Wastewater industrial pretreatment study guide
The General Pretreatment Regulations in 40 CFR Part 403 apply to pollutants from non-domestic sources covered by Pretreatment Standards that are introduced into POTWs, to POTWs that receive wastewater from sources subject to National Pretreatment Standards, to States that have or are applying for approved NPDES programs and to new or existing sources subject to Pretreatment Standards. This guide sets out what the federal rule text states on key definitions, the general and specific prohibitions and local limits, categorical standards, POTW pretreatment program requirements, Industrial User and POTW reporting, recordkeeping, and the upset and bypass provisions. Many duties fall on a specific party (the POTW, the Control Authority, the Approval Authority or the Industrial User) and carry "except" or "unless" conditions, so each point keeps them. Your State program and your facility's permit may have their own requirements, so check them too. Every point links to the regulation and quotes its exact words.
Scope and key definitions
Part 403 sets out the responsibilities of Federal, State and local government, industry and the public for National Pretreatment Standards that control pollutants which pass through or interfere with POTW treatment processes or which may contaminate sewage sludge.
“It establishes responsibilities of Federal, State, and local government, industry and the public to implement National Pretreatment Standards to control pollutants which pass through or interfere with treatment processes in Publicly Owned Treatment Works (POTWs) or which may contaminate sewage sludge.”
Part 403 applies to any new or existing source subject to Pretreatment Standards, but National Pretreatment Standards do not apply to sources that discharge to a sewer not connected to a POTW Treatment Plant.
“To any new or existing source subject to Pretreatment Standards. National Pretreatment Standards do not apply to sources which Discharge to a sewer which is not connected to a POTW Treatment Plant.”
The Control Authority is the POTW if its Pretreatment Program Submission has been approved under 403.11, or the Approval Authority if the Submission has not been approved.
“The term Control Authority refers to: (1) The POTW if the POTW's Pretreatment Program Submission has been approved in accordance with the requirements of § 403.11; or (2) The Approval Authority if the Submission has not been approved.”
Interference is a Discharge that, alone or with other discharges, both 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 or prevents sewage sludge use or disposal in compliance with the listed statutory provisions and regulations or permits issued under them (or more stringent State or local regulations).
“The term Interference means a Discharge which, 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 the following statutory provisions and regulations or permits issued thereunder (or more stringent State or local regulations):”
Pass Through is a Discharge that exits the POTW into waters of the United States in quantities or concentrations that, alone or with other discharges, cause a violation of any requirement of the POTW's NPDES permit.
“The term Pass Through means a Discharge which 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).”
A New Source is a building, structure, facility or installation from which there is or may be a Discharge, whose construction began after proposed Pretreatment Standards under section 307(c) were published that will apply to it if those Standards are later promulgated, provided that one of the listed conditions is met; the first option is that it is built at a site at which no other source is located.
“The term New Source means any building, structure, facility or installation from which there is or may be a Discharge of pollutants, the construction of which commenced after the publication of proposed Pretreatment Standards under section 307(c) of the Act which will be applicable to such source if such 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”
Except as provided in 403.3(v)(2) and (v)(3), every Industrial User subject to Categorical Pretreatment Standards is a Significant Industrial User.
“Except as provided in paragraphs (v)(2) and (v)(3) of this section, the term Significant Industrial User means: (i) All Industrial Users subject to Categorical Pretreatment Standards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N; and”
Subject to the same exceptions in 403.3(v)(2) and (v)(3), any other Industrial User is also a Significant Industrial User if it meets one of the options: an average of 25,000 gallons per day or more of process wastewater (excluding sanitary, noncontact cooling and boiler blowdown wastewater), a process wastestream of 5 percent or more of the POTW Treatment plant's average dry weather hydraulic or organic capacity, or designation by the Control Authority on the basis that it has a reasonable potential for adversely affecting the POTW's operation or for violating any Pretreatment Standard or requirement.
