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Contact Region 9

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Pretreatment Program

Note: EPA no longer updates this information, but it may be useful as a reference or resource. Latest information is available at EPA's National Pretreatment Program site.

Pretreatment Quick Finder
NPDES Home Pretreatment Home Compliance & Enforcement Discharger Information Awards Local Limits Program Implementation Contacts

People use water in their homes for drinking, washing dishes, laundry, bathing, and toilet flushing. The resulting dirty water usually drains from homes into an extensive system of underground pipes that lead to a large municipal wastewater treatment plant. The treatment plant is designed to clean such domestic wastewater. The treated water is frequently released to a river, lake, or ocean.

Municipal treatment facility
Municipal treatment facility

Industry and businesses use water in many ways to manufacture products and provide services. For example, companies often use water to clean metal parts before they are painted. Companies frequently discharge the resulting dirty water into the same pipes to a municipal wastewater treatment plant. This non-domestic wastewater is often different than wastewater from homes, and may not be adequately treated at a municipal wastewater treatment plant. The word pretreatment refers to the treatment of non-domestic wastewater before it's discharged to a municipal wastewater treatment plant.

Industrial treatment facility
Industrial treatment facility

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The program controls a complex array of non-domestic wastewater through discharge standards and pollution prevention measures. The non-domestic dischargers in EPA’s Pacific Southwest Region include high-technology firms in the electronics and aerospace sectors, as well as significant food processing operations. The program is primarily implemented by local municipal pretreatment programs with assistance and oversight by the states and U.S. EPA.

The Pretreatment Program has dramatically reduced or eliminated discharges of non-domestic pollutants to municipal wastewater treatment plants and the nation's waters. In addition, the program has reduced the pollutants in municipal sewage sludge and allowed this material to be productively used as a soil amendment.

Pretreatment Program brochure (PDF) (4 pp, 250K)

Programs & Resources

Compliance & Enforcement

  • Discharger
  • Municipal


  • Discharger
  • Municipal


  • Local & State
  • Federal

Discharger Information

  • Application of Standards
  • Performance Benchmarks

Local Limits

  • Development
  • Implementation

Program Implementation

  • Program Performance
  • Guidance

Contact Information
Pretreatment contacts

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