrial sectors: 

 Concentration-based standards that are implemented directly as concentration limits 

 Mass limits based on production rates 

 Both concentration-based and production-based limits 

 Mass limits based on a concentration standard multiplied by a facility’s process wastewater 

flow 

 Standards that allow for the use of best management practices (BMPs) 

 Standards that prohibit discharge of any kind. 

EPA generally establishes concentration-based categorical pretreatment standards when 

production and achievable wastewater flow cannot be normalized on a national basis. Productionnormalized, mass-based standards are calculated from production-normalized flows (volume of 

wastewater/production unit) and incorporate wastewater flow reductions representing BAT (which is the 

technology basis for PSES) or best available demonstrated technology (which is the technology basis for 

PSNS). Flow-normalized, mass-based, and concentration-based standards can consider flow reduction 

when estimating the PSES and PSNS incremental compliance costs; however, the standards themselves 

do not specifically require flow reductions to maintain compliance. The last type of mass limits described 

can be calculated by using a reasonable measure of the IU's actual long-term daily production (for 

production-normalized, mass-based standards) or the IU's actual long-term average daily flow rate (for 

flow-normalized, mass-based, concentration-based standards). EPA prefers setting productionnormalized, mass-based standards, where feasible, because production-normalized limitations can account 

for flow reduction and reduce the potential for using dilution instead of actual treatment to reduce a 

concentration value in the effluent. 

Introduction to the National Pretreatment Program 3-5 
Chapter 3. Pretreatment Standards 

LOCAL LIMITS

The general and specific prohibited discharge standards are designed to protect against pass 

through and interference generally. Categorical pretreatment standards, on the other hand, are designed to 

ensure that IUs implement technology-based controls to limit the introduction of pollutants to the POTW. 

Local limits address the specific needs and concerns of a POTW, its sludge, and its receiving waters. The 

federal regulations at 40 CFR 403.8(f)(4) and 122.21(j)(4) require POTWs to evaluate the need for local 

limits and, if necessary, implement and enforce specific limits as part of pretreatment program activities. 

Local limits are developed for pollutants that could cause interference, pass through, sludge 

contamination, or worker health and safety problems if discharged in excess of the receiving POTW 

treatment plant’s capabilities or receiving water quality standards. Typically, local limits are developed to 

regulate the discharge from all SIUs, not just CIUs, and they are usually imposed at the end-of-pipe

discharge from an IU (i.e., at the point of connection to the POTW's collection system). In evaluating the 

need for local limits development, it is recommended that POTWs do the following: 

 Conduct an industrial waste survey to identify all IUs that might be subject to the 

pretreatment program. 

 Determine the character and volume of pollutants contributed to the POTW by these 

industries. 

 Determine which pollutants have a reasonable potential for pass through, interference, or 

sludge contamination as these terms are defined in EPA’s pretreatment regulations. 

 Identify additional pollutants of concern. 

Maximum Allowable Headworks Loading 

(MAHL). Treatment plant data are used to calculate 

removal efficiencies for each pollutant to backcalculate the MAHLs before applying the most 

stringent criteria (i.e., water quality, sludge quality, 

NPDES permit, or pollutant inhibition levels). 

Subtracting contributions from unpermitted 

sources, the available industrial loading is then 

either evenly distributed among the IUs or allocated 

on an as-needed basis to those IUs discharging the 

pollutant above background levels. 

Figure 3-3. MAHL. 

Maximum Allowable Industrial Load (MAIL). The 

MAIL is the total daily mass that a POTW can 

accept from all permitted IUs and still ensure that 

the POTW is protecting against pass through and 

interference. 

Figure 3-4. MAIL.

 Conduct a technical evaluation to determine 

the maximum allowable headworks (influent) 

loading (MAHL) for at least ammonia (for 

plants that accept nondomestic sources of 

ammonia), arsenic, BOD5, cadmium, 

chromium, copper, cyanide, lead, mercury, 

molybdenum, nickel, selenium, silver, TSS, 

and zinc (figure 3-3). 

 Determine contributions from background 

sources (e.g., residential and commercial) to 

determine the MAHL from controllable

industrial sources (figure 3-4). 

 Implement a system to ensure that such 

MAHLs will not be exceeded. 

As stated in EPA’s 2004 Local Limits Development 

Guidance, when POTWs evaluate a pollutant for the first 

time, they should assume that local limits are needed when 

any of the following are true: 

 The average influent loading of a toxic pollutant exceeds 60 percent of the MAHL. 

 The maximum daily influent loading of a toxic pollutant exceeds 80 percent of the MAHL 

at any time in the 12-month period preceding the analysis. 

 The monthly average influent loading reaches 80 percent of the average design capacity 

for BOD5, TSS, and ammonia during any one month in the 12-month period preceding the 

analysis. 

3-6 Introduction to the National Pretreatment Program 
Chapter 3. Pretreatment Standards 

Those percentages that trigger local limits development are default assumptions that can vary 

from plant to plant. The approach used for toxic pollutants is more conservative because most POTWs are 

not designed to treat toxic pollutants. For more details, refer to EPA’s Local Limits Development 

Guidance.

Other local limit approaches available to POTWs are the following: 

 Collection system approach. Pollutants found to be present that could cause fire and 

explosion hazards or other worker health and safety concerns are evaluated for their 

propensity to volatilize and are modeled to evaluate their expected concentration in air. 

Comparisons are made with worker health exposure criteria and lower explosive limits. 

Where values are of concern, the POTW may set limits or require development of 

management practices to control undesirable discharges. With such an approach, the POTW 

may also consider the prohibition of pollutants with specific flashpoints to prevent discharges 

of ignitable wastes. EPA’s Guidance to Protect POTW Workers from Toxic and Reactive 

Gases and Vapors and EPA’s 2004 Local Limits Development Guidance detail strategies for 

developing such local limits. In addition to the low-end pH limit specified in the General 

Pretreatment Regulations, the 2004 Local Limits Development Guidance also recommends 

that POTWs evaluate the need to set upper pH limits or more stringent low-end pH limits. A 

POTW should set an upper pH limit if corrosion damage attributable to high-pH discharges is 

identified. In addition, with the collection system approach, the POTW may consider 

pollutants in amounts that will obstruct flows to the POTW and result in interference. As 

stated in the 2004 Local Limits Development Guidance, the greatest threat of obstruction in 

POTWs comes from polar fats, oils, and greases (FOG) of animal and vegetable origin. Polar 

FOG can accumulate and congeal in collection systems, pumping stations, and treatment 

plants. It can interfere with the POTW’s collection system through blockages when the 

wastewater cools enough to allow the suspended FOG to congeal. 

 Case-by-case discharge limits. Such numeric local limits are based on best professional 

judgment and available pollution-prevention and treatment technologies that have been 

shown through case studies to be economically feasible. Such an approach is most often used 

when insufficient data are available to employ the methods outlined earlier. 

 Best management practices. BMPs are management and operational procedures that are 

intended to prevent pollutants from entering a facility’s wastestream or from reaching a 

discharge point. BMPs also include treatment requirements; operating procedures; sludge or 

waste disposal; management of drainage from raw materials storage; oil and grease collection 

requirements; and practices to control plant site runoff, spillage, or leaks. BMPs should be 

enforceable, and they may be used as the local limits required by 40 CFR 403.5(c). 

 Local specific prohibitions. POTW-specific prohibitions may be imposed under local law in 

addition to the prohibitions detailed in 40 CFR 403.5 (a) and (b) to address hydraulic, 

pollutant-specific, or aesthetic concerns. Following are examples: 

– Noxious or malodorous liquids, gases, or solids creating a public nuisance 

– Wastestreams that impart color and pass through the POTW treatment plant 

– Stormwater, roof runoff, swimming pool drainage 

– Wastewaters containing radioactive wastes or isotopes 

– Removed substances from pretreatment of wastewater 

Introduction to the National Pretreatment Program 3-7 
Chapter 3. Pretreatment Standards 

Regardless of the approaches that a POTW takes, local limits should correct existing problems, 

prevent potential problems, protect the receiving waters, improve sludge use options, and protect POTW 

personnel. EPA’s Local Limits Development Guidance and Guidance for Preventing Interference at 

POTWs provide basic information on the subject. In addition, many EPA Regions and states have 

developed local limits guidance to address regional and state issues. 

SUMMARY OF STANDARDS 

A general summary of all the pretreatment standards, including general and specific prohibitions, 

categorical pretreatment standards, and local limits, is provided in figure 3-5. A summary of specific 

categorical standards is presented in Attachment 3-1. 

General and 

specific 

prohibitions 

Categorical pretreatment 

standards Local limits 

Development Established at the 

federal level. 

Established at the federal level. Developed by the POTWs. 

Reference 40 CFR 403.5(a) & 

(b) 

40 CFR Parts 405–471 Requirements for development 

found in 40 CFR 403.5(c) & 

403.8(f)(4). Local limits are often 

found in the local sewer use 

ordinance. 

Applicability All IUs CIUs Commonly all IUs or all SIUs, but 

depends on the allocation method 

used when developing limits. 

Purpose Provide for general 

protection of the 

POTW. Categorical 

pretreatment 

standards or local 

limits may be more 

stringent. 

Minimum standards based on 

available treatment technology and 

pollution prevention measures for 

controlling nonconventional and 

toxic pollutants that could cause 

pass through, interference, and 

such at the POTW. Local limits may 

be more stringent. 

Provide site-specific protection for 

a POTW and its receiving waters. 

Categorical standards may be 

more stringent. 

All standards are considered pretreatment standards for the purpose of CWA section 307(d), and therefore all 

standards, including local limits developed in accordance with 40 CFR 403.5(c), are enforceable by EPA and the state 

even though they might be developed at the local level. A POTW is responsible for identifying standard(s) applicable 

to each IU and applying the most stringent requirements where multiple provisions exist. Compliance with imposed 

standards can be achieved by any of the following: implementing BMPs, developing a pollution prevention program, or 

installing pretreatment. 

Figure 3-5. Summary of standards. 

3-8 Introduction to the National Pretreatment Program 
Chapter 3. Pretreatment Standards 

ATTACHMENT 3-1: SUMMARY OF CATEGORICAL STANDARDS

EPA has established categorical pretreatment standards (for indirect dischargers) for 35 

categories. Plans for EPA’s expansion and modification of the list are detailed in the Effluent Guidelines 

Plan, published in the Federal Register biennially as required at CWA section 304(m). The list of the 

industrial categories that have categorical pretreatment standards—Pretreatment Standards for Existing 

Sources (PSES) and Pretreatment Standards for New Sources (PSNS)—as of March 2011 is provided 

below. 

Summary of categorical pretreatment standards 

No. Category 

40 

CFR 

Part Subparts 

Type of 

standard Overview of pretreatment standards 

1 Aluminum Forming 467 A–F PSES 

PSNS 

Limits are production-based daily 

maximums and monthly averages. 

Subpart C prohibits discharges from 

certain operations. 

2 Battery 

Manufacturing 

461 A–G PSES 

PSNS 

Limits are production-based daily 

maximums and monthly averages. No 

discharge is allowed from any process 

not specifically identified in the 

regulations. 

3 Carbon Black 

Manufacturing 

458 A–D PSNS Limits are for oil and grease only (no 

duration specified). 

4 Centralized Waste 

Treatment 

437 A–D PSES 

PSNS 

Limits are concentration-based daily 

maximums and monthly averages. 

5 Coil Coating 465 A–D PSES 

PSNS 

Limits are production-based daily 

maximums and monthly averages. 

6 Concentrated 

Animal Feeding 

Operations (CAFO) 

412 B PSNS Discharge of process wastewater is 

prohibited, except when there is an 

overflow resulting from a chronic or 

catastrophic rainfall event. 

7 Copper Forming 468 A PSES 

PSNS 

Limits are production-based daily 

maximums and monthly averages. 

8 Electrical and 

Electronic 

Components 

469 A–D PSES 

PSNS 

Limits are concentration-based daily 

maximums and 30-day averages or 

monthly averages (varies per subpart 

and pollutant parameter). Certification is 

allowed in lieu of monitoring for certain 

pollutants when a management plan is 

approved and implemented. 

9 Electroplating 413 A,B,D–H PSES Limits are concentration-based (or 

alternative mass-based equivalents) 

daily maximums and four-consecutivemonitoring-days averages. Two sets of 

limits exist, depending on whether facility 

is discharging more or less than 10,000 

gpd of process wastewater. Certification 

is allowed in lieu of monitoring for certain 

pollutants when a management plan is 

approved and implemented. 

Introduction to the National Pretreatment Program 3-9 
Chapter 3. Pretreatment Standards 

3-10 Introduction to the National Pretreatment Program 

No. Category 

40 

CFR 

Part Subparts 

Type of 

standard Overview of pretreatment standards 

10 Fertilizer 

Manufacturing 

418 A–G PSNS Limits may specify zero discharge of 

wastewater pollutants (Subpart A), 

production-based daily maximums, and 

30-day averages (Subparts B–E), or 

may be concentration-based (Subparts 

F–G), with no duration of limit specified. 

11 Glass 

Manufacturing 

426 H 

K–M 

PSNS Limits are concentration- or productionbased daily maximums and monthly 

averages. 

12 Grain Mills 406 A PSNS Discharge of process wastewater is 

prohibited at a flow rate or mass loading 

rate (BOD5 and TSS) that is excessive 

during periods when a POTW is 

receiving peak loads. 

13 Ink Formulating 447 A PSNS Regulations specify no discharge of 

process wastewater pollutants to a 

POTW. 

A,B,F,L, 

AH,AJ,AL,

AR,AU,BC, 

BL,BM,BO 

14 Inorganic PSES 

Chemicals 

Manufacturing 

415 

B–F, H, 

K–N,P,Q, 

T,V,AA, 

AC,AE,AH 

AI,AJ,AL, 

AN,AP,AQ 

AR,AU,AX 

BB,BC, 

BH, 

BK–BO 

PSNS 

Limits vary for each subpart with a 

majority of the limits concentrationbased, daily maximums, and 30-day 

averages, or they may specify no 

discharge of wastewater pollutants. 

15 Iron and Steel 

Manufacturing 

420 A–F, H–J, 

L 

PSES 

PSNS 

Limits are production-based daily 

maximums and 30-day averages. 

16 Leather Tanning 

and Finishing 

425 A–I PSES 

PSNS 

Limits are concentration-based daily 

maximums and monthly averages. In 

certain instances, applicability of 

pretreatment standards is dictated by 

volume of production. 

17 Metal Finishing 433 A PSES 

PSNS 

Limits are concentration-based daily 

maximums and monthly averages. 

Certification is allowed for certain 

pollutants where a management plan is 

approved and implemented. 

18 Metal Molding and 

Casting 

464 A–D PSES 

PSNS 

Limits are primarily production-based 

daily maximums and monthly averages. 

Discharges from certain processes are 

prohibited (Subparts A–C). 

19 Nonferrous Metals 

Forming and Metal 

Powders 

471 A–J PSES 

PSNS 

Limits are production-based daily 

maximums and monthly averages. In 

some instances, the discharge of 

wastewater pollutants is prohibited. 
Chapter 3. Pretreatment Standards 

Introduction to the National Pretreatment Program 3-11 

No. Category 

40 

CFR 

Part Subparts 

Type of 

standard Overview of pretreatment standards 

C,F–M,P, 

Q,V,X,Y, 

AA–AC 

PSES Limits are production-based daily 

maximums and monthly averages. 

PSES (Subpart F) specify no discharge 

from existing facilities of process 

wastewater pollutants to the POTW 

except for some stormwater events. 

20 Nonferrous Metals 

Manufacturing 

421 

A–Z, 

AA–AE 

PSNS Limits are production-based daily 

maximums and monthly averages. 

PSNS (Subparts D and F) specify no 

discharge from existing facilities of 

process wastewater pollutants to the 

POTW. 

21 Oil and Gas 

Extraction 

435 D PSES 

PSNS 

Regulations specify no discharge of 

wastes (e.g., produced water, drill 

cuttings) to a POTW. 

22 Organic Chemicals, 

Plastics, and 

Synthetic Fibers 

414 B–H, K PSES 

PSNS 

Limits are mass-based (concentrationbased standards multiplied by process 

flow) daily maximums and monthly 

averages. Standards for metals and 

cyanide apply only to metal- or cyanidebearing wastestreams. 

23 Paint Formulating 446 A PSNS Regulations specify no discharge of 

process wastewater pollutants to the 

POTW. 

24 Paving and Roofing 

Materials (Tars and 

Asphalt) 

443 A–D PSNS Limits are for oil and grease only (no 

limit duration specified). 

25 Pesticide Chemicals 455 A, C, E PSES 

PSNS 

Limits are mass-based (concentrationbased standards multiplied by process 

flow) daily maximums and monthly 

averages. Subpart C specifies no 

discharge of process wastewater 

pollutants but provides for pollutionprevention alternatives. Subpart E 

specifies no discharge of process 

wastewater pollutants. 

26 Petroleum Refining 419 A–E PSES 

PSNS 

Limits are concentration-based (or 

mass-based equivalent) daily 

maximums. 

27 Pharmaceutical 

Manufacturing 

439 A–D PSES 

PSNS 

Limits are concentration-based daily 

maximums and monthly averages. Such 

facilities may certify that they do not use 

or generate cyanide in lieu of performing 

monitoring to demonstrate compliance. 

28 Porcelain 

Enameling 

466 A–D PSES 

PSNS 

Limits are concentration-based (or 

alternative production-based) daily 

maximums and monthly averages. 

Subpart B prohibits discharges from 

certain operations. 
Chapter 3. Pretreatment Standards 

3-12 Introduction to the National Pretreatment Program 

No. Category 

40 

CFR 

Part Subparts 

Type of 

standard Overview of pretreatment standards 

29 Pulp, Paper, and 

Paperboard 

430 A–G, I–L PSES 

PSNS 

Limits are production-based daily 

maximums and monthly averages. Such 

facilities may certify that they do not use 

certain compounds in lieu of performing 

monitoring to demonstrate compliance. 