“Any other Industrial User that: discharges an average of 25,000 gallons per day or more of process wastewater to the POTW (excluding sanitary, noncontact cooling and boiler blowdown wastewater); contributes a process wastestream which 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 Control Authority on the basis that the Industrial User 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)).”
The Control Authority may find that a categorical Industrial User is a Non-Significant Categorical Industrial User rather than a Significant Industrial User if it never discharges more than 100 gallons per day of total categorical wastewater (excluding sanitary, non-contact cooling and boiler blowdown wastewater, unless specifically included in the Pretreatment Standard) and the listed conditions are met.
“The Control Authority may determine that an Industrial User subject to categorical Pretreatment Standards under § 403.6 and 40 CFR chapter I, subchapter N is a Non-Significant Categorical Industrial User rather than a Significant Industrial User on a finding that the Industrial User never discharges more than 100 gallons per day (gpd) of total categorical wastewater (excluding sanitary, non-contact cooling and boiler blowdown wastewater, unless specifically included in the Pretreatment Standard) and the following conditions are met:”
On a finding that an Industrial User meeting the 403.3(v)(1)(ii) criteria has no reasonable potential for adversely affecting the POTW's operation or for violating any Pretreatment Standard or requirement, the Control Authority may at any time, on its own initiative or in response to a petition from an Industrial User or POTW, determine that it is not a Significant Industrial User.
“Upon a finding that an Industrial User meeting the criteria in paragraph (v)(1)(ii) of this section has no reasonable potential for adversely affecting the POTW's operation or for violating any Pretreatment Standards or requirement, the Control Authority may at any time, on its own initiative or in response to a petition received from an Industrial User or POTW, and in accordance with 40 CFR 403.8(f)(6), determine that such Industrial User is not a Significant Industrial User.”
Not covered here
The Part 403 objectives (403.2) and the State or local law provision (403.4) are not covered here. Removal credits (403.7), State program approval (403.9 to 403.11), fundamentally different factors variances (403.13), confidentiality (403.14), net/gross credits (403.15) and program modification (403.18) are not covered here. We only write what an official source states, so study these parts with your certifying program's materials.
Prohibited discharges and local limits
A User may not introduce into a POTW any pollutant that causes Pass Through or Interference. The general and specific prohibitions apply to each User, whether or not it is subject to other pretreatment standards or requirements.
“A User may not introduce into a POTW any pollutant(s) which cause Pass Through or Interference. These general prohibitions and the specific prohibitions in paragraph (b) of this section apply to each User introducing pollutants into a POTW whether or not the User is subject to other National Pretreatment Standards or any national, State, or local Pretreatment Requirements.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Pollutants that create a fire or explosion hazard in the POTW are prohibited, including wastestreams with a closed cup flashpoint of less than 140 °F (60 °C) using the test methods in 40 CFR 261.21. Pollutants that will cause corrosive structural damage to the POTW are prohibited, and Discharges with pH lower than 5.0 are prohibited in every case unless the works is specifically designed to accommodate them.
“Pollutants which create a fire or explosion hazard in the POTW, including, but not limited to, wastestreams with a closed cup flashpoint of less than 140 degrees Fahrenheit or 60 degrees Centigrade using the test methods specified in 40 CFR 261.21; (2) Pollutants which will cause corrosive structural damage to the POTW, but in no case Discharges with pH lower than 5.0, unless the works is specifically designed to accommodate such Discharges;”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Solid or viscous pollutants in amounts that will obstruct flow in the POTW resulting in Interference are prohibited, as is any pollutant, including oxygen demanding pollutants (BOD, etc.), released at a flow rate and/or concentration that will cause Interference with the POTW.
“Solid or viscous pollutants in amounts which will cause obstruction to the flow in the POTW resulting in Interference; (4) Any pollutant, including oxygen demanding pollutants (BOD, etc.) released in a Discharge at a flow rate and/or pollutant concentration which will cause Interference with the POTW.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Heat may not be introduced in amounts that inhibit biological activity and cause Interference, and in no case so that the POTW Treatment Plant temperature exceeds 40 °C (104 °F), unless the Approval Authority, on the POTW's request, approves alternate temperature limits.
