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Effluent Guidelines

Centralized Waste Treatment Effluent Guidelines

EPA promulgated the Centralized Waste Treatment (CWT) Effluent Guidelines and Standards (40 CFR Part 437) in 2000 and amended the rule in 2003. The regulations cover discharges from facilities that treat or recover metal-bearing, oily, and organic wastes, wastewater, or used material received from off-site. The CWT Effluent Guidelines and Standards are incorporated into NPDES permits for direct dischargers, and permits or other control mechanisms for indirect dischargers (see Pretreatment Program).
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What is Centralized Waste Treatment?

The centralized waste treatment industry handles wastewater treatment residuals and industrial process by-products that come from other industries. CWT facilities receive a wide variety of hazardous and non-hazardous industrial wastes for treatment. Many of the wastes contain very high pollutant concentrations and are unusually difficult to treat.

CWT facilities typically fall within NAICS codes 562211 (hazardous waste treatment and disposal), 562219 (other nonhazardous waste treatment and disposal) and 562920 (materials recovery facilities).

Facilities Covered

The CWT Effluent Guidelines apply to facilities in four subcategories:
  1. Metals Treatment and Recovery
  2. Oils Treatment and Recovery
  3. Organics Treatment and Recovery
  4. Multiple Wastestreams
Examples of discharges covered by the regulation:
  • Discharges from stand-alone waste treatment and recovery facilities receiving materials from off site. These facilities may treat hazardous or non-hazardous waste, hazardous or non-hazardous wastewater, and/or used material from off site, for disposal, recycling or recovery.
  • Certain discharges from waste treatment systems at facilities primarily engaged in other industrial operations. Thus, industrial facilities which process their own, on-site generated, process wastewater with hazardous or non-hazardous wastes, wastewaters, and/or used material received from off site, in certain circumstances, may be subject to this category with respect to a portion of their discharge.

Covered wastestreams include materials received from off-site, solubilization water, used oil/emulsion breaking wastewater, tanker truck/drum/roll-off box washes, equipment washes, air pollution control waters, laboratory-derived wastewater, wastewater from on-site industrial waste combustors, landfills, and contaminated stormwater.

The CWT category does not apply to:
  • operations at facilities which are subject to other effluent guidelines categories and which receive wastes from off-site for treatment or recovery that are subject to the same effluent guidelines as the on-site generated wastes
  • operations at facilities which receive off-site wastes whose nature and treatment are compatible with the treatment of on-site non-CWT wastes
  • operations engaged exclusively in landfilling and/or the treatment of landfill wastewaters, whether generated on- or off-site (See also the Landfills Effluent Guidelines, 40 CFR Part 445)

Facilities that treat wastewater that results from cleaning tanker trucks, rail tank cars, or barges may be subject to the CWT effluent guidelines if not subject to the Transportation Equipment Cleaning Effluent Guidelines (40 CFR Part 442).

See the applicability and definitions sections in 40 CFR Part 437 for complete descriptions of coverage and exclusions.

Compliance Assistance

  • Small Entity Compliance Guide (2001)
    A plain language explanation of how to comply with the CWT regulation; with Frequently Asked Questions (2003 and 2006)

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Study of CWT and Oil & Gas Wastewater – 2018

EPA conducted a study of CWT facilities accepting oil and gas extraction wastewater from 2014 to 2017. EPA has prepared a compilation of data collected to date, including information on CWT facilities that accept such wastewater, available treatment technologies (and their associated costs), discharge characteristics, financial characteristics of CWT facilities and the environmental impacts of discharges from CWT facilities.
In 2018, EPA announced as part of its effluent guidelines planning process that it is beginning a holistic study of oil and gas extraction wastewater management under the Clean Water Act. As part of that study, EPA will continue to evaluate the role of CWT facilities in managing oil and gas extraction wastewater from onshore wells.

Rulemaking History

Additional Information

For additional information regarding the CWT Effluent Guidelines, please contact Jesse Pritts ( or 202-566-1038.

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