Facilities subject to Subparts B and E 

must also implement BMPs as identified.

30 Rubber 

Manufacturing 

428 E–K PSNS Limits are concentration- or productionbased daily maximums and monthly 

averages. 

31 Soap and Detergent 

Manufacturing 

417 O–R PSNS Regulations specify no discharge of 

process wastewater pollutants to a 

POTW when the wastewater chemical 

oxygen demand (COD)/BOD7 ratio 

exceeds 10.0 and the COD 

concentrations exceed subcategory 

specific concentrations. 

32 Steam Electric 

Power Generating 

423 — PSES 

PSNS 

Limits are concentration-based daily 

maximums, or maximums for any time, 

or compliance may be demonstrated 

through engineering calculations. 

33 Timber Products 

Processing 

429 F–H PSES 

PSNS 

All PSNS (and PSES for Subpart F) 

prohibit the discharge of wastewater 

pollutants. PSES for Subparts G and H 

are concentration-based daily 

maximums (with production-based 

alternatives). 

34 Transportation 

Equipment Cleaning 

442 A–C PSES 

PSNS 

Operators subject to effluent guidelines 

in subparts A–B must either meet 

concentration-based daily maximum 

standards or develop a Pollutant 

Management Plan. Operators subject to 

effluent guidelines in subpart C must 

meet concentration-based daily 

maximum standards. 

35 Waste Combustors 444 A PSES 

PSNS 

Limits are concentration-based daily 

maximums and monthly averages. 
Chapter 4. POTW Pretreatment Program Responsibilities 

2. 

CHAPTER 4. 

POTW PRETREATMENT PROGRAM 

RESPONSIBILITIES

Chapter 4. Applicable EPA Guidance 

CERCLA Site Discharges to POTWs Guidance Manual (EPA 540G90005) 

Control of Slug Loadings to POTWs: Guidance Manual (EPA 21W-4001) 

Guidance for Developing Control Authority Enforcement Response Plans (EPA September 1989) 

Guidance Manual for POTWs to Calculate the Economic Benefit of Noncompliance (EPA 833B93007) 

Industrial User Inspection and Sampling Manual for POTWs (EPA 831-B-94-001) 

Industrial User Permitting Guidance Manual (EPA September 1989) 

Model Pretreatment Ordinance (EPA 833B06002) 

Multijurisdictional Pretreatment Programs: Guidance Manual (EPA 833-B-94-005) 

NPDES Compliance Inspection Manual (EPA July 2004) 

POTW Sludge Sampling and Analysis Guidance Document (EPA 833-B-89-100) 

Pretreatment Compliance Monitoring and Enforcement Guidance (EPA July 1986) 

RCRA Information on Hazardous Wastes for Publicly Owned Treatment Works (EPA 833/B-85-2025) 

Chapter 2 describes the basis on which POTWs can develop pretreatment programs that 

implement federal pretreatment standards and requirements, in addition to providing protection to address 

any local concerns. This chapter provides an overview of those POTW programs, highlighting each of the 

specific areas that the pretreatment program is to address. In cases where POTWs are not required to 

develop a pretreatment program, an approved state or EPA region is the Control Authority and must 

address the requirements in 40 CFR 403.8(f)(2). 

LEGAL AUTHORITY

As discussed in chapter 2, POTWs seeking pretreatment program approval must develop policy 

and procedures for program implementation and establish the legal authority to implement and enforce 

program requirements. The General Pretreatment Regulations do not provide POTWs with the legal 

authority to carry out their pretreatment programs; rather, the regulations set forth the minimum 

requirements for POTWs that are required to implement a pretreatment program. 

A POTW’s legal authority derives from state law. Therefore, state law must confer the minimum 

legal authority required by the General Pretreatment Regulations on a POTW. Where state law is 

deficient, it will need to be amended to provide the minimum requirements. 

To apply the regulatory authority provided by state law, it is usually necessary for the POTW to 

establish local regulations to legally implement and enforce pretreatment requirements. Where the POTW 

is a municipality, legal authority is typically spelled out in a sewer use ordinance (SUO), which is usually 

part of the city or county code. Regional POTWs frequently adopt similar provisions in the form of rules 

and regulations. Likewise, state agencies implementing a statewide program under 40 CFR 403.10(e) set 

Introduction to the National Pretreatment Program 4-1 
Chapter 4. POTW Pretreatment Program Responsibilities 

out pretreatment requirements as state regulations, rather than as an SUO. EPA’s 2007 guidance EPA 

Model Pretreatment Ordinance provides a model for POTWs that are required to develop pretreatment 

programs. 

As POTW service areas expand, new 

contributions can arise from extrajurisdictional IUs––

those outside the POTW’s legal jurisdiction (Figure 4-1). 

Multijurisdictional arrangements require special 

legal/contractual mechanisms to ensure adequate 

authority to implement and enforce program 

requirements in multiple jurisdictions. Some state 

statutes might provide for general extraterritorial powers 

(i.e., a POTW is automatically allowed to regulate 

extrajurisdictional IUs contributing to its system). 

However, the extent to which authorities (e.g., to permit, 

inspect, enforce, and/or monitor) are granted might be 

somewhat limited, thereby restricting a POTW’s ability 

to implement and enforce a program. Where obtaining 

authority from the state to regulate extrajurisdictional IUs 

is not feasible, the POTW may pursue other options: 

Figure 4-1. Multijurisdictional program.

 Districts. Creating an independent organization (by affected municipalities or the state) 

that is authorized to administer and enforce an approved pretreatment program for the 

entire area in which it provides services is common in areas where multiple POTWs serve 

various jurisdictions. 

 Agreements. Affected POTWs may opt to enter into agreements either requiring each 

municipality to implement and enforce the approved pretreatment program covering all

IUs within its jurisdiction or providing the POTW with the ability to implement and 

enforce the program within that municipality. If the other municipality is to implement the 

program, the POTW must, at a minimum, retain the means to regulate extrajurisdictional 

IUs where the contributing jurisdiction’s efforts are inadequate. It is essential that 

agreements clearly define the roles of each party. 

 Annexation. Where extrajurisdictional IUs are in unincorporated areas, a POTW may 

annex or utility-annex the service area. 

 Contracts. A POTW may enter into a contract with an extrajurisdictional IU, although 

contracts typically limit the enforcement capabilities of the POTW. Contracts, therefore, 

should be pursued only when all other means fail. 

Because procedures for obtaining jurisdiction, creating sanitary districts, annexing service areas, 

and so forth vary among states, POTW personnel should consult with legal staff to thoroughly examine 

the options allowed under state law. These could include requesting state legislative changes if necessary. 

EPA’s 1994 Multijurisdictional Pretreatment Programs—Guidance Manual provides more information 

on these jurisdictional issues, including sample language for agreements and contracts. 

INDUSTRIAL WASTE SURVEYS

As part of program development and maintenance, the federal regulations [40 CFR 403.8(f)(2)(i) 

and 40 CFR 122.44(j)(1)] require POTWs to identify and locate all IUs that might be subject to the 

pretreatment program. The POTW must also prepare and maintain a list of its SIUs. The list must be 

submitted to the Approval Authority with the original pretreatment program submission and then updated 

4-2 Introduction to the National Pretreatment Program 
Chapter 4. POTW Pretreatment Program Responsibilities 

annually as part of the annual POTW report [see 40 CFR 403.8(f)(2)(i)-(ii) and 40 CFR 403.12(i), 

respectively]. Although the General Pretreatment Regulations do not specify how a POTW is to identify 

its users, it is beneficial to conduct an initial in-depth survey and institute measures to update the list 

continuously. POTWs should ensure that they review the entire service area so they include relevant IUs 

outside the POTW’s jurisdictional boundaries. In such cases, it might be useful to solicit assistance from 

other jurisdictions in developing the list of potential dischargers. The types of resources that can be 

consulted in compiling and updating the master list are the following: 

 Water and sewer billing records 

 Applications for sewer service 

 Local telephone directories 

 Chamber of Commerce and local business directories 

 Business license records 

 POTW and wastewater collection personnel and field observations 

 Business associations 

 The Internet. 

Once the IUs are identified, the POTW must classify them to determine whether pretreatment 

standards and requirements apply to any of the facilities (40 CFR 403.8(f)(2)). Typically, the POTW 

develops and distributes an industrial waste survey (IWS) questionnaire to the identified IUs. The IWS 

questionnaire requests information regarding IU activities and the nature of wastes discharged. The 

POTW may opt to send a detailed IWS questionnaire or to conduct the survey in two phases, i.e., first 

sending a screener requesting basic information to eliminate obvious facilities and then sending a detailed 

IWS to those facilities with greater potential to be SIUs. The IWS must identify facilities that are subject 

to categorical standards (i.e., CIUs) or otherwise have the potential to affect the POTW (i.e., SIUs). 

The POTW must notify each SIU of its status and of all applicable pretreatment standards and 

requirements [see 40 CFR 403.8(f)(2)(iii)]. Therefore, a POTW’s IU inventory should include the name, 

location, classification, applicable standards, basis for limits imposed, volume of discharge, control 

mechanism status, compliance dates, and other special requirements for each IU. The completed IWS 

should provide most of the information required to develop the inventory, although some supplementary 

information might be required from other sources (such as the permit application or monitoring data). 

The IU inventory must be updated as needed (40 CFR 403.8(f)(2)(i)) and provided to the 

Approval Authority as part of the annual report requirement. (See the POTW Reports section in this 

chapter.) The ongoing task of maintaining a complete list of IUs requires the POTW to implement a 

system to track existing IU information, classification changes, and new user information. Some POTWs 

might proactively opt to institute a utility connect questionnaire program. Such types of forms are 

completed when a customer applies for new utility service, such as water, sewer, or electricity. 

IU PERMITS/CONTROL MECHANISMS

The General Pretreatment Regulations require that all IUs discharging to a POTW with an 

approved pretreatment program be controlled through permit, order, or similar means to ensure 

compliance with applicable pretreatment standards and requirements. The regulation at 40 CFR 

403.8(f)(1)(iii)(A and B) clarifies this requirement to specify that all SIUs must be issued an individual 

permit or equivalent individual control mechanism. Control mechanisms must be enforceable and contain, 

at a minimum, the following conditions: 

 A statement of duration (not to exceed 5 years) 

 A statement of nontransferabililty (unless outlined provisions are met) 

 Effluent limits, including BMPs, that are based on applicable standards 

Introduction to the National Pretreatment Program 4-3 
Chapter 4. POTW Pretreatment Program Responsibilities 

 Self-monitoring, sampling, reporting, notification, and record-keeping requirements 

 An identification of the pollutants to be monitored 

 The process for seeking a waiver for a pollutant neither present nor expected to be present 

in the discharge or a specific waived pollutant in the case of an individual control 

mechanism 

 Sampling location, sampling frequency, and sample type 

 A statement of applicable civil and criminal penalties 

 A schedule of compliance (where appropriate) 

 A requirement to control slug discharges, if determined by the POTW to be necessary. 

As a result of changes from the Streamlining Rule, and upon incorporation of appropriate 

authority and procedures into the approved program, a POTW may choose to issue a general permit to 

multiple IUs. All the facilities to be covered by a general permit must 

 Involve the same or substantially similar types of operations 

 Discharge the same types of wastes 

 Require the same effluent limitations 

 Require the same or similar monitoring 

 In the opinion of the POTW, be more appropriately controlled under a general permit than 

under individual permits. 

To be covered by a general permit, an SIU must file a written request for coverage that includes 

information found in 40 CFR 403.8(f)(1)(iii)(A)(2). A POTW may not control an SIU through a general 

permit in cases where the facility’s categorical pretreatment standards are production-based or expressed 

as mass of pollutant discharged per day, or where the facility’s limits are based on the combined 

wastestream formula (CWF) or net/gross calculations [40 CFR 403.6(e) and 403.15]. General permits 

must contain the minimum conditions required for individual permits, as listed earlier. 

EPA’s Industrial User Permitting Guidance Manual (Draft) details procedures for drafting IU 

discharge permits. SIU permits are site-specific and tailored to the unique circumstances of the IU. Permit 

conditions should contain clear and explicit requirements for the permittee, including using terms such as

must and must not, where appropriate, in lieu of vague terms such as recommend, may, and should. The 

POTW should document its decision-making process when developing permits to ensure defensibility and 

enforceability. Adherence to sound, documented procedures will help prevent claims by the permittee that 

the POTW’s actions were arbitrary or capricious. Whether developing or reissuing a permit, the 

permitting process usually consists of three phases: 

 Phase I—Collection and verification of information 

 Phase II—Data interpretation and fact sheet development 

 Phase III—Permit development and issuance. 

As part of Phase I, POTWs may review and verify information in the permit application, perform 

an inspection of the IU for confirmation of facts, tally data, and potentially sample and analyze the IU’s 

wastestream. Knowledgeable POTW personnel, effective communication, and SIU cooperation are 

essential to collecting complete and accurate information. 

Phase II could require the POTW to interpret data and other information and document the permit 

decision-making rationale, preferably in a permit fact sheet. Although the contents of the fact sheets will 

4-4 Introduction to the National Pretreatment Program 
Chapter 4. POTW Pretreatment Program Responsibilities 

vary by permittee, they need to provide a 

justification for all permitting decisions. The 

typical components of a fact sheet are listed in 

figure 4-2. Completed fact sheets should be 

included in each IU file and provided to the 

permittee to underscore the soundness of 

permitting decisions. 

For CIUs 

 The basis for the categorical determination(s) 

 The identity and flow volume of all wastestreams 

generated and discharged to the POTW, classified 

accordingly (i.e., regulated, unregulated, or dilution) 

 Calculations, if needed, for applying CWF, flow-weighted 

average, and production-based standards 

 Basis of selecting any values used in calculations 

 Data uses and/or justification for estimates used to 

determine categorical limitations 

For SIUs/CIUs 

 The basis for limits imposed for all parameters 

(categorical, local limits, and such) 

 The rationale for any compliance schedules, special plans 

required, and special conditions 

 The basis for monitoring and reporting frequencies 

Figure 4-2. Components of the permit fact sheet.

After all permitting decisions have been 

made, the POTW incorporates them into a permit 

(Phase III). The POTW provides the draft permit, 

signed by the specified POTW official, to the 

permittee for comment; after comments are 

addressed, the POTW issues a final permit to the 

IU. Although the POTW can easily address and 

resolve many comments, occasionally a 

resolution must be reached through a formal 

adjudicatory hearing, at which both the permittee 

and POTW present their cases to a third party 

(e.g., permit appeal). 

Many POTWs also control contributions from non-SIUs using various means, such as general 

permits issued to an entire industrial sector. These types of control mechanisms could require compliance 

with BMPs in addition to or in place of specific pollutant limitations. For example, 

 Grease trap maintenance and record-keeping requirements for food establishments 

 Maintenance and record-keeping requirements for photo processors' silver-reclamation 

units 

 Mercury recovery by hospitals and dentists. 

Industrial sector general permitting programs are common where a real or potential POTW 

problem is linked to a pollutant discharged (e.g., collection system blockages caused by food 

establishments discharging excess oil and grease). POTWs should also have authority to enforce their 

SUO or rules or regulations against non-SIUs without the need for any type of individual control 

mechanism. Likewise, POTWs should have the authority to require non-SIUs to comply with 

pretreatment standards and requirements in their local regulations and take appropriate actions against IUs 

when noncompliance is identified. 

INSPECTIONS

POTWs are required to inspect all SIUs at least once a year pursuant to 40 CFR 403.8(f)(2)(v). 

Although EPA regulations establish a minimum frequency for inspections, additional inspections by the 

POTW might be necessary depending on issues such as the variability of an SIU’s effluent, the effect of 

the SIU’s discharge on the POTW, and the facility’s compliance history. Inspection considerations 

(figure 4-3) hinge on the type of inspection performed (e.g., scheduled, unscheduled, or on-demand). 

EPA’s 1994 Industrial User Inspection and Sampling Manual for POTWs provides a detailed reference 

for inspection procedures and protocols. 

The Streamlining Rule revisions allow POTWs to classify some CIUs as MTCIUs. MTCIUs are 

still SIUs, but if they meet the conditions in 40 CFR 403.12(e)(3), they qualify for reduced reporting and 

oversight. POTWs are required to inspect MTCIUs at least once every 2 years. If an MTCIU no longer 

Introduction to the National Pretreatment Program 4-5 
Chapter 4. POTW Pretreatment Program Responsibilities 

meets the conditions in 40 CFR 403.12(e)(3), the POTW must immediately begin inspecting the CIU at 

least once a year (the minimum frequency for inspecting an SIU). 

 Provide current data on the IU. 

 Confirm or determine the IU’s compliance status. 

 Determine completeness and accuracy of the IU's performance/compliance records. 

 Assess the adequacy of the IU's self-monitoring and reporting requirements. 

 Assess the adequacy of monitoring locations and IU's sampling techniques. 

 Assess the adequacy of imposed limitations and pollutants of concern. 

 Develop a rapport with the IU. 

 Evaluate operation and maintenance and overall performance of an IU's pretreatment system. 

 Assess the potential for spills and slug loadings. 

 Evaluate the effectiveness of slug control plan. 

 Reveal issues requiring action 

 Identify noncompliance needing resolution 

 Suggest pollution prevention opportunities 

 Collect samples 

 Obtain data to support enforcement actions 

Figure 4-3. Inspection considerations. 

Scheduled inspections are useful when the POTW wants to gather specific information from the 

facility that necessitates meeting with specific SIU contacts. However, on-demand inspections or 

unscheduled inspections might more accurately reflect SIU compliance status because scheduled 

inspections sometimes interrupt normal operations. (For example, the production schedule might be 

altered as a result of preparatory work undertaken by the SIU.) On-demand inspections are nonroutine and 

occur in response to a concern such as POTW collection problems downstream from an IU, elevated 

enforcement actions against an IU, suspicious IU behavior, or an informer’s complaint. 