“Heat in amounts which 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 40 °C (104 °F) unless the Approval Authority, upon request of the POTW, approves alternate temperature limits.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Petroleum oil, nonbiodegradable cutting oil or products of mineral oil origin in amounts that will cause interference or pass through are prohibited, as are pollutants that produce toxic gases, vapors or fumes within the POTW in a quantity that may cause acute worker health and safety problems. Trucked or hauled pollutants are prohibited except at discharge points the POTW designates.
“Petroleum oil, nonbiodegradable cutting oil, or products of mineral oil origin in amounts that will cause interference or pass through; (7) Pollutants which result in the presence of toxic gases, vapors, or fumes within the POTW in a quantity that may cause acute worker health and safety problems; (8) Any trucked or hauled pollutants, except at discharge points designated by the POTW.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Each POTW developing a Pretreatment Program under 403.8 must develop and enforce specific limits to implement the prohibitions, and each POTW with an approved program must keep developing them as necessary and enforce them effectively.
“Each POTW developing a POTW Pretreatment Program pursuant to § 403.8 shall develop and enforce specific limits to implement the prohibitions listed in paragraphs (a)(1) and (b) of this section. Each POTW with an approved pretreatment program shall continue to develop these limits as necessary and effectively enforce such limits.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
All other POTWs (those not covered by 403.5(c)(1)) must, where pollutants contributed by Users result in Interference or Pass-Through and the violation is likely to recur, develop and enforce specific effluent limits for Industrial Users, and all other users as appropriate, which together with appropriate changes in the POTW Treatment Plant's facilities or operation are necessary to ensure renewed and continued compliance with the POTW's NPDES permit or sludge use or disposal practices.
“All other POTW's shall, in cases where pollutants contributed by User(s) result in Interference or Pass-Through, and such violation is likely to recur, develop and enforce specific effluent limits for Industrial User(s), and all other users, as appropriate, which, together with appropriate changes in the POTW Treatment Plant's facilities or operation, are necessary to ensure renewed and continued compliance with the POTW's NPDES permit or sludge use or disposal practices.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Specific effluent limits may not be developed and enforced without individual notice to persons or groups who asked for it and an opportunity to respond. POTWs may develop Best Management Practices (BMPs) to implement 403.5(c)(1) and (c)(2); such BMPs are considered local limits and Pretreatment Standards for the purposes of Part 403 and section 307(d) of the Act.
“Specific effluent limits shall not be developed and enforced without individual notice to persons or groups who have requested such notice and an opportunity to respond. (4) POTWs may develop Best Management Practices (BMPs) to implement paragraphs (c)(1) and (c)(2) of this section. Such BMPs shall be considered local limits and Pretreatment Standards for the purposes of this part and section 307(d) of the Act.”
40 CFR 403.5, National pretreatment standards: Prohibited discharges
Not covered here
The affirmative defenses in 403.5(a)(2), the local limits provision in 403.5(d) and EPA enforcement under 403.5(e) are not covered here; see the linked section. We only write what an official source states, so study these parts with your certifying program's materials.
Categorical Pretreatment Standards
An existing Industrial User that adds or changes a process that may be in a subcategory must request a category certification before discharging from it, and a New Source must request it before commencing discharge.
“If an existing Industrial User adds or changes a process or operation which may be included in a subcategory, the existing Industrial User must request this certification prior to commencing discharge from the added or changed processes or operation. A New Source must request this certification prior to commencing discharge.”
40 CFR 403.6, National pretreatment standards: Categorical standards
Existing sources must comply with categorical Pretreatment Standards within 3 years of the date the Standard is effective, unless a shorter time is specified in the applicable subpart.
“Compliance by existing sources with categorical Pretreatment Standards shall be within 3 years of the date the Standard is effective unless a shorter compliance time is specified in the appropriate subpart of 40 CFR chapter I, subchapter N.”