Routine POTW inspections of SIUs typically consist of three activities––preparation, on-site 

assessment, and follow-up. 

 Preparation. POTW personnel should review POTW records for an SIU to be inspected to 

familiarize themselves with the facility. The information reviewed might include compliance 

status, compliance schedule activities, reports and plans, upcoming report and plan due dates, 

enforcement activities, permit applications, waste surveys, previous inspection summaries, 

categorical regulations, water use/billing records, and POTW collection system maps. POTW 

personnel should also be familiar with any specific issues and concerns regarding the 

POTW’s treatment plant or collection system potentially caused by the SIU's discharge. 

 On-site assessment. POTW personnel typically discuss IU operations with IU contacts and 

walk through the facility to update IU information regarding contacts, processes, production 

rates, pretreatment, and other waste management activities; review records that the IU is 

required to keep; visually verify the need for a slug control plan; and review pretreatment 

system maintenance, categorical standards applicable to processes employed, metering and 

sampling equipment, sampling procedures, chemicals used, processes employed, 

management practices, containment structures, locations of floor drains, and the like. Many 

POTWs have developed a standard inspection questionnaire to facilitate the interview process 

and promote consistency during the inspection. 

4-6 Introduction to the National Pretreatment Program 
Chapter 4. POTW Pretreatment Program Responsibilities 

 Follow-up. The POTW should prepare an inspection report as soon as possible after the 

inspector returns to the office. Unanswered questions, required permit modifications, or 

necessary enforcement actions should be processed in a timely manner. 

Nonroutine inspections such as on-demand inspections might not encompass all the activities and 

steps specified above. Like routine inspections, however, such activities should provide the POTW an 

opportunity to collect samples of the IU’s discharge. 

POTWs must also evaluate whether each SIU needs a plan or other action to control slug 

discharges. (A slug discharge is a discharge of a nonroutine, episodic nature, including an accidental spill 

or noncustomary batch discharge.) To accurately evaluate the slug potential, POTWs likely will have to 

examine the SIU during its normal operating conditions. If undetected, slug discharges can have serious 

effects on the POTW. EPA’s 1991 Control of Slug Loadings to POTWs Guidance Manual provides 

procedures for developing, implementing, and reviewing slug control plans. Additional information on 

slug control plans is included in chapter 5 of this manual. 

SAMPLING

With the exception of MTCIUs and NSCIUs, the General Pretreatment Regulations require 

POTWs to monitor each SIU at least annually and each SIU to self-monitor at least semiannually (once 

every six months). The POTW may choose to monitor in lieu of requiring the IU to perform the selfmonitoring. If sampling conducted by the IU indicates a violation, the IU must repeat the sampling and 

submit analytical results within 30 days after becoming aware of the violation. If the IU performed the 

initial sampling, the IU must notify the POTW within 24 hours of becoming aware of the violation in 

addition to performing the follow-up sampling and analysis. In cases where the POTW has assumed 

responsibility for sampling in lieu of the SIU, the POTW must repeat the sampling and analysis. An 

exception to that requirement is made if the POTW performs the sampling at the IU at a frequency of at 

least once per month or if the POTW performs sampling at the IU between the time of the initial sampling 

and the receipt of the results of that sampling. For a discussion on self-monitoring, see chapter 5. 

For MTCIUs, the POTW is required to conduct sampling at least once every 2 years. For 

NSCIUs, the POTW is required to evaluate, at least every 2 years, whether the IU continues to meet the 

criteria that qualify it as an NSCIU. Where the POTW has authorized the SIU to forego sampling of a 

pollutant regulated by a categorical pretreatment standard (under 40 CFR 403.12(e)(2)), the POTW must 

sample for the waived pollutant(s) at least once during the term of the CIU’s control mechanism 

(maximum duration of 5 years). 

As with inspections, the POTW should assess site-specific issues, such as SIU effluent variability, 

the effect of the effluent on the POTW, and the SIU’s compliance history, to determine appropriate 

sampling frequencies (i.e., if more or less frequent monitoring is necessary). A more detailed discussion 

of IU monitoring requirements is provided in chapter 5. For more detailed information on sampling 

frequencies, refer to EPA’s 1994 Industrial User Inspection and Sampling Manual for POTWs. 

Sampling is the most appropriate method for verifying compliance with pretreatment standards. 

The POTW designates the monitoring location(s), which must be selected such that compliance with 

permitted discharge limits can be determined. Where possible, the POTW should not designate 

monitoring locations that are confined spaces, are difficult to access, or make it difficult to place the 

automated sampling equipment. Monitoring locations should 

 Be appropriate for wastestream conditions 

 Be representative of the discharge 

 Have no bypass capabilities 

Introduction to the National Pretreatment Program 4-7 
Chapter 4. POTW Pretreatment Program Responsibilities 

 Allow for unrestricted access at all times. 

Grab samples must be used for pH, cyanide, total phenols, oil and grease, sulfide, and volatile 

organic compounds. For all other pollutants, 24-hour composite samples must be obtained through flowproportional composite sampling techniques, unless the POTW authorizes time-proportional composite 

sampling or grab sampling. Where the POTW authorizes time-proportional composite sampling or grab 

sampling, (1) the samples must be representative of the discharge, and (2) the justification for the decision 

to allow the alternative sampling must be documented in the IU’s file for that facility or facilities. Using 

protocols (including appropriate preservation) specified in 40 CFR Part 136 and appropriate EPA 

guidance, multiple grab samples collected during a 24-hour period may be composited before the analysis 

as follows: for cyanide, total phenols, and sulfides, the samples may be composited in the laboratory or in 

the field; for volatile organics and oil and grease, the samples may be composited in the laboratory. The 

POTW may authorize, as appropriate, composite samples for other parameters unaffected by the 

compositing procedures as documented in approved EPA methodologies. 

Adherence to proper sample collection and handling protocols, 40 CFR Part 136-approved 

analytical methodologies, and record-keeping requirements [40 CFR 403.12(o)(1)] (see figure 4-4) can be 

verified by reviewing field measurement records, chain-of-custody forms, and lab reports. Field 

Parameter 

Sample 

type Container Preservative Holding time 

pH Grab Polyethylene or glass N/A Analyze 

immediately 

BOD Composite Polyethylene or glass Chilled to < 6 °C 48 hours 

TSS Composite Polyethylene or glass Chilled to < 6 °C 7 days 

NH3 as N Composite Polyethylene or glass Chilled to < 6 °C, H2SO4

to pH < 2 28 days 

Oil and grease Grab Glass Chilled to < 6 °C, HCl or 

H2SO4 to pH < 2 28 days 

Cyanide, total Grab Polyethylene or glass 

Chilled to < 6 °C, NaOH 

to a pH > 12, and 0.6 g of 

ascorbic acid if residual 

chlorine is present 

14 days 

Metals (total) Composite Polyethylene or glass HNO3 to pH < 2 6 months 

Chromium, 

hexavalent Composite Polyethylene, fluoropolymer, or glass Chilled to < 6 °C 28 days 

Boron Composite 

Polyethylene, 

fluoropolymer, or 

Quartz 

HNO3 6 months 

Mercury Composite Polyethylene, 

fluoropolymer, or glass HNO3 28 days 

624 (volatiles 

organics) Grab 

Amber glass, w/Teflon 

septum lid and zero 

headspace 

Chilled to < 6 °C 

(additional laboratory 

preservation required) 

7 or 14 days, 

depending on 

specific organic 

625 (semivolatile 

organics) Composite Amber glass w/Teflonlined lid 

Chilled to < 6 °C 

(additional laboratory 

preservation required) 

7 days for sample 

prep; 40 days for 

extract 

Figure 4-4. Suggested sample collection techniques. 

4-8 Introduction to the National Pretreatment Program 
Chapter 4. POTW Pretreatment Program Responsibilities 

measurement records may require information regarding sample location, condition of and programmed 

settings for sampling equipment, wastewater meter readings, and information for such parameters as pH 

and temperature, which require analysis in the field. Chain-of-custody forms are a link between field 

personnel and the laboratory, and they contain information regarding sample matrix, type, and handling. 

Lab reports should contain the minimum information specified in 40 CFR 403.12(o)(1)(ii-iv) and any 

additional information necessary to demonstrate compliance with 40 CFR Part 136 requirements (e.g., 

analytical methodology, sample preparation date and time, time of analysis). Using standardized forms 

that prompt recording the information necessary to demonstrate compliance with applicable requirements 

helps to ensure that data can be used as admissible evidence in enforcement proceedings or in judicial 

actions. 

CONTROL AUTHORITY ENFORCEMENT

In addition to requirements for permitting, sampling, and inspecting IUs, the General 

Pretreatment Regulations require POTWs to review IU reports and plans and to respond to instances of IU 

noncompliance in a timely, fair, and consistent manner. Enforcement of pretreatment requirements is a 

critical element of the National Pretreatment Program. In the early years of the Program, EPA became 

aware that in certain instances extenuating circumstances could prevent POTWs from taking adequate 

enforcement steps. For example, political and economic pressures from local officials might keep POTW 

personnel from taking appropriate actions. After that was identified as a major concern, EPA promulgated 

regulations in 1990 (55 FR 30082) that require all POTWs with approved pretreatment programs to adopt 

and implement an enforcement response plan (ERP). The ERP regulations at 40 CFR 403.8(f)(5) establish 

a framework for POTWs to formalize procedures for investigating and responding to instances of IU 

noncompliance. The purpose of developing and following an approved ERP is so that POTWs enforce 

against IUs objectively, consistently, and equitably and thereby minimize any potential outside pressures 

to overlook potential violations. 

To evaluate IU compliance, POTWs must first identify the applicable requirements for each IU. 

In general, IU reports (discussed in chapter 5) and POTW monitoring activities are the basis for POTW 

evaluation of IU compliance. Discharge permit limit exceedances, discrepancies, deficiencies, and 

lateness are all violations that must be resolved. 

To ensure that enforcement response is appropriate and that the POTW’s actions are not arbitrary 

or capricious, EPA strongly recommends that the POTW include an enforcement response guide (ERG) 

as part of the approved ERP. The ERG typically identifies responsible POTW officials, a general time 

frame for actions, expected IU responses, and potential escalated actions based on the following: 

 Nature of the violation 

– Pretreatment standards 

– Reporting (late or deficient) 

– Compliance schedules 

 Magnitude of the violation 

 Duration of the violation 

 Frequency of the violation (isolated or recurring) 

 (Potential) effect of the violation (e.g., interference, pass through, or POTW worker safety) 

 Economic benefit gained by the violator 

 Attitude of the violator. 

Figure 4-5 illustrates the types of questions that dictate whether an ERG is adequate. Factors that 

the POTW should consider in determining appropriate enforcement responses to noncompliance events 

are discussed in detail in EPA's 1989 Guidance for Developing Control Authority Enforcement Response 

Plans. 

Introduction to the National Pretreatment Program 4-9 
Chapter 4. POTW Pretreatment Program Responsibilities 

Q: Is a POTW response required for all violations that were identified? 

Q: Is the IU notified by the POTW when a violation is found? 

Q: Is the IU required to respond to each violation with an explanation and, as appropriate, a plan to correct the 

violation within a specified period? 

Q: Where noncompliance continues or the IU response is inadequate, does the POTW's response become more 

formal and are commitments (or schedules, as appropriate) for compliance established in an enforceable 

document? 

Q: Is the enforcement response selected related to the seriousness of the violation? 

Q: Where the violation constitutes SNC, and is ongoing, is the minimum response an administrative order? 

Figure 4-5. How complete is your ERG? 

Although POTWs should strive for consistent compliance by all permitted IUs, the General 

Pretreatment Regulations establish criteria for SNC for violations that would have a potential for greater 

environmental impact. SNC is defined in 40 CFR 403.8(f)(2)(viii) and depicted in figure 4-6. A decision 

to seek formal enforcement is generally triggered by an unresolved instance of SNC, failure to achieve 

compliance in a specified period through less formal means, or the advice of legal counsel. SNC 

evaluations are to be conducted in 6-month increments. The names of IUs found to be in SNC must be 

published in a newspaper(s) of general circulation that provides meaningful public notice within the 

jurisdiction(s) served by the POTW; refer to the Public Participation section in this chapter. 

An IU is in SNC if its violation meets one or more of the following criteria (40 CFR 

403.8(f)(2)(viii)): 

(A) Chronic violations of wastewater discharge limits, defined here as those in which 66 percent or more of all the 

measurements taken during a 6-month period exceed (by any magnitude) a numeric pretreatment standard or requirement, 

including instantaneous limits, as defined by 40 CFR 403.3(l) 

(B) Technical Review Criteria (TRC) violations, defined here as those in which 33 percent or more of all of the measurements for 

each pollutant parameter taken during a 6-month period equal or exceed the product of the numeric pretreatment standard 

or requirement including instantaneous limits, as defined by 40 CFR 403.3(l) multiplied by the applicable TRC (TRC = 1.4 for 

BOD5, TSS, fats, oil, and grease; and 1.2 for all other pollutants except pH) 

(C) Any other violation of a pretreatment Standard or Requirement as defined at 40 CFR 403.3(1) (daily maximum, long-term 

average, instantaneous limit, or narrative standard) that the POTW determines has caused, alone or in combination with 

other discharges, interference or pass through (including endangering the health of POTW personnel or the general public) 

(D) Any discharge of a pollutant that has caused imminent endangerment to human health, welfare or to the environment or has 

resulted in the POTW’s exercise of its emergency authority under 40 CFR 403.8(f)(1)(vi)(B) of this section to halt or prevent 

such a discharge 

(E) Failure to meet, within 90 days after the schedule date, a compliance schedule milestone contained in a local control 

mechanism or enforcement order for starting construction, completing construction, or attaining final compliance 

(F) Failure to provide, within 45 days after the due date, required reports such as baseline monitoring reports, 90-day 

compliance reports, periodic self-monitoring reports, and reports on compliance with compliance schedules 

(G) Failure to accurately report noncompliance 

(H) Any other violation or group of violations, which could include a violation of BMPs, that the POTW determines will adversely 

affect the operation or implementation of the local pretreatment program 

Figure 4-6. Definition of SNC. 

Formal enforcement needs to be supported by well-documented records of the violations and of 

any prior efforts by the POTW to obtain compliance. Where effluent limitations have been exceeded, 

records should be reviewed to verify compliance with 40 CFR Part 136 test methods. If the IU has 

received conflicting information from the POTW regarding its compliance status, its status should be 

clarified in writing. The POTW might wish to consider a show cause meeting with the IU before 

beginning formal enforcement action because the regulations do allow, in certain instances, an affirmative 

defense for violations. 

4-10 Introduction to the National Pretreatment Program 
Chapter 4. POTW Pretreatment Program Responsibilities 

The range of enforcement mechanisms available to a POTW depends on the specific legal 

authorities provided by city, county, and state law. The mechanisms could range from a simple telephone 

call to suits seeking significant criminal penalties. Common enforcement mechanisms include the 

following: 

 Informal notice to IU. This notice could consist of a telephone call or a reminder letter to 

an appropriate IU official to notify him or her of a minor violation and to seek an 

explanation. Such an informal notice can be used to correct minor instances of 

noncompliance. 

 Informal meetings. Informal meetings can be used to obtain an IU's commitment to 

comply with its pretreatment obligations or to inform the IU of stronger enforcement 

mechanisms available for unresolved or continued noncompliance. 

 Warning letter or Notice of Violation (NOV). This written notice to the IU in response to 

a violation of pretreatment standards or requirements should request an explanation of the 

noncompliance and measures that will be taken to eliminate future violations. 

 Administrative orders and compliance schedules. These may require an IU to show cause

to the POTW as to why formal enforcement action should not be taken or sewer service 

discontinued, or what actions will be taken to comply with pretreatment standards or 

requirements. Such orders may be negotiated (i.e., Consent Order) or issued at the 

reasonable discretion of the POTW (i.e., Compliance Order). For more egregious or 

serious violations, the POTW may issue a Cease and Desist Order. 

 Administrative fines. POTWs may assess fines against IUs for violations. The fines are 

intended to recapture partial or full economic benefit for the noncompliance and to deter 

future violations. 

NOTE: Surcharges are not penalties or fines. Surcharges are intended to recoup the cost of 

treatment of (compatible) wastes by the POTW, and they must not be used to allow 

discharges of toxic pollutants that cause interference or pass through. 

 Civil suits. Civil suits are a formal process of filing lawsuits against IUs to correct 

violations and to obtain penalties for violations. Civil penalty amounts are generally 

established through state or municipal laws. However, 40 CFR 403.8(f)(1)(vii) requires 

that POTWs have the legal authority to seek or assess civil or criminal penalties of at least 

$1,000 per day for each violation. A civil suit for injunctive relief may be used when the 

IU is unlikely to successfully execute the steps that the POTW believes are necessary to 

achieve or maintain compliance, when the violation is serious enough to warrant court 

action to deter future similar violations, or when the danger presented by an IU’s lengthy 

negotiation of a settlement is intolerable. 

 Criminal prosecution. This type of enforcement is a formal judicial process in which 

sufficient admissible evidence exists to prove beyond a reasonable doubt that a person has 

willfully or negligently violated pretreatment standards or that a person has knowingly 

made a false statement regarding any report, application, record, or other document 

required by the General Pretreatment Regulations. As noted earlier, POTWs must have the 

legal authority to seek or assess civil or criminal penalties of at least $1,000 per day for 

each violation. Examples of criminal violations include falsifying data and tampering with 

sampling results or equipment. 

 Termination of service (revocation of permit). POTWs may pursue permit revocation to 

immediately halt an actual or threatened discharge to the POTW that could represent an 

Introduction to the National Pretreatment Program 4-11 
Chapter 4. POTW Pretreatment Program Responsibilities 

4-12 Introduction to the National Pretreatment Program 

endangerment to the public health, the environment, or the POTW. This remedy may also 

be used to bring recalcitrant IUs into compliance. 

Regardless of the response taken, the POTW should document and track all contact, notices, and 

meetings with IUs and any IU responses. POTW actions and IU responses (or lack thereof) should be 

documented, including a record of any direct contact with the IU to attempt to resolve the noncompliance. 

POTWs should take timely and effective enforcement actions against violators. 

PROGRAM MANAGEMENT AND 

RECORD KEEPING

POTWs must maintain general program files 

that document program development and 

implementation activities that are not IU-specific 

(figure 4-7). Furthermore, pretreatment programs are 

required to maintain local limits records during at least 

the effective dates of the developed local limits and for 

3 years after. All information should be filed in an 

orderly manner and be readily accessible for inspection 

and copying by EPA and state representatives or the 

public. The pretreatment regulations specify that all 

information submitted to the POTW or state must be 

available to the public without restriction, except for 

confidential business information (40 CFR 403.14). 

The POTW is required to maintain records 

resulting from monitoring in a readily accessible 

manner for at least 3 years (40 CFR 403.12(o)). 

Although the means for maintaining files is usually at 

the discretion of the POTW, all required pretreatment 

activities must be recorded and the documents 

maintained. Types of records submitted by and 

pertaining to IUs are summarized in figure 4-8.14

POTWs must also maintain the following 

documentation, when applicable: 

 Equivalent limits [40 CFR 403.6(c)(6)].

If the POTW allows the conversion of 

the mass limits of the categorical 

pretreatment standards at 40 CFR Parts 

414, 419, and 455 to concentration-based 

limits, the POTW should document that 

dilution is not being substituted for 

treatment. 

 Equivalent limits [40 CFR 403.6(c)(7)].

If the POTW allows equivalent 

concentration- or mass-based limits, the POTW should document how the equivalent 

limits were derived and make this information publicly available. 

 

14 Descriptions of the documents required to be submitted by IUs are provided in chapter 5. 

 Legal authority (e.g., SUO) 

 Program procedures 

 Program approval and modifications 

 List of SIUs 

 Copy of POTW NPDES permit(s) 

 Local limits development 

 ERP 

 Correspondence to and from EPA/state 

 Annual reports to the Approval Authority 

 Public notices 

 Funding and resource changes 

 Applicable federal and state regulations 

 IU compliance and permitting records 

 IWS results 

Figure 4-7. Types of POTW records 

retained. 

 Industrial waste questionnaires 

 Permit applications, permits and fact sheets 

 Inspection reports 

 IU reports 

 Monitoring data (including laboratory reports) 

 Required plans (e.g., slug control, sludge 

management, pollution prevention) 

 Enforcement activities 

 All correspondence to and from the IU 

 Phone logs and meeting summaries 

Figure 4-8. Types of IU records retained 

by POTW. 
Chapter 4. POTW Pretreatment Program Responsibilities 

 General control mechanism [40 CFR 403.8(f)(1)(iii)(A)(2)]. A copy of the general 

control mechanism, documentation to support the POTW’s determination that a specific 

SIU meets the criteria necessary to qualify for a general permit, and a copy of the IU’s 

written request for coverage must be maintained for 3 years after the expiration of the 

general control mechanism. 

 Monitoring waiver for pollutant not present [40 CFR 403.12(e)(2)(iv)]. The reasons 

supporting the monitoring waiver and any information submitted by the IU in its request 

for the waiver must be maintained for 3 years after expiration of the waiver. 

 MTCIU [40 CFR 403.12(e)(3)(v)]. Documentation to support the POTW’s determination 

that a specific IU qualifies for reduced reporting requirements must be maintained for 3 

years after the expiration of the term of the control mechanism in which the middle-tier 

requirements were applied. 

 Alternative sampling method [40 CFR 403.12(g)(3)]. Documentation on the justification 

to allow time-proportional composite sampling or grab sampling in lieu of flowproportional composite sampling must be maintained. 

 BMPs [40 CFR 403.12(o)]. Documentation associated with BMP compliance must be 

maintained for 3 years. 

A computerized data management system can assist in tracking due dates, submissions, 

deficiencies, notifications, and the like and in calculating effluent limitation noncompliance. Similarly, 

many POTWs use standardized forms (e.g., inspection questionnaires, chains of custody, and field 

measurement records) and procedures (e.g., sampling and periodic compliance report reviews) to promote 

the consistency and organization of program data. 

PUBLIC PARTICIPATION

One of the goals of CWA section 101(e) is public participation in the development, revision, and 

enforcement of any regulation, standard, effluent limitation, plan, or program established by EPA or any 

state. The General Pretreatment Regulations encourage public participation by requiring public notices or 

hearings for program approval, removal credits, program modifications, local limits development and 

modifications, and IUs in SNC. 

POTW pretreatment program approval requests require the Approval Authority to publish a 

notice (including a notice for a public hearing) in a newspaper of general circulation within the 

jurisdiction served by the POTW. All comments regarding the request and any request for a public 

hearing must be filed with the Approval Authority within the specified comment period, which is 

typically 30 days. The Approval Authority takes into consideration all comments received when deciding 

to approve or deny the submission. The decision is then provided to the POTW and other interested 

parties and published in the newspaper; all comments received must be available to the public for 

inspection and copying. 

After a local pretreatment program is approved, the requirement to implement the program is 

incorporated into the NPDES permit and the POTW must implement that program as approved. Before a 

POTW may implement a significant change in its pretreatment program operation, it must initiate a 

program modification. 

For substantial program modifications (figure 4-9), the POTW is required to notify the Approval 

Authority of its desire to modify its program and the basis for the change. Such changes become effective 

upon approval. Approval Authorities (or POTWs) are required to provide public notice of the request for 

Introduction to the National Pretreatment Program 4-13 
Chapter 4. POTW Pretreatment Program Responsibilities 

a modification, but they are not required to provide public notice of the decision if no comments are 

received and the request is approved without changes (40 CFR 403.11 and 403.18(c)(3)&(4)). After EPA 

amends the General Pretreatment Regulations, a POTW will often be required to modify its approved 

program to ensure that the legal authority and program procedures provide for implementation of those 

requirements. That is true even where the amendments to the General Pretreatment Regulations allow for 

relaxed requirements for the POTW or its IUs. Failure to submit program modifications before 

implementation in such cases could result in the POTW’s violating its NPDES permit because 

implementation of the approved program is usually a requirement of the POTW’s NPDES permit. 

Nonsubstantial modifications must also be submitted to the Approval Authority for review and 

approval, but these changes do not require public notice. Unlike substantial modifications, nonsubstantial 

modifications become effective 45 days after submission unless the Approval Authority notifies the 

POTW otherwise. 

The POTW also must annually publish—in a newspaper(s) of general circulation that provides 

meaningful public notice within the jurisdiction(s) served by the POTW—a list of IUs that were in SNC 

at any time during the previous 12 months. 

1. Modifications that relax POTW legal authorities [as described in 40 CFR 403.8(f)(1)], except for modifications that 

directly reflect a revision to 40 CFR Part 403, and are reported pursuant to 40 CFR 403.18(d) 

2. Modifications that relax local limits, except for modifications to local limits for pH and reallocations of the MAIL of a 

pollutant that do not increase the total industrial loadings for a pollutant, and that are reported pursuant to 40 CFR 

403.18(d) 

3. Changes to a POTW's control mechanism, as described in 40 CFR 403.8(f)(1)(iii) 

4. A decrease in the frequency of self-monitoring or reporting required of IUs 

5. A decrease in the frequency of IU inspections or sampling by the POTW 

6. Changes to the POTW's confidentiality procedures 

7. Other modifications designated as substantial modifications by the Approval Authority because the modification could 

have a significant effect on the operation of the POTW's pretreatment program; could result in an increase in pollutant 

loadings at the POTW; or could result in less stringent requirements being imposed on the POTW’s IUs 

Figure 4-9. Substantial modifications of POTW pretreatment programs (40 CFR 403.18).

POTW REPORTING

In accordance with 40 CFR 403.12(i), POTWs are required to submit annual reports to the 

Approval Authority documenting program status and activities performed during the previous year. At a 

minimum, the reports must contain the following information: 

 A list of all the POTW's IUs, including names, addresses, pretreatment standards 

applicable to each user, a brief explanation of deletions, and a list of additions (with the 

aforementioned information) keyed to a previously submitted list. The list must also 

identify IUs that are designated as MTCIUs and must identify which IUs are NSCIUs 

 A summary of the status of IU compliance during the reporting period 

 A summary of compliance and enforcement activities (including inspections) conducted by 

the POTW during the reporting period 

 A summary of changes to the POTW's pretreatment program that have not been previously 

reported to the Approval Authority 

 Any other relevant information requested by the Approval Authority. 

4-14 Introduction to the National Pretreatment Program 
Chapter 4. POTW Pretreatment Program Responsibilities 

Introduction to the National Pretreatment Program 4-15 

The first annual report is due within one year after program approval; reports are due at least 

annually thereafter. Approval Authorities may require additional information or require that the reports be 

submitted in a specific format or at an increased frequency (e.g., semiannually). 

The reports must be signed by a principal executive officer, ranking elected official, or other duly 

authorized employee. The duly authorized employee must be an individual or position having 

responsibility for the overall operation of the facility or the pretreatment program. This authorization must 

be made in writing by the principal executive officer or ranking elected official and submitted to the 

Approval Authority before or together with the report being submitted. 

In addition, 40 CFR 122.42(b) requires POTWs to notify the director of new pollutants or 

changes in discharge. All POTWs are required to provide adequate notice to the director of the following: 

(1) any new introduction of pollutants into the POTW from an indirect discharger that would be subject to 

section 301 or 306 of the CWA if it were directly discharging those pollutants and (2) any substantial 

change in the volume or character of pollutants being introduced into the POTW by a source introducing 

pollutants into the POTW at the time of issuance of the permit. 

APPROVAL AUTHORITY ENFORCEMENT

POTW or IU noncompliance can result in the Approval Authority’s enforcing directly against the 

IU, the POTW, or both. An Approval Authority routinely reviews the overall performance of a POTW in 

monitoring IUs, identifying violations, and enforcing regulations. Performance will be evaluated on the 

basis of POTW self-monitoring data, written ERPs, audits, inspections, and pretreatment program reports 

(including IU self-monitoring reports and other data). Therefore, it is essential for POTWs to effectively 

manage program information to demonstrate proper implementation. 

CWA section 505 allows citizens to file suit against a POTW that has failed to implement its 

approved pretreatment program as required by its NPDES permit. The POTW may be fined, as well as 

subject to injunctive relief. Citizens may also file suit against IUs that have failed to comply with 

pretreatment standards and requirements. 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

3. 

CHAPTER 5. 

INDUSTRIAL USER PRETREATMENT 

PROGRAM RESPONSIBILITIES

Chapter 5. Applicable EPA Guidance 

Guidance Manual for Implementing Total Toxic Organics (TTO) Pretreatment Standards (EPA September 1985) 

Guidance Manual for the Identification of Hazardous Wastes Delivered to Publicly Owned Treatment Works by Truck, 

Rail, or Dedicated Pipe (EPA July 1987) 

Guidance Manual for the Use of Production-Based Pretreatment Standards and the Combined Wastestream Formula

(EPA September 1985) 

Industrial User Inspection and Sampling Manual for POTWs (EPA 831-B-94-001) 

RCRA Information on Hazardous Wastes for Publicly Owned Treatment Works (EPA September 1985) 

Industry-Specific Guides 

Aluminum, Copper, and Nonferrous Metals Forming and Metal Powders Pretreatment Standards: A Guidance 

Manual (EPA 800B89001) 

Guidance Manual for Battery Manufacturing Pretreatment Standards (EPA August 1987) 

Guidance Manual for Electroplating and Metal Finishing Pretreatment Standard (EPA-440/1-84/091g) 

Guidance Manual for Iron and Steel Manufacturing Pretreatment Standards (EPA September 1985) 

Guidance Manual for Leather Tanning and Finishing Pretreatment Standards (EPA 833B86101) 

Guidance Manual for Pulp, Paper, and Paperboard and Builders’ Paper and Board Mills Pretreatment Standards

(EPA July 1984) 

IUs are required to comply with all applicable federal, state, and local pretreatment standards and 

requirements. Demonstration of compliance requires certain IUs to submit reports, self-monitor, and 

maintain records. Summaries of the federal reporting and notification requirements are provided in 

attachments 5-1 and 5-2; details of each of these requirements are discussed below. POTW personnel 

must also be aware of, and comply with, all relevant state and local pretreatment requirements. 

REPORTING REQUIREMENTS

National minimum pretreatment program reporting requirements for IUs are specified in 40 CFR 

403.12. Because POTWs are responsible for communicating applicable standards and requirements to IUs 

and for receiving and analyzing reports, it is essential for POTW personnel to understand the IU reporting 

requirements in the General Pretreatment Regulations. Those requirements are summarized below. In 

cases where the POTW itself collects all the information required for a specific report, including flow 

data, the IU is not required to submit that report. 

Introduction to the National Pretreatment Program 5-1 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

Categorical Industrial User Reporting Requirements 

Baseline Monitoring Report [40 CFR 403.12(b)] 

Each IU that is subject to a categorical pretreatment standard (identified as a CIU) is required to 

self-monitor and submit a baseline monitoring report (BMR) within 180 days after the effective date of 

the standard. If a category determination has been requested, the BMR is not due until 180 days after a 

final administrative decision has been made concerning the industry's inclusion in the category. The BMR 

must contain the following information: 

 The name and address of the facility and name(s) of the operator and owners. 

 A list of all environmental control permits held by or for the facility.

 A description of operations, including the average rate of production, applicable North 

American Industry Classification System (NAICS) codes, schematic process diagrams, and 

points of discharge to the POTW from regulated processes. 

 Flow measurements (average daily and maximum daily) for regulated process 

wastestreams and nonregulated wastestreams, where necessary. 

 Categorical pretreatment standards applicable to each regulated process. In cases where the 

standard requires compliance with a BMP or pollution-prevention alternative, the CIU 

must submit documentation as required by the POTW or the applicable standards to 

determine compliance with the standard. 

 Sampling and analysis results (daily maximum, average concentration, and mass (where 

applicable). 

 Time, date, and place of sampling; methods of analysis; certification that sampling and 

analysis are representative of normal work cycles and expected pollutant discharges to the 

POTW. 

 Certification by a qualified professional, reviewed by an authorized representative of the 

CIU, of whether applicable pretreatment standards are being met on a consistent basis and, 

if not, a description of the additional operation and maintenance or pretreatment facilities 

that are needed to comply with the standards. In cases where the POTW performs the 

required sampling and analysis in lieu of the IU, the IU will not be required to submit the 

compliance certification. 

 Schedule for providing the additional operation and maintenance or pretreatment needed 

by the IU to comply with the applicable pretreatment standards. 

In addition to the certification noted above, BMRs must be signed and certified by an authorized 

representative of the CIU as detailed in 40 CFR 403.12(l) and as described later in this chapter. If a CIU 

has already submitted the specific information required in a permit application or data disclosure form 

and the information is still current, it need not be reproduced and resubmitted in the BMR. The BMR is a 

one-time report, unless changes in the federal categorical standards require submission of a new or 

updated BMR. 

At least 90 days before beginning discharge, new sources are required to submit the above 

information, excluding the certification from the qualified professional regarding consistent compliance 

(because compliance from initial date of discharge is expected) and compliance schedule (although new 

sources must provide information on the treatment method that the source intends to use to meet the 

applicable pretreatment standards). 

5-2 Introduction to the National Pretreatment Program 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

Compliance Schedule Progress Report [40 CFR 403.12(c)(3)] 

A CIU that is not in compliance with applicable categorical standards by the time the standards 

are effective might have to modify process operations or install treatment facilities to comply. Federal 

regulations require that the POTW develop and impose a compliance schedule for the CIU to install 

technology to meet applicable standards. As part of the BMR, a CIU that is unable to comply with the 

categorical standards must include a schedule for attaining compliance with the discharge standards. The 

final compliance or completion date in the schedule may not be later than the final compliance date 

specified in the categorical standards. Where authorized to do so, the POTW may require compliance 

earlier than the final compliance date specified in the federal regulations. 

Compliance schedules must include increments of progress in the form of dates (not to exceed 9 

months per event) for beginning and completing major actions leading to construction and operation of a 

pretreatment system or in-plant process modifications. Major activities could include hiring an engineer, 

completing preliminary analysis and evaluation, finalizing plans, executing a contract for major 

components, beginning construction, completing construction, or testing operation. 

In addition, the CIU must submit progress reports to the POTW no later than 14 days following 

each date in the compliance schedule (and final date for compliance) that include the following: 

 A statement of the CIU's status with respect to the compliance schedule 

 A statement of when the CIU expects to be back on schedule if it is falling behind and the 

reason for the delay and steps the CIU is taking to return to the established schedule. 

The POTW should review the reports as quickly as possible. When a CIU is falling behind 

schedule, the POTW should maintain close contact with the CIU. If the CIU fails to demonstrate good 

faith in meeting the schedule, the POTW can consider initiating appropriate enforcement action to correct 

the problem(s). 

Although EPA regulations require the compliance schedule progress report only for schedules 

submitted with a BMR, EPA recommends such incremental progress reporting for any compliance 

schedule. 

90-Day Compliance Report [40 CFR 403.12(d)] 

Section 403.12(d) of the General Pretreatment Regulations requires a CIU to submit the results of 

the self-monitoring of its wastewater discharge(s) to the POTW in a final compliance report. An existing 

source must file a final compliance report within 90 days following the final compliance date specified in 

a categorical regulation or within 90 days of the compliance date specified by the POTW, whichever is 

earlier. A new source must file a compliance report within 90 days of beginning discharge to the POTW. 