40 CFR 403.6, National pretreatment standards: Categorical standards
New Sources must install, have in operating condition and start up all required pollution control equipment before beginning to Discharge, and must meet all applicable Pretreatment Standards within the shortest feasible time, not to exceed 90 days.
“New Sources shall install and have in operating condition, and shall “start-up” all pollution control equipment required to meet applicable Pretreatment Standards before beginning to Discharge. Within the shortest feasible time (not to exceed 90 days), New Sources must meet all applicable Pretreatment Standards.”
40 CFR 403.6, National pretreatment standards: Categorical standards
Categorical limits apply to the effluent of the regulated process, or as otherwise specified by the standard.
“Limits in categorical Pretreatment Standards shall apply to the effluent of the process regulated by the Standard, or as otherwise specified by the standard.”
40 CFR 403.6, National pretreatment standards: Categorical standards
Except where expressly authorized by an applicable Pretreatment Standard or Requirement, no Industrial User may increase the use of process water or in any other way attempt to dilute a Discharge as a partial or complete substitute for adequate treatment. The Control Authority may impose mass limitations on Industrial Users that are using dilution to meet applicable Pretreatment Standards or Requirements, or in other cases where mass limitations are appropriate.
“Except where expressly authorized to do so by an applicable Pretreatment Standard or Requirement, no Industrial User shall ever increase the use of process water, or in any other way attempt to dilute a Discharge as a partial or complete substitute for adequate treatment to achieve compliance with a Pretreatment Standard or Requirement. The Control Authority may impose mass limitations on Industrial Users which are using dilution to meet applicable Pretreatment Standards or Requirements, or in other cases where the imposition of mass limitations is appropriate.”
40 CFR 403.6, National pretreatment standards: Categorical standards
Under the combined wastestream provisions (403.6(e)(4)), an Industrial User may change monitoring points only after receiving approval from the Control Authority, which must ensure the change does not let the User substitute dilution for adequate treatment.
“The Industrial User may change monitoring points only after receiving approval from the Control Authority. The Control Authority shall ensure that any change in an Industrial User's monitoring point(s) will not allow the User to substitute dilution for adequate treatment to achieve compliance with applicable Standards.”
40 CFR 403.6, National pretreatment standards: Categorical standards
Not covered here
The combined wastestream formulas themselves, the equivalent mass and concentration limit calculations in 403.6(c), and the category determination procedure in 403.6(a)(2) to (a)(5) are not reproduced here; see the linked section. We only write what an official source states, so study these parts with your certifying program's materials.
POTW pretreatment programs
A POTW (or POTWs run by the same authority) with total design flow greater than 5 mgd that receives pollutants from Industrial Users which Pass Through, Interfere or are otherwise subject to Pretreatment Standards must establish a program, unless the NPDES State assumes local responsibilities under 403.10(e).
“Any POTW (or combination of POTWs operated by the same authority) with a total design flow greater than 5 million gallons per day (mgd) and receiving from Industrial Users pollutants which Pass Through or Interfere with the operation of the POTW or are otherwise subject to Pretreatment Standards will be required to establish a POTW Pretreatment Program unless the NPDES State exercises its option to assume local responsibilities as provided for in § 403.10(e).”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
The Regional Administrator or Director may require a POTW with a design flow of 5 mgd or less to develop a program if he or she finds that circumstances such as the nature or volume of industrial influent, treatment process upsets, effluent violations or sludge contamination warrant it in order to prevent Interference with the POTW or Pass Through.
“The Regional Administrator or Director may require that a POTW with a design flow of 5 mgd or less develop a POTW Pretreatment Program if he or she finds that the nature or volume of the industrial influent, treatment process upsets, violations of POTW effluent limitations, contamination of municipal sludge, or other circumstances warrant in order to prevent Interference with the POTW or Pass Through.”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
Individual and general control mechanisms must be enforceable and contain at least the listed conditions, starting with a statement of duration of no more than five years.