The report must contain the following: 

 Flow measurements (average daily and maximum daily) for regulated process 

wastestreams and nonregulated wastestreams, where necessary. 

 Categorical pretreatment standards applicable to each regulated process. In cases where the 

standard requires compliance with a BMP or pollution-prevention alternative, the CIU 

must submit documentation as required by the POTW or the applicable standards to 

determine compliance with the standard. 

 Sampling and analysis results (daily maximum, average concentration, and mass [where 

applicable]). 

Introduction to the National Pretreatment Program 5-3 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

 Time, date, and place of sampling; methods of analysis; certification that sampling and 

analysis is representative of normal work cycles and expected pollutant discharges to the 

POTW. 

 Certification, by a qualified professional, reviewed by a representative of the CIU, of 

whether applicable pretreatment standards are being met and, if not, a description of the 

additional operation and maintenance or pretreatment facilities that are needed to comply 

with the standards. In cases where the POTW performs the required sampling and analysis 

in lieu of the IU, the IU is not required to submit the compliance certification. 

Again, in addition to the certification statement noted above, 90-day compliance reports must be 

signed and certified by an authorized representative of the CIU as detailed in 40 CFR 403.12(l) and as 

described later in this chapter. 

For CIUs subject to equivalent mass or concentration limits established by the POTW [40 CFR 

403.6(c)], the report must contain a reasonable measure of the IU’s long-term production rate. For CIU 

subject to categorical pretreatment standards expressed in terms of allowable pollutant discharge per unit 

of production (or another measure of operation), the report must include the IU’s actual production during 

the appropriate sampling period. 

Periodic Compliance Report [40 CFR 403.12 (e)] 

After the final compliance date or, in the case of a new source, after beginning the discharge into 

the POTW, CIUs (except NSCIUs) are required to submit, in June and December, the self-monitoring

results of their wastewater discharge(s). The POTW may modify the months in which the reports are to be 

submitted. In addition, CIUs might need to report more frequently as required in the pretreatment 

standards, by the POTW, or by the Approval Authority. All results for self-monitoring performed must be 

reported to the POTW, even if the CIU is monitoring more frequently than required. Periodic compliance 

reports must include the following: 

 The nature and concentration of pollutants limited by applicable categorical standards or 

required by the POTW 

 Flow data (average and maximum daily) as required by the POTW 

 Mass of pollutants discharged (applicable to CIUs where mass limits have been imposed) 

 Production rates (applicable to CIUs where equivalent limits have been imposed or where 

limits imposed are expressed in allowable pollutant discharged per unit of production) 

 Documentation required by the POTW or the pretreatment standard necessary to determine 

the compliance status of the IU (applies to CIUs with pretreatment standards that require 

compliance with a BMP). 

For a CIU determined by the POTW to be an MTCIU [40 CFR 403.12(e)(3)], the POTW may 

reduce the minimum requirement to report from twice a year to once a year, unless more frequent 

reporting is required in the pretreatment standard or by the Approval Authority. A CIU must immediately 

resume self-monitoring and reporting at least twice a year if it is determined that it is no longer an 

MTCIU. 

A CIU that the POTW has classified as an NSCIU is not required to submit the periodic 

compliance report. Instead, the CIU must annually submit a certification statement with the alternative 

report required by the POTW [40 CFR 403.12(q)]. 

As a result of the Streamlining Rule, POTWs may update their programs to include the authority 

to allow an IU subject to a categorical pretreatment standard to forego sampling of a pollutant regulated 

5-4 Introduction to the National Pretreatment Program 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

by that categorical pretreatment standard if the CIU has demonstrated through sampling and other 

technical factors that the pollutant is neither present nor expected to be present in the discharge, or is 

present only at background levels from intake water and without any increase in the pollutant resulting 

from activities of the CIU. The POTW must receive approval from the Approval Authority before 

implementing the program update. To be authorized to forego this sampling, the IU must provide the 

sampling data and meet the requirements in 40 CFR 403.12(e)(2). Non-detectable sample results may be 

used only as a demonstration that a pollutant is not present if the EPA-approved method from 40 CFR 

Part 136 with the lowest minimum detection level for that pollutant was used in the analysis. This 

monitoring waiver does not supersede certification processes and requirements established in categorical 

pretreatment standards, except as otherwise specified in the categorical pretreatment standard. 

For a CIU authorized by the POTW to forego sampling of a pollutant regulated by a categorical 

pretreatment standard, the CIU must certify on each report, using the statement in 40 CFR 

403.12(e)(2)(v), that there has been no increase in the pollutant in its wastestream from activities of the 

IU. The monitoring waiver is valid only for the duration of the effective period of the IU’s control 

mechanism, but it may not be longer than 5 years. The CIU must submit a new request for the waiver 

before the waiver can be granted for each subsequent control mechanism. 

Upset Report [40 CFR 403.16] 

An upset is defined as an exceptional incident in which there is unintentional and temporary 

noncompliance with categorical standards due to factors beyond the reasonable control of the CIU. An 

upset does not include noncompliance to the extent caused by operational error, improperly designed or 

inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. CIUs 

are allowed an affirmative defense for noncompliance with categorical standards if they can demonstrate 

that the noncompliance was the result of an upset. The regulations in 40 CFR 403.16 detail the conditions 

necessary to demonstrate that an upset has occurred, and they require the CIU to submit at least an oral 

report to the POTW within 24 hours of becoming aware of the upset. The report must contain the 

following information: 

 A description of the indirect discharge and the cause of the noncompliance 

 The date(s) and times of the noncompliance 

 Steps being taken or planned to reduce, eliminate, and prevent reoccurrence of the 

noncompliance. 

If the CIU provides the notification orally, it must also submit a written report within 5 days. In 

any enforcement action, the CIU has the burden of proof in establishing that an upset has occurred. EPA 

is responsible for determining the technical validity of the claim. 

Significant Industrial User Reporting Requirements 

Periodic Compliance Report [40 CFR 403.12 (h)] 

After the final compliance date, SIUs not subject to categorical pretreatment standards must 

submit to the POTW at least once every 6 months (on dates specified by the POTW) a description of the 

nature, concentration, and flow of the pollutants required to be reported by the POTW. EPA established a 

minimum frequency of once every 6 months, determining that to be adequate for IUs that have little 

potential to cause pass through or interference, to contaminate the sewage sludge, or to otherwise violate 

pretreatment standards or requirements. EPA assumes that larger IUs and those that have more potential 

to cause problems or violate standards would be required by the POTW to sample and report more often. 

All results for self-monitoring performed must be reported to the POTW, even if the IU is monitoring 

Introduction to the National Pretreatment Program 5-5 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

more frequently than required (40 CFR 403.12(g)(6)). Periodic compliance reports must include the 

following:

 The nature and concentration of pollutants as required by the POTW 

 Flow data (average and maximum daily) as required by the POTW 

 Documentation required by the POTW necessary to determine the compliance status of the 

IU (applies to SIUs with local limits or other requirements that require compliance with a 

BMP). 

Slug Control Plan [40 CFR 403.8(f)(2)(vi)] 

POTWs must evaluate whether each SIU needs a plan or other action to control slug discharges. 

A slug discharge is any discharge of a nonroutine, episodic nature, including an accidental spill or 

noncustomary batch discharge that has a reasonable potential to cause interference or pass through, or in 

any other way violate the POTW’s regulations, local limits, or permit conditions. For IUs identified as 

SIUs before November 14, 2005, this evaluation must have been conducted at least once by October 14, 

2006; additional SIUs must be evaluated within one year of being so designated. To accurately evaluate 

the slug potential, POTWs likely will have to examine the SIU during its normal operating conditions. If 

undetected, slug discharges can have serious effects on the POTW. EPA’s 1991 Control of Slug Loadings 

to POTWs Guidance Manual provides procedures for developing, implementing, and reviewing slug 

control plans. If the POTW determines that a slug control plan is needed, the SIU must submit a plan that 

contains at least the following elements [40 CFR 403.8(f)(2)(vi)]: 

 Description of discharge practices, including nonroutine batch discharges 

 Description of stored chemicals 

 Procedures for immediately notifying the POTW of slug discharges with procedures for 

follow-up, written notification within 5 days 

 If necessary, procedures to prevent adverse effects from accidental spills, including 

inspecting and maintaining storage areas, handling and transferring materials, loading and 

unloading operations, controlling plant site runoff, worker training, building containment 

structures or equipment, measures for containing toxic organic pollutants (including 

solvents), or measures and equipment for emergency response. 

Bypass Report [40 CFR 403.17] 

The General Pretreatment Regulations define bypass as the intentional diversion of wastestreams 

from any portion of an IU’s treatment facility. If a bypass results in noncompliance, even if it resulted 

from performing essential maintenance, the IU must provide a report to the POTW detailing a description 

of the bypass and the cause, the duration of the bypass, and the steps being taken or planned to reduce, 

eliminate, and prevent reoccurrence of the bypass. 

The IU must provide oral notice to the POTW within 24 hours of detecting an unanticipated 

bypass; a written follow-up is due within 5 days. For an anticipated bypass, the IU must submit notice to 

the POTW, if possible at least 10 days before the intent to bypass. 

5-6 Introduction to the National Pretreatment Program 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

Signatory and Certification Requirements [40 CFR 403.12(l)] 

Pursuant to 40 CFR 403.12(l), BMRs, 90-day compliance reports and periodic compliance reports 

from CIUs must be signed by an authorized representative of the facility and must contain a certification 

statement attesting to the integrity of the information reported. The reports must be signed by one of the 

following: 

 A responsible corporate officer if the IU is a corporation; a responsible corporate officer is 

defined as either of the following: 

– A president, secretary, treasurer, or vice-president of the corporation in charge of a 

principal business function 

– The manager of one or more manufacturing, production, or operating facilities, provided 

the manager is authorized to make management decisions that govern the operation of the 

regulated facility, including having the explicit or implicit duty of making major capital 

investment recommendations, and initiate and direct other comprehensive measures to 

assure long-term environmental compliance with environmental laws and regulations; 

can ensure that the necessary systems are established or actions taken to gather complete 

and accurate information for control mechanism requirements; and where authority to 

sign documents has been assigned or delegated to the manager in accordance with 

corporate procedures 

 A general partner or proprietor if the IU is a partnership or sole proprietorship 

 A duly authorized representative of the above-specified persons if such authorization is in 

writing, is submitted to the POTW, and specifies a person or position having overall 

responsibility for the facility where the discharge originates or having overall 

responsibility for environmental matters for the facility. 

As required in 40 CFR 403.6(a)(2)(ii), the certification statement must read as follows: 

I certify under penalty of law that this document and all attachments were prepared under 

my direction or supervision in accordance with a system designed to assure that qualified 

personnel properly gather and evaluate the information submitted. Based on my inquiry 

of the person or persons who manage the system, or those persons directly responsible for 

gathering the information, the information submitted is, to the best of my knowledge and 

belief, true, accurate, and complete. I am aware that there are significant penalties for 

submitting false information, including the possibility of fine and imprisonment for 

knowing violations. 

Although federal regulations require POTWs to require these signatures and certifications from 

CIUs only, many POTWs have found it important to impose the requirements for all IU reports. To 

facilitate compliance, many POTWs have developed forms that include the certification statement and 

signatory requirements for use by all IUs. 

Cross-Media Electronic Reporting [40 CFR Part 3] 

The Cross-Media Electronic Reporting Rule (CROMERR) promulgated in October 2005 provides 

the legal framework for electronic reporting under all of EPA's environmental regulations. The POTW 

that chooses to receive electronic documents must satisfy the requirements of 40 CFR Part 3, specifically, 

the following electronic reporting provisions: 

 Modify current requirements in the CFR to remove any obstacles to electronic reporting 

Introduction to the National Pretreatment Program 5-7 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

 Allow regulated entities to submit any report electronically, but only after EPA announces 

that electronic reporting is available for the specific report 

 Require submission of electronic reports to EPA's Central Data Exchange (CDX) or to 

another designated EPA system 

 Require validation of electronic signatures on reports submitted to EPA through CDX (or 

another designated EPA system) and ensure that valid electronic signatures have the same 

legal force as their wet-ink counterparts 

 Set forth requirements that EPA-authorized programs must satisfy when implementing 

electronic reporting, and provide a streamlined process for these programs to obtain EPA 

approval of their electronic reporting implementation. 

SELF-MONITORING REQUIREMENTS

All SIUs, including CIUs, must conduct self-monitoring as part of several different reporting 

requirements as noted earlier. For CIUs, that includes the BMR, 90-day compliance report, and periodic 

compliance reports [40 CFR 403.12(b), (d), and (e), respectively]. Noncategorical SIUs are required to 

self-monitor as part of the periodic reporting requirements [40 CFR 403.12(h)]. Those reports must be 

based on data that were obtained through appropriate sampling and analysis performed during the period 

covered by the report and are representative of conditions occurring during the reporting period. The 

monitoring must occur at a frequency necessary to assess and assure compliance by IUs with applicable 

pretreatment standards and requirements. In cases where a violation is identified, the IU must repeat the 

sampling and analysis for the pollutant in violation and submit the results within 30 days after becoming 

aware of the violation. Resampling is not required if the conditions in 40 CFR 403.12(g)(2)(i) and (ii) are 

met. 

The POTW may choose to monitor in lieu of the IU’s performing the self-monitoring. In cases 

where a violation is identified and the POTW has assumed responsibility for sampling in lieu of the SIU, 

the POTW must repeat sampling and analysis within 30 days of becoming aware of an exceedance. The 

only exception to that requirement is if the POTW specifically requires the IU to perform the repeat 

analysis. 

As noted in 40 CFR 403.12(g)(5), sample collection and analysis for all required pretreatment 

program reports must be conducted using 40 CFR Part 136 procedures (as amended) or with any other 

test procedures approved by the EPA Administrator. To demonstrate compliance with those requirements, 

IUs may have to submit information regarding sample handling and analytical procedures to the POTW. 

Developing standardized forms for use by IUs and their testing labs can facilitate documentation and 

submission of all required information and can streamline the IU and POTW review process. For 

additional information on sample collection and analysis procedures, refer to chapter 4 of this manual and 

EPA’s Industrial User Inspection and Sampling Manual for POTWs. 

On the basis of the specific pollutants regulated by categorical pretreatment standards, different 

types of samples might have to be collected. Grab samples must be used for pH, cyanide, total phenols, 

oil and grease, sulfide, and volatile organic compounds. For all other pollutants, 24-hour, flowproportional composite samples must be collected. The POTW may waive flow-proportional composite 

sampling if an IU demonstrates that a different type of sampling will provide a representative sample. In 

such cases, time-proportional composite or grab samples, if representative, may be collected. Multiple 

grab samples collected during 24-hour period may be composited before the analysis as follows: for 

cyanide, total phenols, and sulfides, the samples may be composited in the laboratory or in the field; for 

volatile organics and oil and grease the samples may be composited in the laboratory. Composite samples 

for other parameters unaffected by the compositing procedures as documented in approved EPA 

5-8 Introduction to the National Pretreatment Program 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

methodologies may be authorized by the POTW, as appropriate. The decision to allow time-proportional 

composite or grab sampling must be documented in the IU file for the facility. 

For BMR and 90-day compliance reports, a minimum of four grab samples must be collected for 

pH, cyanide, total phenols, oil and grease, sulfide, and volatile organics. If those pollutants are not 

regulated by the specific categorical standard, monitoring is not required. The POTW may authorize a 

lower number of samples to be collected for facilities with historical sampling data. Samples should be 

taken immediately downstream from pretreatment facilities if they exist or immediately downstream from 

the regulated process if no pretreatment exists. If other wastewaters are mixed with the regulated 

wastewater before pretreatment, the IU should measure the flows and concentrations necessary to allow 

use of the CWF to evaluate compliance with the pretreatment standards. Where an alternate concentration 

or mass limit has been calculated by the IU using the CWF, the adjusted limit along with supporting data 

must be submitted to the POTW. 

For periodic compliance reports [40 CFR 403.12(e) and (h)], the POTW must require the number 

of grab samples necessary to assess and assure compliance by IUs with applicable pretreatment standards 

and requirements. The POTW must ensure that each IU’s control mechanism specifies sampling 

location(s), required sampling frequencies, sample types to be collected, sampling and analytical 

procedures (40 CFR Part 136), and associated reporting requirements. 

In certain instances, CIUs subject to TTO (total toxic organics) standards may implement 

alternatives in lieu of monitoring all regulated toxic organic compounds. A list of categories that contain 

TTO standards is provided in chapter 3. For example, the electroplating and metal finishing standards 

allow IUs to monitor for only those toxic organic compounds that are reasonably expected to be present. 

Additional TTO guidance related to the electroplating and metal finishing categories is provided in EPA’s 

1984 Guidance Manual for Electroplating and Metal Finishing Pretreatment Standards.

For certain industries (e.g., electroplating, metal finishing, and electrical and electronic 

components), POTWs have the option of allowing the CIU to prepare and implement a toxic organic 

management program (TOMP) in lieu of periodic monitoring. In those instances, the TOMP should 

identify all potential sources from which toxic organic materials could enter the wastestream and propose 

control measures to eliminate the possibility. Where a TOMP is allowed, an IU can demonstrate 

compliance by adhering to the TOMP and submitting periodic certification statements attesting to the 

facts that no dumping of concentrated toxic organic pollutants has occurred and that the facility’s TOMP 

is being implemented. 

TOMPs cannot be used in lieu of monitoring for BMRs and 90-day compliance reporting 

requirements. In addition, the POTW may not waive the semiannual certification requirement or TTO 

monitoring requirement through a mechanism such as a pollutants not present waiver. 

The categorical standards for some industries (i.e., aluminum forming, copper forming, coil 

coating, and metal molding and casting) allow IUs to monitor oil and grease as an alternative to TTO 

monitoring. This option may be used to fulfill the TTO monitoring requirements of the BMR, 90-day 

compliance report, and periodic compliance reports, and it allows the IU to determine whether it wants to 

demonstrate compliance with the TTO or the oil and grease standards. A detailed description of TTO 

monitoring requirements is provided in EPA’s 1985 Guidance Manual for Implementing Total Toxic 

Organics (TTO) Pretreatment Standards. 

Introduction to the National Pretreatment Program 5-9 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

Categorical standards for certain industrial categories allow IUs to submit a certification to 

exempt them from monitoring for one or more pollutants. For example, 

 IUs from two categories (aluminum forming and coil coating) may choose to submit an 

annual certification requesting exemption for cyanide from the second semiannual selfmonitoring event. 

 IUs belonging to the pharmaceutical manufacturing category may choose to submit a 

certification requesting exemption from monitoring for cyanide and other regulated 

pollutants that are neither used nor generated at the facility.. 

 IUs belonging to the category of porcelain enameling may choose to submit an annual 

certification requesting exemption from the second semiannual self-monitoring event for 

chromium. 

 Certain facilities in the pulp and paper categories may choose an alternative monitoring 

program by certification once every 5 years if they use a totally chlorine free process. 

Certain facilities in this category can also submit certifications in lieu of monitoring for 

pentachlorophenol and trichlorophenol if they do not use those compounds in their 

biocides. 

 IUs belonging to the steam electric category may choose to provide a demonstration and 

certification that regulated parameters are not detectable in the final discharge (except 

chromium and zinc). 

 Certain facilities in the electroplating, metal finishing, and electrical and electronic 

components categories may choose to submit a TTO certification semiannually in lieu of 

TTO monitoring, but such facilities must also develop and submit a TOMP. 

 Centralized waste treatment facilities that opt for regulation under Subpart D must certify 

annually that they are operating their treatment systems to provide equivalent treatment as 

set forth in their initial certification. 

Although the Streamlining Rule allows for reduced monitoring under the pollutants not present 

provision [40 CFR 403.12(e)(2)], the Streamlining Rule does not supersede the applicable certification 

processes and requirements established in the categorical pretreatment standards. 

NOTIFICATION REQUIREMENTS

Notification of Production Level Change in the Equivalent Limit Calculation [40 

CFR 403.6(c)(9)] 

Any IU operating under a control mechanism that incorporates equivalent mass or equivalent 

concentration limits calculated from a production-based standard must notify the POTW within 2 

business days after the IU has a reasonable basis to know that the production level will significantly 

change within the next calendar month. 

Notification of Material/Significant Change in the Alternative Limit Calculation [40 

CFR 403.6(e)] 

Where process effluent is mixed before treatment with wastewaters other than those generated by 

the regulated process, fixed alternative discharge limits may be derived by the POTW or by the IU with 

the written concurrence of the POTW. An IU must immediately report to the POTW any material or 

significant change in the values used in the calculation. 

5-10 Introduction to the National Pretreatment Program 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

Notification of Waived Pollutant Present [40 CFR 403.12(e)(2)(vi)] 

The POTW may authorize the IU subject to a categorical pretreatment standard to forego 

sampling of a pollutant regulated by the categorical pretreatment standard if the IU has demonstrated 

through sampling and other technical factors that the pollutant is neither present nor expected to be 

present in the discharge, or is present only at background levels from intake water and without increase in 

the pollutant because of activities of the IU. This authorization is subject to the conditions listed in 40 

CFR 403.12(e)(2). If a waived pollutant is found to be present or is expected to be present because of 

changes that occur in the IU’s operation, the IU must immediately do the following: 

 Begin self-monitoring twice per year or more frequently if required by the POTW. 

 Notify the POTW. 

Notification of Middle-Tier Categorical Industrial User 40 CFR 403.12(e)(3)(iv)] 

A CIU that the POTW has determined to be an MTCIU must notify the POTW if the CIU no 

longer meets the conditions that qualify it as a middle-tier user. The CIU must also immediately begin 

complying with the semiannual self-monitoring and reporting requirements. 

Notification of Potential Problems Including Slug Loading [40 CFR 403.12(f)] 

All IUs are required to notify the POTW immediately of any discharges that could cause 

problems. The discharges include spills, slug loads, or any other discharge that could cause a problem at 

the POTW. 

Noncompliance Notification and Repeat Sampling Report [40 CFR 403.12(g)(2)] 

If monitoring performed by an IU indicates noncompliance, the IU is required to notify the 

POTW within 24 hours of becoming aware of the violation. In addition, the IU must repeat the sampling 

and analysis for the pollutant in violation and report the results of the resampling within 30 days of 

becoming aware of the original violation. The repeat sampling is not required if the POTW samples the 

IU at least once per month or if the POTW samples the IU between the time of the original sample and 

the time the results of the sampling were received. 

Notification of Changed Discharge [40 CFR 403.12(j) and 40 CFR 122.42(b)] 

All IUs are required to promptly notify the Control Authority (and the POTW if the POTW is not 

the Control Authority) in advance of any substantial changes in the volume or character of pollutants in 

their discharge. As a general rule, changes greater than 20 percent are considered substantial. An IU is 

also required to notify the POTW immediately of any changes at its facility that affect the potential for a 

slug discharge [40 CFR 403.8(f)(2)(vi)]. An IU must also provide notification if it expects to discharge a 

pollutant for which it has been granted a waiver under the pollutants not present provision [40 CFR 

403.12(e)].

Notification of Discharge of Hazardous Wastes [40 CFR 403.12(p)] 

IUs discharging more than 15 kilograms per month of a waste that, if otherwise disposed of, 

would be a hazardous waste pursuant to the Resource Conservation and Recovery Act (RCRA) 

requirements under 40 CFR Part 261 are required to provide a one-time written notification of such 

discharge to the POTW, state, and EPA. IUs discharging any amount of waste that, if disposed of 

otherwise, would be an acutely hazardous waste pursuant to RCRA must also provide the notification. 

The written notification must contain the EPA hazardous waste number and the type of discharge (i.e., 

Introduction to the National Pretreatment Program 5-11 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

batch, continuous). If the IU discharges more than 100 kilograms per month of the hazardous waste, the 

written notification must also include, at a minimum the following: 

 An identification of the hazardous constituent in the IU's discharge 

 An estimate of the mass and concentration of the constituents in the IU's discharge 

 An estimate of the mass and concentration of constituents in the IU's discharge in a year. 

IUs must also provide a certification accompanying this notification that a waste-reduction 

program is in place to reduce the volume and toxicity of hazardous wastes to the greatest degree 

economically practical. Within 90 days of the effective date of the listing of any additional hazardous 

wastes pursuant to RCRA, IUs must provide a notification of the discharge of such wastes. 

Notification of Upset [40 CFR 403.16] 

A CIU must notify the POTW with the information required in 40 CFR 403.16(c)(3) within 24 

hours of becoming aware of the upset. If CIU provides the information orally, it must also provide a 

written submission within 5 days. 

Notification of Bypass [40 CFR 403.17] 

If an IU knows in advance of the need for a bypass, it must submit prior notice to the POTW, if 

possible at least 10 days before the date of the bypass. An IU must submit oral notice of an unanticipated 

bypass that exceeds applicable pretreatment standards to the POTW within 24 hours from the time the IU 

becomes aware of the bypass. 

RECORD-KEEPING REQUIREMENTS

IUs are required to maintain records of their monitoring activities (including documentation 

associated with BMPs) [40 CFR 403.12(O)]. At a minimum, information documented must include the 

following: 

 Sampling methods, dates and times 

 Identity of the person(s) collecting the samples and of the sampling location(s) 

 The dates the analyses were performed and the methods used 

 The identity of the person(s) performing the analyses and the results of the analyses 

 Other information necessary to document compliance with applicable BMPs 

The IU must retain those records for at least 3 years, or longer in cases where there is pending 

litigation involving the POTW or IU, or when requested by the Approval Authority. These records must 

be available to the POTW and Approval Authority for review and copying. Historically, most POTWs do 

not dispose of any records; rather, they archive older records at an off-site location. 

5-12 Introduction to the National Pretreatment Program 
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

ATTACHMENT 5-1: SUMMARY OF REPORTING AND NOTIFICATION 

REQUIREMENTS FOR ALL IUS

Required 

report/notification and 

citation

Apply 

to

Report due date or notification 

requirement

Purpose of report or 

notification

Baseline Monitoring 

Report (BMR) 

40 CFR 403.12(b)(1–7)

CIUs Existing source—Within 180 days 

of effective date of the regulation 

or an administrative decision on 

category determination. 

New source—At least 90 days 

before beginning discharge.

- To provide basic information 

on the industrial facility to 

the POTW 

- To determine wastewater 

discharge sampling points 

- To determine compliance 

status with categorical 

pretreatment standards

Compliance Schedule 

Progress Reports 

40 CFR 403.12(c)(1–3)

CIUs Within 14 days of each milestone 

date on the compliance schedule; 

at least every 9 months.

- To track progress of the 

industrial facility through the 

duration of a compliance 

schedule submitted with a 

BMR

90-Day Compliance 

Report 

40 CFR 403.12(d)

CIUs Existing source—Within 90 days 

of the date for final compliance 

with applicable categorical 

pretreatment standard. 

New source—Within 90 days 

after beginning wastewater 

discharge to the POTW.

- To notify the POTW as to 

whether compliance with the 

applicable categorical 

pretreatment standards has 

been achieved 

- If facility is noncompliant, to 

specify how compliance will 

be achieved

Periodic Compliance 

Report 

40 CFR 403.12(e)

CIUs Existing source—Every June and 

December after the final 

compliance date, unless 

frequency is increased by the 

POTW. 

New source—Every June and 

December after beginning a 

discharge, unless frequency is 

increased by the POTW. 

Facilities designated as MTCIUs 

by the POTW may be authorized 

to report annually. Facilities 

designated as NSCIUs by the 

POTW do not need to submit 

periodic compliance reports. 

NSCIUs must submit a 

certification statement with the 

alternative report required by the 

POTW [40 CFR 403.12(q)].

- To provide the POTW with 

current information on the 

discharge of pollutants to the 

POTW from categorical 

industries and the 

compliance status of the 

user

Notification of 

Potential Problems 

including Slug 

Loadings 

40 CFR 403.12(f) 

All IUs Notification to POTW 

immediately after occurrence of 

slug load, or any other discharge 

that could cause problems at the 

POTW.

- To alert the POTW to the 

potential hazards of the 

discharge

Introduction to the National Pretreatment Program 5-13 
Chapter 5: Industrial User Pretreatment Program Responsibilities 

5-14 Introduction to the National Pretreatment Program 

Required 

report/notification and 

citation

Apply 

to

Report due date or notification 

requirement

Purpose of report or 

notification

Noncompliance 

Notification and 

Repeat Sampling 

Report

40 CFR 403.12(g)(2) 

All IUs Notification to POTW within 24 

hours of becoming aware of 

violation. Repeat sampling and 

analysis and submit the results to 

the POTW 30 days after 

becoming aware of the violation. 

- To alert the POTW of a 

known violation and 

problems that could occur

Periodic Compliance 

Reports for 

Noncategorical Users 

40 CFR 403.12(h) 

NonCat. 

SIUs

Every 6 months on dates 

specified by the POTW unless 

the frequency is increased by the 

POTW.

- To provide the POTW with 

current information on the 

discharge of pollutants to the 

POTW from IUs not 

regulated by categorical 

standards

Notification of 

Changed Discharge 

40 CFR 403.12(j) 

All IUs Before any substantial changes 

in the volume or character of 

pollutants in the discharge. In 

addition, 40 CFR 403.8(f)(2)(vi) 

requires IUs to notify POTWs of 

any changes at its facility 

affecting potential for a slug 

discharge.

- To notify the Control 

Authority (and the POTW if 

the POTW is not the Control 

Authority) of anticipated 

changes in wastewater 

characteristics and flow that 

could affect the POTW

Notification of 

Hazardous Wastes 

Discharge 

40 CFR 403.12(p) 

All IUs Existing source—Within 180 days 

of effective date of rule. 

New source—Within 180 days 

after commencement of 

discharge.

- To notify the POTW, EPA, 

and state of discharges of 

hazardous wastes under 40 

CFR Part 261

Notification of Upset 

40 CFR 403.16 

CIUs Within 24 hours of becoming 

aware of the upset. 

(Five days where 24-hour 

notification was provided orally,)

- To notify the POTW of 

unintentional and temporary 

noncompliance with 

categorical standards

Notification of Bypass 

40 CFR 403.17

All IUs Ten days before the date of the 

bypass or oral notice within 24 

hours of the IU’s becoming aware 

of the bypass, with written 

notification within 5 days.

- To notify the POTW of 

noncompliance and 

problems that could occur
Chapter 5. Industrial 4/29/2011User Pretreatment Program Responsibilities 

Introduction to the National Pretreatment Program 5-15 

ATTACHMENT 5-2: SUMMARY OF NOTIFICATION AND CITATION 

REQUIREMENTS THAT MIGHT NOT APPLY TO ALL IUS

Required 

report/notification and 

citation

Apply 

to

Report due date or 

notification requirement

Purpose of report or 

notification

Notification of 

Production Level 

Change in the 

Equivalent Limit 

Calculation 

40 CFR 403.6(c)(9)

CIUs Within 2 business days after 

the IU has a reasonable basis 

to know that the production 

level will significantly change 

within the next calendar 

month. 

- To notify the POTW of change 

in the production level used to 

calculate the equivalent mass 

or equivalent concentration 

limits in its control mechanism 

Notification of 

Material/Significant 

Change in the 

Alternative Limit 

Calculation 

40 CFR 403.6(e) 

CIUs Immediately report any 

material or significant change 

in the values used in the 

calculation. 

- To notify the POTW of change 

in the values used in 

calculating alternative limit for 

process effluent mixed before 

treatment with wastewaters 

other than those generated by 

the regulated process 

Notification of Waived 

Pollutant Present 

40 CFR 403.12(e)(2)(vi) 

CIUs Notify POTW of expected 

discharge of a pollutant for 

which it has been granted a 

waiver under the pollutant not 

present provision [40 CFR 

403.12(e)] and immediately 

comply with the monitoring 

requirements in 40 CFR 

403.12(e)(1) or more frequent 

monitoring requirements 

imposed by the POTW. 

- To alert the POTW that a 

waived pollutant is found to be 

present or is expected to be 

present because of changes 

that occur in the IU’s 

operations 

Notification of MiddleTiered Categorical 

Industrial User 

40 CFR 403.12(e)(3)(iv) 

CIUs Immediately notify the POTW 

of changes causing the IU to 

no longer meet the conditions 

for reduced reporting 

requirements that it has been 

granted. Upon notification, 

comply with the minimum 

reporting requirements in 40 

CFR 403.12(e)(1). 

- To alert the POTW that the IU 

no longer meets the conditions 

in 40 CFR 403.12(e)(3)(i) or (ii) 
Chapter 6. Hauled Wastes 

4. 

CHAPTER 6. 

HAULED WASTES

CERCLA Site Discharges to POTWs Guidance Manual (EPA 540G90005) 

Guidance Manual for the Identification of Hazardous Wastes Delivered to Publicly Owned Treatment Works by Truck, 

Rail, or Dedicated Pipe (EPA July 1987) 

Industrial User Inspection and Sampling Manual for POTWs (EPA 831-B-94-001) 

Industrial User Permitting Guidance Manual (EPA September 1989) 

RCRA Information on Hazardous Wastes to Publicly Owned Treatment Works (EPA September 1985) 

Guidance Manual for the Control of Waste Hauled to Publicly Owned Treatment Works 

(EPA-833B-98-003) 

Chapter 6. Applicable EPA Guidance 

In addition to receiving wastes through the collection system, many POTWs accept trucked 

wastes and, in a few instances, wastes received by train. As stipulated in 40 CFR 403.1(b)(1), pollutants 

from nondomestic sources that are transported to the POTW by truck or rail are also subject to the 

General Pretreatment Regulations. They may also be subject to categorical pretreatment standards. 

Therefore, hauled wastes from CIUs or hauled waste that otherwise qualifies the discharger as an IU must 

be regulated in accordance with the requirements of the General Pretreatment Regulations, including any 

applicable requirements for permitting and inspecting the generating facility. Hauled wastes, like wastes 

received through the collection system, have the potential to negatively affect the POTW, making 

regulatory control of the wastes necessary. 

POTWs have seen an increase in the frequency of uncontrolled discharges to POTWs from waste 

haulers. Because of their unique nature, waste haulers are not regulated in the same way as other types of 

IUs. Because only minimal federal regulatory controls exist, some POTWs have developed hauled waste 

control programs. In addition, hauled waste could be subject to RCRA requirements at 40 CFR 270.60(c). 

For more information on hauled waste, refer to EPA’s 1999 Guidance Manual for the Control of Waste 

Hauled to Publicly Owned Treatment Works.

NATURE OF HAULED WASTES

Wastes are hauled to POTWs for several 

reasons. By far, most hauled waste is domestic 

septage (figure 6-1), typically from homes outside 

the POTW’s service area but compatible in nature. 

Because such discharges are predominantly 

compatible wastes, treatment at a POTW is the 

most appropriate disposal method. Wastes are 

regularly hauled to POTWs for a variety of 

reasons, including the following: 

Domestic septage is defined as the liquid or solid material 

removed from a septic tank, cesspool, portable toilet, Type III 

marine sanitation device, or similar system that holds only 

domestic sewage. Domestic septage does not include liquid 

or solid material removed from any system that receives 

either commercial wastewater or industrial wastewater, and it 

does not include grease removed from a restaurant grease 

trap [40 CFR part 503.9(f)]. 

Figure 6-1. Definition of domestic septage. 

 The facility is outside the POTW’s service area (e.g., is in a rural area) and is not 

connected to the collection system. 