“Both individual and general control mechanisms must be enforceable and contain, at a minimum, the following conditions: (1) Statement of duration (in no case more than five years);”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
The POTW must have authority and procedures, after informal notice to the discharger, to immediately and effectively halt or prevent any discharge that reasonably appears to present an imminent endangerment to the health or welfare of persons.
“The POTW shall have authority and procedures (after informal notice to the discharger) immediately and effectively to halt or prevent any discharge of pollutants to the POTW which reasonably appears to present an imminent endangerment to the health or welfare of persons.”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
The POTW must inspect and sample the effluent from each Significant Industrial User at least once a year, except as otherwise specified in 403.8(f)(2)(v)(A) to (C).
“Inspect and sample the effluent from each Significant Industrial User at least once a year, except as otherwise specified below:”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
The POTW must evaluate whether each Significant Industrial User needs a plan or other action to control Slug Discharges (Users identified as significant before November 14, 2005 had to be evaluated at least once by October 14, 2006; others within 1 year of being designated). A Slug Discharge is any non-routine, episodic Discharge, such as an accidental spill or non-customary batch Discharge, with a reasonable potential to cause Interference or Pass Through or otherwise violate the POTW's regulations, local limits or Permit conditions. Significant Industrial Users must notify the POTW immediately of facility changes affecting Slug Discharge potential.
“Evaluate whether each such Significant Industrial User needs a plan or other action to control Slug Discharges. For Industrial Users identified as significant prior to November 14, 2005, this evaluation must have been conducted at least once by October 14, 2006; additional Significant Industrial Users must be evaluated within 1 year of being designated a Significant Industrial User. For purposes of this subsection, a Slug Discharge is any Discharge of a non-routine, episodic nature, including but not limited to an accidental spill or a non-customary batch Discharge, which 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. The results of such activities shall be available to the Approval Authority upon request. Significant Industrial Users are required to notify the POTW immediately of any changes at its facility affecting potential for a Slug Discharge.”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
The POTW's procedures must provide for at least annual newspaper public notice of Industrial Users that were in significant noncompliance at any time during the previous 12 months.
“These procedures shall include provision for at least annual public notification in a newspaper(s) of general circulation that provides meaningful public notice within the jurisdiction(s) served by the POTW of Industrial Users which, at any time during the previous 12 months, were in significant noncompliance with applicable Pretreatment requirements.”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
The POTW must develop local limits as required in 403.5(c)(1), or demonstrate that they are not necessary, and must develop and implement an enforcement response plan.
“The POTW shall develop local limits as required in § 403.5(c)(1), or demonstrate that they are not necessary. (5) The POTW shall develop and implement an enforcement response plan.”
40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW
Not covered here
The full list of legal authorities and procedures in 403.8(f), the remaining significant noncompliance criteria, and program approval deadlines in 403.8(b) are not all repeated here; see the linked section. We only write what an official source states, so study these parts with your certifying program's materials.
Industrial User reports and notices
Existing Industrial Users subject to a categorical standard and currently discharging to or scheduled to discharge to a POTW must submit a baseline report to the Control Authority within 180 days after the standard's effective date, or 180 days after the final administrative decision on a category determination submission under 403.6(a)(4), whichever is later.
“baseline report. Within 180 days after the effective date of a categorical Pretreatment Standard, or 180 days after the final administrative decision made upon a category determination submission under § 403.6(a)(4), whichever is later, existing Industrial Users subject to such categorical Pretreatment Standards and currently discharging to or scheduled to discharge to a POTW shall be required to submit to the Control Authority a report”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
New Sources, and sources that become Industrial Users after a categorical Standard is promulgated, must submit their report to the Control Authority at least 90 days before discharge begins.
“At least 90 days prior to commencement of discharge, New Sources, and sources that become Industrial Users subsequent to the promulgation of an applicable categorical Standard, shall be required to submit to the Control Authority a report which contains the information listed in paragraphs (b)(1)-(5) of this section.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Categorical Industrial Users (except Non-Significant Categorical Users) must submit to the Control Authority, during June and December after the compliance date of the Standard (for a New Source, after its discharge begins), a report on the nature and concentration of the pollutants limited by the Standard, unless the Standard, the Control Authority or the Approval Authority requires more frequent reports. The report also includes measured or estimated average and maximum daily flows, and, where the Standard requires a Best Management Practice, the documentation the Control Authority or the Standard requires. The Control Authority may modify the months in which these reports are submitted, considering factors such as local high or low flow rates, holidays and budget cycles.