Introduction to the National Pretreatment Program 6-1 
Chapter 6. Hauled Wastes 

 The wastes might be known to cause collection system problems but can be treated at the 

wastewater treatment plant (e.g., grease trap cleanout wastes). Some wastes might even be 

beneficial to the POTW (fats, oil, and grease, for example) for energy generation. 

 The facility is connected to the sewer but does not have the capacity to discharge the 

volume of waste generated (e.g., groundwater remediation activities at an IU). 

 A POTW rejects acceptance of a waste from an IU, forcing the IU to haul the waste to a 

different POTW that agrees to accept the waste. 

Common to all of these wastes is the fact that the POTW cannot know for certain the nature and 

concentration of the wastes as hauled without implementing some type of control or surveillance 

program. 

CONTROL PROGRAMS

Section 403.5(b)(8) of the General Pretreatment Regulations specifically prohibits the 

introduction of any trucked or hauled pollutants to the POTW, except at discharge points designated by 

the POTW. That is the only pretreatment requirement specifically addressing hauled wastes, although if 

the type of hauled waste qualifies the discharger as a CIU or IU, program requirements for those types of 

users would apply. However, even where only minimal regulatory requirements exist for the hauled 

waste, many POTWs have determined that additional controls are necessary to further regulate such 

discharges and to prevent adverse effects from them. These control programs include practices such as 

permitting, sampling, manifesting, surveillance, and other forms of hauler documentation. In many 

instances, these control programs have unintentionally shifted the hauling of waste from one POTW to 

other POTWs that are not implementing such a program. Most often, it is the smaller POTWs that do not 

have hauler control programs, including many POTWs that are not even required to implement a 

pretreatment program. The effect of this change from larger to smaller POTWs and from more to less 

control is that there has been an increase in negative effects on POTWs and receiving streams. Two 

options for addressing that concern are (1) for the smaller and non-pretreatment POTWs to initiate waste 

hauler control programs or (2) for the larger POTWs to institute sound control programs that adequately 

regulate these wastes without driving haulers to search for other, less-restrictive disposal alternatives. Any 

POTW waste hauler control program should address the following six elements: 

 Effect on POTW. Before accepting new waste from a hauler, the POTW should evaluate 

the potential effects on the treatment works from the waste. POTWs may require haulers or 

generators of hauled waste to perform a treatability study to demonstrate the effectiveness 

of treatment on the waste. POTWs must evaluate the potential effects of the waste when 

developing local limits and when considering the adequacy of existing local limits or the 

need to revise them. The POTW must include the hauled waste loadings as part of the 

loading allowances in its local limits development process, even if the POTW decides that 

the waste can be safely accepted for treatment purposes and separate permitting is not 

applied. 

 Permitting. A permit is the most direct and efficient method of regulating waste haulers. 

Permits provide the opportunity to monitor and regulate haulers because of the nature of 

the hauled waste and the potential effects of that waste on the POTW. Unique permit 

conditions include right of refusal, daily flow limitations, discharge time limits, and 

reporting and certification requirements. 

 Discharge point. As specified in the General Pretreatment Regulations, hauled waste can 

be discharged only at points designated by the POTW. This requirement provides the 

POTW with the ability to control and observe these discharges at specified locations, 

thereby minimizing the potential for adverse effects. 

6-2 Introduction to the National Pretreatment Program 
Chapter 6. Hauled Wastes 

 Monitoring. The POTW should institute a monitoring program to evaluate the nature and 

concentration of discharges. Both POTW monitoring and hauler self-monitoring may be 

appropriate. Many POTWs require sampling of all loads of hauled waste (pH, temperature, 

conductivity); however, they perform analyses on only a predetermined percentage of the 

wastes or when problems occur as a result of the hauled waste discharge. Unanalyzed 

samples are refrigerated and kept for several weeks or months until the POTW is certain 

that the waste has not affected the POTW. The frequency of sampling may also depend on 

the variability of the waste. Each load from a hauler that delivers highly variable loads 

might have to be sampled and analyzed, whereas a much smaller percentage might be 

appropriate for more consistent waste types. As noted earlier, all federal, state, and local 

discharge limitations apply to such wastes. Even where the discharger is not a CIU or SIU, 

the POTW could also consider inspecting the waste generators to confirm the source of the 

wastes. 

 Hauler documentation. The POTW should require waste haulers to document the source 

of wastes being discharged, potentially requiring manifests. Manifests should include 

general hauler information, information on the waste generator (e.g., name, address, and 

phone number), the type of wastes collected, volumes, known or suspected pollutants, and 

certification that the load is not a hazardous waste. A useful technique is to contact the 

waste generators to verify the information on the manifest. 

 Legal authority. If not already in place, the POTW’s local ordinance (and approved 

pretreatment program) should be modified to add language specifying all the controls that 

are applicable to waste haulers. Doing so ensures that waste haulers and POTW personnel 

know the procedures, expectations, liabilities, and such, associated with the control 

program. 

In addition to the specific controls described above, POTWs should implement procedures to 

identify and eliminate illegal discharges. Procedures can include periodic sewer line sampling, 

surveillance of suspected unpermitted discharge points, education of industries regarding hauled waste, 

increased enforcement, and public awareness of illegal dumping. 

CONCERNS

Every discharge has the potential to affect the POTW. Unlike discharges from IUs directly 

connected to the POTW, the makeup of a load of hauled waste is virtually unknown without some type of 

monitoring, be it visual or analytical. Most waste haulers are reputable business people who provide a 

valuable service to the public and industry; however, the unique attributes of hauled waste can be 

devastating when unethical haulers dump incompatible wastes at POTWs. Even loads of domestic septage 

can cause problems for a POTW due to high strength or discharge rate. Domestic septage can be partially 

digested, can be higher in metals concentrations than normal domestic wastes, or can contain small 

amounts of household contaminants (e.g., cleaners). Similarly, disinfectants used in portable toilets have 

the potential to affect POTW operations. 

Receipt of hauled hazardous waste (as defined in RCRA) not only might affect POTW operations 

but also could subject the POTW to additional reporting requirements. The Domestic Sewage Exclusion, 

specified in 40 CFR 261.4(a)(1)(ii), provides that hazardous wastes mixed with domestic sewage are 

exempt from the RCRA waste regulations. However, hazardous wastes received by truck or rail (or 

dedicated pipe) at the treatment plant are not exempt from the regulations. POTWs that accept hazardous 

wastes from those sources are subject to permit by rule status under RCRA [40 CFR 270.60(c)] provided 

that certain requirements are met. The two most significant conditions are that the POTW must be in 

compliance with all its NPDES permit requirements and that the waste must comply with all federal, 

Introduction to the National Pretreatment Program 6-3 
Chapter 6. Hauled Wastes 

6-4 Introduction to the National Pretreatment Program 

state, and local pretreatment requirements. Under 40 CFR 403.12(p), IUs are required to notify the POTW 

and other waste management authorities of hazardous waste discharges into the POTW. Nationwide, very 

few POTWs are knowingly accepting hauled hazardous waste. 

POTWs should be aware that hauled process wastes from facilities subject to federal categorical 

pretreatment standards are still subject to those standards. That condition highlights the need for POTWs 

to have a clear understanding of the source of the waste because applicable standards can be based on the 

origin of that waste. 

Another potential problematic waste is that from remedial site cleanup operations. Groundwater 

contaminated with gasoline or diesel fuel is by far the most common type of waste from those operations. 

While the wastes can contain flammable and toxic compounds (e.g., benzene and toluene), another 

concern is that large volumes of the waste at a small POTW can actually flush the treatment plant, thereby 

interfering with treatment operations. Similar concerns also exist for landfill leachate, another commonly 

hauled wastestream. Remedial wastes can also come from Comprehensive Environmental Response, 

Compensation, and Liability Act (CERCLA) sites, also known as Superfund sites. For CERCLA 

guidance, refer to EPA’s 1990 CERCLA Site Discharges to POTWs Guidance Manual.

Other concerns for POTWs that accept hauled wastes include the following: 

 Illegal dischargers could be discharging toxic pollutants that can pass through or interfere 

with the POTW operations. 

 Grease trap wastes can coat and inhibit POTW treatment equipment. 

 Local limits might not have accounted for pollutant loading or the variability of certain 

pollutants in hauled wastes. 

 Hauled wastes could contain pollutants for which local limits do not exist, and thus the 

effects of the waste are not readily identifiable. 

 Hauled wastes could be unmixed or highly concentrated. 

For more information on the acceptance of hazardous waste at POTWs, refer to EPA’s June 1987 

Guidance Manual for the Identification of Hazardous Wastes Delivered to Publicly Owned Treatment 

Works by Truck, Rail, or Dedicated Pipe. 
Chapter 7. Pollution Prevention 

Introduction to the National Pretreatment Program 7-1 

5. 

CHAPTER 7. 

POLLUTION PREVENTION

One of the objectives of the National Pretreatment Program is to improve opportunities to recycle 

and reclaim municipal and industrial wastewaters and sludges (40 CFR 403.2(c)). Recycling and 

reclamation are forms of pollution prevention (P2). P2 is the practice of reducing or eliminating waste at 

the source by modifying production processes, promoting the use of nontoxic or less-toxic substances, 

implementing conservation techniques, and reusing materials rather than putting them into the 

wastestream.15 P2 addresses all aspects of production processes—from raw material usage and inventory 

procedures to waste management and utilities conservation. Management techniques that incorporate P2 

reduce or eliminate the generation of pollutants, wastes, and adverse ecological impacts through new 

approaches, material substitutions, and optimizing processes and operating procedures. 

The Pollution Prevention Act of 1990 (PPA) established P2 as a national objective. The PPA 

equates P2 with source reduction, which it defines as “any practice [that] reduces the amount of any 

hazardous substance, pollutant, or contaminant entering any wastestream or otherwise released into the 

environment (including fugitive emissions) prior to recycling, treatment, or disposal, and reduces the 

hazards to human health and the environment associated with the release.”16 In defining P2, EPA has 

clarified that in-process recycling might qualify as P2, that P2 approaches can be applied to all pollutiongenerating activities—including those found in the energy, agricultural, federal, consumer, and industrial 

sectors—and that energy and water efficiency and conservation practices that reduce the creation of 

pollutants conform to the PPA’s definition of source reduction.17 Subsequently, Executive Orders 

likewise define energy and water efficiency/conservation as within the definition of source reduction and 

P2. 

The PPA established a P2 hierarchy as national policy, declaring that 

 Pollution should be prevented or reduced at the source. 

 Pollution that cannot be prevented should be recycled in an environmentally safe manner. 

 

15 EPA P2 website at www.epa.gov/p2. 16 42 U.S.C. chapter 133, section 13102 (5). 

17 P2 Policy Statement. http://www.epa.gov/p2/pubs/p2policy/policy.htm. 

Chapter 7. Applicable EPA Guidance 

Guides to Pollution Prevention: Municipal Pretreatment Program (EPA/625/R-93/006) 

NPDES Compliance Inspection Manual (EPA July 2004) 

Guide to Industrial Assessments for Pollution Prevention and Energy Efficiency (EPA-625-C-99-003) 

Why Should You Care About Preventing Waste: Pollution Prevention Pocketbook (EPA-742-E-01-001) 

Introduction to Pollution Prevention: Training Manual (EPA-742-B-95-003) 

Pollution Prevention at POTWs Case Studies (EPA 742-F-94-001) 

Ensuring a Sustainable Future: An Energy Management Guidebook for Wastewater and Water Utilities (EPA January 

2008) 
Chapter 7. Pollution Prevention 

 Pollution that cannot be prevented or recycled should be treated in an environmentally safe 

manner. 

 Disposal or other release into the environment should be employed as a last resort only and 

should be conducted in an environmentally safe manner. 

The PPA also directs EPA to integrate P2 concepts fully into all of its regulatory programs. EPA activities 

to promote and integrate P2 across all media programs include the following: 

 Coordinating development of regulations that will help to identify the potential for 

multimedia prevention strategies and that reduce end-of-pipe compliance costs. 

 Examining the use of P2 in enforcement actions and negotiations. P2 can be incorporated 

into environmental enforcement settlements through P2 supplemental environmental 

projects, which are environmentally beneficial projects that a company agrees to undertake 

when settling an enforcement action. 

 Working with state and local governments and trade associations to promote P2 among 

small- and medium-size businesses that often lack the capital to make changes. 

 Investing in outside programs, usually at the state level, by providing grant funds for 

reducing target chemicals from agricultural and transportation industries, and others. 

 Providing the scientific and technical knowledge necessary to implement P2 initiatives on 

a cross-media basis. 

In February 2010, EPA released its 2010–2014 

Pollution Prevention Program Strategic Plan. Figure 7-1 

presents the broad mission of EPA’s P2 Program. The P2 

Program’s strategy over the next 5 years is to identify and 

leverage pollution prevention opportunities to help reduce 

the emission of greenhouse gasses, the use of hazardous 

materials, and the use of natural resources, while 

contributing to a greener and more sustainable economy. In 

addition, the Plan includes an appendix that describes the 

P2 Program’s 5-year strategy for each of five sector areas: Chemicals and Manufacturing Industries, 

Hospitality, Electronics, Building and Construction, and Municipalities and Institutions. Figure 7-2 lists 

EPA’s P2 goals from the 2010–2014 Pollution Prevention Program Strategic Plan. 

The broad mission of EPA’s P2 Program is to 

prevent pollution at the source, promote the use of 

greener substances, and conserve natural 

resources, which are critical steps towards achieving 

a sustainable society. 

Figure 7-1. EPA’s P2 mission (from 

2010–2014 Strategic Plan). 

Goal 1: Reduce the generation of greenhouse gas emissions to mitigate climate change. 

Goal 2: Reduce the manufacture and use of hazardous materials to improve human and ecological health. 

Goal 3: Reduce the use of water and conserve other natural resources to protect ecosystems. 

Goal 4: Create business efficiencies that derive economic benefits and improve environmental performance. 

Goal 5: Institutionalize and integrate pollution prevention practices through government services, policies, and 

initiatives. 

Figure 7-2. EPA’s P2 goals (from 2010–2014 Strategic Plan). 

7-2 Introduction to the National Pretreatment Program 
Chapter 7. Pollution Prevention 

P2 AND THE PRETREATMENT PROGRAM

POTW personnel have many opportunities to encourage industries to adopt P2 measures. More 

than any other public authority, POTWs maintain close contact with local IUs and have an understanding 

of the IUs’ specific industrial process operations and wastestreams. 

Source reduction is an inherent element of the National Pretreatment Program. The program is 

designed to prevent toxic pollutants from being discharged to POTWs through controls on the IUs that 

discharge the pollutants. Thus, P2 could be considered an extension of current pretreatment program 

implementation activities. For example, pretreatment programs have the authority to require and enforce 

IU management practices to ensure that the POTW meets its NPDES permit requirements and to prevent 

interference with its POTW treatment facilities. POTWs are already involved in promoting P2 by 

requiring IUs to reduce pollutants in the wastestream before discharging to the POTW. By further 

integrating P2 concepts into existing pretreatment program activities, POTW personnel can help industrial 

and commercial facilities identify P2 opportunities, encourage them to assess the opportunities in greater 

detail, and, in general, heighten their awareness of P2 as another means of meeting their permit 

requirements. Pretreatment program implementation tools available to make P2 a more integral part of a 

pretreatment program are presented in figure 7-3. 

 IU Permits. Where local regulations allow, information about P2 measures and plans may be obtained as part of 

the permit application process. Also, where authorized a permittee may be required to perform a P2 assessment 

or develop a P2 plan (or both) as a condition of the permit. In issuing IU permits, POTWs may also require slug 

control plans, compliance schedules for improved operation and maintenance procedures, spill-prevention plans 

and TOMPs, and BMP conditions in the permits. 

 Inspections. POTW personnel are usually quite familiar with processes performed at their local industrial 

facilities and have exposure to a variety of industries performing the same or similar processes; therefore, they 

can easily disseminate nonconfidential information about actual P2 measures implemented and identify new P2 

opportunities. 

 Local limits. POTWs near or above MAHLs may institute P2 programs for their users to reduce specific 

pollutants. 

 Enforcement negotiations. A P2 audit may be required through a consent or compliance order, or 

implementation of P2 measures may be required as part of a settlement. 

 Outreach. POTWs can develop and disseminate information about P2 opportunities and success stories to IUs 

and the public. POTWs can hold workshops for IUs and disseminate information at public gatherings, such as 

Earth Day festivals. 

Figure 7-3. Pretreatment program P2 implementation tools. 

A P2 measure often employed by POTWs is requiring dental offices to switch from using 

mercury amalgams to alternative types of amalgams to reduce the discharge of mercury before the 

discharge enters the wastestream. Another P2 measure is encouraging industrial laundries to switch to 

alternative detergents that have lower levels of phosphates and endocrine-disrupting chemicals such as 

alkylphenol ethoxylates, which are common constituents in some detergents. Also, water and heat/energy 

conservation has been achieved at industrial laundries by reconfiguring some of the rinse cycles. Many 

healthcare facilities previously using film-generating X-ray and magnetic resonance imaging technology 

have now converted to digital imagery, eliminating wastewater-generating processes entirely. Another 

example of P2 at IUs is dry sweeping process area floors before they are washed. 

Many POTWs have also implemented fats, oils, and grease (FOG) programs to prevent blockages 

in the sewer system, primarily caused by grease buildup from restaurants. FOG programs promote 

educating the public about how pouring fats, oils, and greases down the drain can harm the POTW and 

the environment. Restaurants can also train restaurant employees to wipe down cookware before putting it 

in the dishwasher and wipe up FOG before mopping with water. Effective FOG programs include 

Introduction to the National Pretreatment Program 7-3 
Chapter 7. Pollution Prevention 

enforcement authority for the POTWs. Increasingly, federal pretreatment regulations are incorporating P2 

measures. The Pretreatment Standards for the Transportation Equipment Cleaning Industry, for example, 

include a regulatory alternative to numeric effluent limits based on a pollutant management plan and a 

low-flow exclusion to encourage water conservation and reuse. 

KEY ELEMENTS OF A SUCCESSFUL POTW P2 PROGRAM

Although P2 activities can be unique to each POTW, the following are key elements of successful 

P2 programs: 

 Integrate P2 into existing activities. POTWs that view P2 as an enhancement (instead of 

an additional requirement) to their existing pretreatment programs modify their existing 

pretreatment activities efficiently and effectively. 

 Start small. POTWs that slowly phase in new P2 activities overcome impediments such as 

limited resources and resistance. Small changes (such as dry sweeping the process area floor 

before washdown, or switching to environmentally friendly detergents or lubricants) can be 

implemented gradually with minimal resources. Such an approach enables P2 activities to 

become an accepted integral part of the pretreatment program. 

 Define attainable goals and measure success. Short-term, narrowly focused efforts have a 

greater chance of succeeding. For example, POTWs have targeted a specific pollutant and 

group of industries, established specific P2 activities, and monitored the progress and 

success of those activities. With each new success recorded, the benefits of P2 are 

illustrated, and resistance to change might be overcome by the demand for further success. 

 Provide incentives. Incentives are effective tools for persuading users to investigate P2 

opportunities. POTWs have used a wide range of tools, such as publicly recognizing P2 

achievements and reducing regulatory requirements. 

 Train POTW field personnel. POTW inspectors that are knowledgeable about P2 

opportunities can work closely with IUs to encourage them to implement P2. Cross-media 

training of POTW staff about P2 opportunities in all media (e.g., water, stormwater, air, 

solid waste) provides that much more opportunity for POTW personnel to notice and 

promote P2 opportunities. 

 Learn from others. A vast amount of information has been acquired and compiled about 

practical implementation of P2 measures. Conduct research on the Internet, and use other 

resources to learn more about P2 measures applicable to specific circumstances. Showing 

managers case studies and cost savings realized with P2 measures can gain management 

support of P2 programs. EPA provides grant monies for researching P2 opportunities and 

makes the reports available to the public. For more detail on this program, see 

http://www.epa.gov/p2/pubs/grants/index.htm. 

BENEFITS OF P2 FOR POTWS

P2 offers substantial benefits to POTWs. By incorporating P2 into pretreatment programs and 

reducing the quantity and toxicity of user discharges, P2 can help POTWs 

 Meet federal and state environmental quality standards, including sludge disposal 

requirements, current or future toxic air emission requirements, and NPDES permit 

requirements 

 Reduce influent pollutant loadings and wastewater flows to POTWs, resulting in lower 

operation and maintenance costs and reduced or eliminated need for capital expenditures 

7-4 Introduction to the National Pretreatment Program 
Chapter 7. Pollution Prevention 

 Improve biosolids quality through reduced loadings of heavy metals and refractory 

organics 

 Realize energy, chemical, and sludge management savings because of reduced wastewater 

treatment needs 

 Reduce the transfer of influent contaminants from one environmental medium (e.g., 

wastewater) to others (e.g., land, surface and groundwater, and air) 

 Increase POTW personnel safety and reduce collection system hazards from toxic or 

hazardous gases 

 Further reduce the occurrences of interference and pass through 

 Enable continued or expanded growth in the community without harm to the environment 

 Improve public image 

 Reduce future liabilities. 

BENEFITS OF P2 FOR IUS

Industrial and commercial facilities also can benefit from P2. In many cases, P2 might be the least 

expensive means of reducing unacceptable toxic discharges. Pretreatment personnel can point out the 

benefits of P2 to their sewer users. Through P2, IUs can 

 Achieve compliance with pretreatment program requirements 

 Minimize emissions to all media and reduce water consumption 

 Reduce wastewater monitoring, treatment, and disposal costs 

 Reduce raw-material use, feedstock purchases, and manufacturing costs 

 Reduce operation and maintenance costs 

 Increase productivity and manufacturing efficiency and reduce off-specification products 

 Reduce regulatory compliance costs 

 Reduce hazards to employees through exposure to chemicals 

 Reduce costs of environmental impairment insurance 

 Improve public image and employee morale 

 Reduce potential liability associated with toxic waste 

 Decrease regulatory requirements by eliminating the need for permits, hazardous waste 

manifests, monitoring, and reporting. 

Figure 7-4 summarizes the types of activities IU can implement to realize P2 benefits at their 

facility. 

Figure 7-4. Types of P2 activities IUs can implement.

 Improve housekeeping, maintenance, training, or inventory control 

To realize P2 benefits industrial facilities can 

 Modify equipment or technology 

 Modify process or procedure 

 Reformulate or redesign products 

 Substitute raw materials 

Introduction to the National Pretreatment Program 7-5 
Chapter 7. Pollution Prevention 

7-6 Introduction to the National Pretreatment Program 

WATER CONSERVATION AS P2 

One important form of P2 is water conservation. Some of the main drivers of water conservation 

practices are (1) the economic considerations that result from higher operating costs of using more water 

(e.g., increased water bills and wastewater treatment costs, pumping costs, wastewater sludge generation 

and disposal costs) and (2) water source restrictions (e.g., widespread regional droughts, increasing water 

demands of urban populations). Cost savings also include decreasing the energy needed to heat or chill 

water and reducing or delaying the need for wastewater treatment capacity expansion. (For more 

information on energy conservation, refer to Ensuring a Sustainable Future: Energy Management 

Guidebook for Wastewater and Water Utilities, EPA, January 2008 

(http://www.peercenter.net/ewebeditpro/items/O73F22367.pdf). 

The cost savings realized from implementing water reuse18 and reduction technologies and P2 

practices can be significant. The monetary savings of implementing water-conservation measures can be 

substantial, with payback periods often measured within a few months or years. They are compelling 

reasons for IUs to consider enhancing their water-conservation efforts. Furthermore, encouraging 

nondomestic users to reconfigure industrial operations to eliminate process wastewaters altogether (zero 

discharge) assists in meeting the ultimate goal of the Clean Water Act to restore and maintain the 

chemical, physical, and biological integrity of the nation's waters. 

EPA’s ELG rulemaking records identify when water-conservation practices are being used in 

existing industrial processes. The rulemaking process compares and contrasts treatment and cost 

efficiency for a variety of treatment options per industrial sector. The findings support that, for a variety 

of industrial sectors with well-designed and operated on-site treatment systems, the systems are more 

efficient at treating and removing pollutants from wastewater when the wastewater is more highly 

concentrated. That is because wastewater treatment technologies operating within their design 

specifications are limited solely by the physical/chemical properties of the pollutants in the wastewater, 

not necessarily by influent concentrations. Flow reduction generally increases the pollutant concentrations 

to on-site wastewater treatment systems, thereby increasing the efficiency of the wastewater treatment 

system.19 Consequently, a properly managed wastewater treatment system operating within its design 

specifications can produce a consistent effluent despite fluctuations or increases in influent concentration. 

EPA also notes that implementing water-conservation measures requires a systematic approach 

because changes in industrial processes could require adjustments in downstream operations. The water 

systems of many plants are already complex as a result of plant changes and improvements to existing 

systems. Isolated attempts to reuse water or change the water system are often stop-gap solutions that can 

cause more problems in the long term and even lead to unexpected or undesirable surprises in plant 

operations. Therefore, water management strategies, industrial water reclamation technologies, and a 

systematic approach to using them are necessary if plant-wide water reuse and effluent discharge 

reduction goals are to be reached. 

A number of new tools are available for implementing water-conservation measures through a 

systematic approach, e.g., water-pinch technology and mathematical optimization. Such tools seek to 

identify a pinch point, called the freshwater pinch, on the basis of a key contaminant’s concentration. 

Within a given process plant, water-using operations that can tolerate contaminant levels above that 

concentration do not require freshwater; they can instead reuse water streams from elsewhere in the 

process. Analogously, plant water streams with contaminant levels below that pinch concentration do not 

 

18 U.S. Environmental Protection Agency, Guidelines for Water Reuse (September 2004), 

http://www.epa.gov/ORD/NRMRL/pubs/625r04108/625r04108.htm. 19 W. Wesley Eckenfelder, Industrial Water Pollution Control, McGraw-Hill, Inc., New York (1989), p. 60. 
Chapter 7. Pollution Prevention 

Introduction to the National Pretreatment Program 7-7 

need to be sent for disposal but can be reused elsewhere in the plant. Using that information, system 

designers and retrofitters can maximize water reuse and minimize wastewater generation on-site.20 For 

example, segregating processes wastewaters for pretreatment of that key contaminant or decentralized 

water reuse can reduce costs and simplify and improve the performance of end-of-pipe wastewater 

treatment and reuse by avoiding cross-contamination by difficult-to-treat chemical compounds.21

POTENTIAL IMPEDIMENTS TO P2 

Although the numerous benefits make pursuing P2 attractive, implementing source reduction 

might not be possible in some situations. Before implementing a P2 practice, the benefits and barriers of 

the potential opportunity must be evaluated. Any such change could be met with resistance because of 

institutionalized practice. Common impediments could arise in any of the following categories: 

 Technology 

– Decrease in product quality. 

– Unable to change raw materials because of available technology or contractual 

requirements. 

 Financial 

– Potentially high costs associated with implementing alternatives (i.e., new equipment or 

materials, or personnel and training) without examining the cost’s rate of return. 

– Losses from downtime during switchovers and startups. 

– Foreign competitors might have an economic advantage if they are not obligated to 

comply with U.S. regulations. 

– Binding contracts with existing waste haulers and treatment, storage and disposal 

facilities may exist. 

 Organizational 

– Lack of or poor communication between persons who possess the knowledge and ideas 

for improvements and those who can actually implement the changes. 

– Limited personnel or internal resources available to investigate or make changes. 

– Lack of coordination and cooperation among divisions in the corporation. 

 Behavioral 

– Personnel might consider alternatives as inconvenient (e.g., dry sweeping followed by a 

washdown as opposed to a washdown alone). 

– Companies might be skeptical of the benefits or might be unwilling or unable to invest 

the necessary funds. 

– POTW personnel might have difficulty persuading municipal officials that activities 

promoting P2 are integral to meeting the goals of the local pretreatment program. POTW 

personnel might also have to educate officials and managers that funding for P2 

initiatives is needed to meet the program goals and that doing so might lead to significant 

returns on investment. 

 

20 Y.A. Liu, Bruce Lucas, and James G. Mann, Up-to-date Tools for Water-System Optimization, Chemical Engineering

(January 2004). 

21 B. Durham and L. Patria, Wastewater: A Reliable Water Resource, Chemical Engineering (October 2006).
Chapter 7. Pollution Prevention 

 Regulatory 

– Concentrating a pollutant for recycling could classify it as a hazardous waste (e.g., 

silver). Consequently, an IU could choose to discharge the pollutant rather than be 

subject to regulations regarding the handling, treatment, and disposal of a hazardous 

waste. However, concentrating wastewaters generally reduces treatment costs and might 

enable the IU to recover its costs (e.g., recovery of silver through electrowinning). 

– POTWs might need to expand their authority to incorporate P2 planning or other P2 

requirements into permitting and enforcement actions. 

P2 ASSISTANCE

EPA, states, industry trade associations, and university technology transfer and outreach 

departments provide P2 information through direct technical assistance, training courses, and a variety of 

publications. For more information on POTWs integrating P2 into their pretreatment programs, refer to 

EPA’s 1993 Guides to Pollution Prevention—Municipal Pretreatment Programs and the 2004 NPDES 

Compliance Inspection Manual. Specific industry trade associations and university technology transfer 

and outreach departments are usually aware of P2 assistance materials, specific P2 opportunities, and the 

costs and success of implementing them. Some further sources that disseminate P2 information follow: 

 EPA’s Pollution Prevention (P2) website. Provides general information about P2 policies 

and programs, P2 technical assistance information, case studies, and P2 resources. The 

annual Pollution Prevention Grant Programs information is also featured on the site. See 

http://www.epa.gov/p2/index.htm and Pollution Prevention at POTWs, Case Studies

(winter 1994) at http://www.epa.gov/p2/pubs/potw.pdf. 

 Pollution Prevention Information Clearinghouse. A free information service dedicated to 

reducing and eliminating industrial pollutants through technology transfer, source 

reduction, education, and public awareness. See http://www.epa.gov/oppt/ppic. 

 State programs. Provide technical assistance to conduct P2 assessments, develop guidance 

manuals on conducting these assessments; actually conduct these assessments; provide 

assistance in developing P2 plans for all the POTW’s users; provide training for industry, 

state, and POTW personnel; and offer grants for P2 projects. 

 National Institute of Standards and Technology (NIST). An office of the U.S. 

Department of Commerce that develops technology to improve product quality, modernize 

manufacturing processes, ensure product reliability, and facilitate rapid commercialization 

of products that are based on new scientific discoveries. You can search the NIST websites 

(www.nist.gov) for different industry sectors. 

 EPA technical support documents. EPA’s technical support documents 

(http://www.epa.gov/guide/plan.html) and records supporting EPA’s biennial ELG 

program plans also provide useful information. They provide a sample of the current 

limitation and latest developments in industrial pollutant prevention, water conservation, 

and wastewater treatment. The technical support documents also identify the industrial 

sectors not regulated by effluent guidelines. 

 Design for the Environment publications. EPA is working with individual industry 

sectors to compare and improve the performance and human health and environmental 

risks and costs of existing and alternative products, processes, and practices 

(http://www.epa.gov/dfe/pubs). 

 EPA National Service Center for Environmental Publications (NSCEP). The NSCEP 

maintains and distributes EPA publications in hard copy, CD-ROM, and other multimedia 

7-8 Introduction to the National Pretreatment Program 
Chapter 7. Pollution Prevention 

formats. NSCEP also develops and distributes the annual EPA National Publications 

Catalog. The website allows users to search the catalog for P2 documents and other related 

topics. Order documents online or through the Government Printing Office, as described 

below (http://www.epa.gov/nscep). Note that you must have the EPA publication number 

or title of the document available when ordering. 

 Industry sector notebooks. EPA's Office of Compliance has developed a series of profiles 

or “notebooks” containing information on selected major industries, including dry 

cleaning, printing, and wood furniture. Each notebook provides comprehensive industrial 

process information, regulatory requirements, and P2 techniques. View the documents 

online or order printed copies for a fee (between $6 and $25 depending on length) from the 

Government Printing Office by calling (202) 512-1800 

(http://www.epa.gov/Compliance/resources/publications/assistance/sectors/notebooks/inde

x.html#industry). 

 Association websites. Many associations, including industrial sector associations, provide 

training and information related to P2. Examples are the California Water Environment 

Association (http://cwea.org/p3s) and the Water Environment Federation 

(http://www.wef.org). 

In addition to getting the available information about P2, IUs can become involved in several 

EPA voluntary programs. Information on these programs is available from the Office of Pollution 

Prevention and Toxics: 

 Design for the Environment. A voluntary partnership program that helps businesses 

design or redesign products, processes, and management systems that are cleaner, more 

cost-effective, and safer for workers and the public. 

 Environmental Labeling. Covers a broad range of activities from business-to-business 

transfers of product-specific environmental information to environmental labeling in retail 

markets. Provides an opportunity to inform consumers about product characteristics that 

might not be readily apparent and guide their use in an environmentally beneficial manner. 

 Environmentally Preferable Purchasing. A federal government-wide program managed 

by the EPA Office of Pollution Prevention and Toxics (OPPT) that requires and helps 

executive agencies to purchase environmentally preferable products and services. 

 Electronic Product Environmental Assessment Tool. A procurement tool to help 

institutional purchasers in the public and private sectors evaluate, compare, and select 

desktop computers, notebooks and monitors on the basis of their environmental attributes. 

 Green Chemistry. An initiative under OPPT’s DfE program that focuses on P2 through the 

environmentally conscious design of chemical products and processes. 

 Green Engineering. An initiative under the DfE program designed to promote the 

development and commercialization of environmentally beneficial design methods, riskbased design tools, and green technologies through education, outreach, and partnering 

with the academic, research, and industrial communities. 

 Green Suppliers Network. A collaborative venture between industry and EPA that works 

with all levels of the manufacturing supply chain to achieve environmental and economic 

benefits, improve performance, minimize waste generation, and remove institutional 

roadblocks through its innovative approach to leveraging a national network of 

manufacturing technical assistance resources. 

Introduction to the National Pretreatment Program 7-9 
Chapter 7. Pollution Prevention 

7-10 Introduction to the National Pretreatment Program 

 Hospitals for a Healthy Environment (H2E). A voluntary program working with the 

healthcare industry to reduce its environmental impact. In 2006 this program became 

EPA’s first voluntary program to become an independent nonprofit organization. 

 Sustainable Futures. A pilot project designed to encourage industry to use EPAdeveloped chemical risk screening tools and P2 principles in making decisions about new 

chemicals at the research and development stage before submittal as premanufacture 

notices. 

 Suppliers Partnership for the Environment. A trade association composed of small, midsized, and large automotive and vehicle suppliers that are working in partnership with EPA 

to create new and innovative business-centered approaches to environmental protection 

that improve the environment while providing value to the participants.22

For additional information on these voluntary pollution programs, see EPA’s P2 website at 

www.epa.gov/p2. 

One of the ways EPA promotes P2 is by supporting the development of a network of state and 

tribal P2 programs. The OPPT P2 Grant Program, created under the authority of the PPA, provides 

matching funds to states and tribes to support P2 activities and develop state programs. The majority of 

the P2 grants fund projects in the areas of technical assistance and training, education and outreach, 

regulatory integration, data collection and research, demonstration projects, and recognition programs. 

Additional information on OPPT’s grant programs that promote P2 activities is at 

http://www.epa.gov/p2/pubs/grants/index.htm. 

 

22 Overview: Office of Pollution Prevention and Toxics Programs (January 2007).

http://www.epa.gov/oppt/pubs/oppt101c2.pdf.