“Any Industrial User subject to a categorical Pretreatment Standard (except a Non-Significant Categorical User as defined in § 403.3(v)(2)), after the compliance date of such Pretreatment Standard, or, in the case of a New Source, after commencement of the discharge into the POTW, shall submit to the Control Authority during the months of June and December, unless required more frequently in the Pretreatment Standard or by the Control Authority or the Approval Authority, a report indicating the nature and concentration of pollutants in the effluent which are limited by such categorical Pretreatment Standards. In addition, this report shall include a record of measured or estimated average and maximum daily flows for the reporting period for the Discharge reported in paragraph (b)(4) of this section except that the Control Authority may require more detailed reporting of flows. In cases where the Pretreatment Standard requires compliance with a Best Management Practice (or pollution prevention alternative), the User shall submit documentation required by the Control Authority or the Pretreatment Standard necessary to determine the compliance status of the User. At the discretion of the Control Authority and in consideration of such factors as local high or low flow rates, holidays, budget cycles, etc., the Control Authority may modify the months during which the above reports are to be submitted.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
All categorical and non-categorical Industrial Users must notify the POTW immediately of all discharges that could cause problems to the POTW, including slug loadings.
“All categorical and non-categorical Industrial Users shall notify the POTW immediately of all discharges that could cause problems to the POTW, including any slug loadings, as defined by § 403.5(b), by the Industrial User.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
If an Industrial User's own sampling shows a violation, it must notify the Control Authority within 24 hours of becoming aware of it, then repeat the sampling and submit the results within 30 days after becoming aware of it (see the next point for when resampling is not required).
“If sampling performed by an Industrial User indicates a violation, the User shall notify the Control Authority within 24 hours of becoming aware of the violation. The User shall also repeat the sampling and analysis and submit the results of the repeat analysis to the Control Authority within 30 days after becoming aware of the violation.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Resampling is not required if the Control Authority samples at the Industrial User at least once per month, or if it samples at the User between the initial sampling and the time the User or the Control Authority receives the results (one of the options).
“Resampling is not required if: (i) The Control Authority performs sampling at the Industrial User at a frequency of at least once per month; or (ii) The Control Authority performs sampling at the User between the time when the initial sampling was conducted and the time when the User or the Control Authority receives the results of this sampling.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
For the reports under 403.12(b), (d), (e) and (h), grab samples must be used for pH, cyanide, total phenols, oil and grease, sulfide and volatile organic compounds. Other pollutants require 24-hour flow-proportional composite samples unless the Control Authority authorizes time-proportional composite or grab sampling.
“The reports required in paragraphs (b), (d), (e) and (h) of this section must be based upon data obtained through appropriate sampling and analysis performed during the period covered by the report, which data are representative of conditions occurring during the reporting period. The Control Authority shall require that frequency of monitoring necessary to assess and assure compliance by Industrial Users with applicable Pretreatment Standards and Requirements. 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 flow-proportional composite sampling techniques, unless time-proportional composite sampling or grab sampling is authorized by the Control Authority.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Significant Non-categorical Industrial Users must report to the Control Authority at least once every six months, on dates the Control Authority specifies.
“Significant Non-categorical Industrial Users must submit to the Control Authority at least once every six months (on dates specified by the Control Authority) a description of the nature, concentration, and flow of the pollutants required to be reported by the Control Authority.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
All Industrial Users must promptly notify the Control Authority (and the POTW, if it is not the Control Authority) in advance of any substantial change in the volume or character of pollutants in their Discharge.
“All Industrial Users shall promptly notify the Control Authority (and the POTW if the POTW is not the Control Authority) in advance of any substantial change in the volume or character of pollutants in their Discharge,”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Not covered here
The full contents of the baseline report, reduced reporting conditions in 403.12(e)(3), electronic reporting dates and the hazardous waste quantity rules in 403.12(p)(2) are not all repeated here; see the linked section. We only write what an official source states, so study these parts with your certifying program's materials.
Signatures, records and POTW reports
A POTW with an approved Pretreatment Program must submit a report on its program activities to the Approval Authority no later than one year after program approval and at least annually after that.
“POTWs with approved Pretreatment Programs shall provide the Approval Authority with a report that briefly describes the POTW's program activities, including activities of all participating agencies, if more than one jurisdiction is involved in the local program. The report required by this section shall be submitted no later than one year after approval of the POTW's Pretreatment Program, and at least annually thereafter,”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Reports under 403.12(b), (d) and (e) must include the 403.6(a)(2)(ii) certification statement and, for a corporation, be signed by a responsible corporate officer.
“The reports required by paragraphs (b), (d), and (e) of this section shall include the certification statement as set forth in § 403.6(a)(2)(ii), and shall be signed as follows: (1) By a responsible corporate officer, if the Industrial User submitting the reports required by paragraphs (b), (d), and (e) of this section is a corporation.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
POTW reports to the Approval Authority under 403.12(i) must be signed by a principal executive officer, ranking elected official or other duly authorized employee.
“Reports submitted to the Approval Authority by the POTW in accordance with paragraph (i) of this section must be signed by a principal executive officer, ranking elected official or other duly authorized employee.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Industrial Users and POTWs subject to the 403.12 reporting requirements must keep records of all information from monitoring required by that section, including Best Management Practices documentation; for all samples, the records include the date, exact place, method and time of sampling and the names of the person or persons taking the samples.
“Any Industrial User and POTW subject to the reporting requirements established in this section shall maintain records of all information resulting from any monitoring activities required by this section, including documentation associated with Best Management Practices. Such records shall include for all samples: (i) The date, exact place, method, and time of sampling and the names of the person or persons taking the samples;”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Industrial Users and POTWs subject to the reporting requirements must keep records of monitoring activities and results for at least 3 years and make them available to the Director and Regional Administrator (and the POTW, for an Industrial User); the period is extended during unresolved litigation or when the Director or Regional Administrator requests.
“Any Industrial User or POTW subject to the reporting requirements established in this section (including documentation associated with Best Management Practices) shall be required to retain for a minimum of 3 years any records of monitoring activities and results (whether or not such monitoring activities are required by this section) and shall make such records available for inspection and copying by the Director and the Regional Administrator (and POTW in the case of an Industrial User). This period of retention shall be extended during the course of any unresolved litigation regarding the Industrial User or POTW or when requested by the Director or the Regional Administrator.”
40 CFR 403.12, Reporting requirements for POTW's and industrial users
Upset and bypass
An Upset is an exceptional incident of unintentional and temporary noncompliance with categorical standards caused by factors beyond the Industrial User's reasonable control. It does not include noncompliance caused by operational error, poor design, inadequate facilities, lack of preventive maintenance or careless or improper operation.
“Upset means an exceptional incident in which there is unintentional and temporary noncompliance with categorical Pretreatment Standards because of factors beyond the reasonable control of the Industrial User. 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.”
To establish the affirmative defense of Upset, the Industrial User must show, through properly signed, contemporaneous operating logs or other relevant evidence, that an Upset occurred and it can identify the cause, that the facility was being operated in a prudent and workman-like manner and in compliance with applicable operation and maintenance procedures, and that it submitted the required information to the POTW and Control Authority within 24 hours of becoming aware of the Upset (with a written submission within five days if it was given orally).
“An Industrial User who wishes to establish the affirmative defense of Upset shall demonstrate, through properly signed, contemporaneous operating logs, or other relevant evidence that: (1) An Upset occurred and the Industrial User can identify the cause(s) of the Upset; (2) The facility was at the time being operated in a prudent and workman-like manner and in compliance with applicable operation and maintenance procedures; (3) The Industrial User has submitted the following information to the POTW and Control Authority within 24 hours of becoming aware of the Upset (if this information is provided orally, a written submission must be provided within five days):”
In any enforcement proceeding, the Industrial User seeking to establish that an Upset occurred has the burden of proof.
“In any enforcement proceeding the Industrial User seeking to establish the occurrence of an Upset shall have the burden of proof.”
On reduction, loss or failure of its treatment facility, the Industrial User must control production or all Discharges as needed to stay in compliance with categorical Pretreatment Standards until the facility is restored or alternative treatment is provided.
“The Industrial User shall control production or all Discharges to the extent necessary to maintain compliance with categorical Pretreatment Standards upon reduction, loss, or failure of its treatment facility until the facility is restored or an alternative method of treatment is provided.”
Bypass is the intentional diversion of wastestreams from any portion of an Industrial User's treatment facility.
“Bypass means the intentional diversion of wastestreams from any portion of an Industrial User's treatment facility.”
A bypass that does not cause Pretreatment Standards or Requirements to be violated may be allowed only if it is also for essential maintenance to assure efficient operation.
“An Industrial User may allow any bypass to occur which does not cause Pretreatment Standards or Requirements to be violated, but only if it also is for essential maintenance to assure efficient operation.”
If an Industrial User knows in advance of the need for a bypass, it must give prior notice to the Control Authority, if possible at least ten days before.
“If an Industrial User knows in advance of the need for a bypass, it shall submit prior notice to the Control Authority, if possible at least ten days before the date of the bypass.”
An unanticipated bypass that exceeds applicable Pretreatment Standards needs oral notice to the Control Authority within 24 hours and a written submission within 5 days; the Control Authority may waive the written report case by case if the oral report was received within 24 hours.
“An Industrial User shall submit oral notice of an unanticipated bypass that exceeds applicable Pretreatment Standards to the Control Authority within 24 hours from the time the Industrial User becomes aware of the bypass. A written submission shall also be provided within 5 days of the time the Industrial User becomes aware of the bypass. The written submission shall contain a description of the bypass and its cause; the duration of the bypass, including exact dates and times, and, if the bypass has not been corrected, the anticipated time it is expected to continue; and steps taken or planned to reduce, eliminate, and prevent reoccurrence of the bypass. The Control Authority may waive the written report on a case-by-case basis if the oral report has been received within 24 hours.”
Bypass is prohibited, and the Control Authority may take enforcement action for it, unless it was unavoidable to prevent loss of life, personal injury or severe property damage, there were no feasible alternatives, and the Industrial User submitted the required notices. The Control Authority may approve an anticipated bypass, after considering its adverse effects, if it determines the bypass will meet those three conditions.
“Bypass is prohibited, and the Control Authority may take enforcement action against an Industrial User for a bypass, unless; (i) Bypass was unavoidable to prevent loss of life, personal injury, or severe property damage; (ii) There were no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, or maintenance during normal periods of equipment downtime. This condition is not satisfied if adequate back-up equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment downtime or preventative maintenance; and (iii) The Industrial User submitted notices as required under paragraph (c) of this section. (2) The Control Authority may approve an anticipated bypass, after considering its adverse effects, if the Control Authority determines that it will meet the three conditions listed in paragraph (d)(1) of this section.”
Sources
- eCFR: 40 CFR 403.1, Purpose and applicability (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.3, Definitions (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.5, National pretreatment standards: Prohibited discharges (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.6, National pretreatment standards: Categorical standards (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.8, Pretreatment Program Requirements: Development and Implementation by POTW (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.12, Reporting requirements for POTW's and industrial users (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.16, Upset provision (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 403.17, Bypass (as of Nov 4, 2026)Checked November 6, 2026
Other Wastewater operator study guides: Secondary treatment standards, NPDES permit conditions, Permit limits and monitoring, Sampling and test procedures, Biosolids use and disposal, Pathogen and vector attraction reduction