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Pretreatment Program

What is Pretreatment?

Pretreatment refers to the act of treating wastewater to remove any harmful pollutants before it enters the Publicly Owned Treatment Works. Since a typical wastewater treatment plant is only capable of treating domestic wastewater, the introduction of toxic pollutants from industrial processes can cause problems at the plant and have detrimental effects on the plant’s effluent water quality. Through a permitting and monitoring process, the amount of industrial pollutants entering the POTW is greatly reduced.

In Scottsdale, the Pretreatment Program is part of Water Resources Water Quality Department and is mandated by the EPA. 


 Industrial Pretreatment Includes
- Metal Plating
- Circuit Board Manufacturing

 Fats, Oils and Grease (FOG)
- In Restaurants
- In Your home

 Petroleum Oil and Grease (POG) Includes
- Car Washes
- Automotive Service and Repair

Benefits of Pretreatment Programs

  • Prevents the introduction of harmful pollutants from industrial and other non-domestic sources to the city’s sewer system that have the potential to damage the wastewater collections system 
  • Protects the function and operation of the city’s wastewater treatment plants 
  • Protects future use and disposal of wastewater biosolids 
  • Ensures public health and safety of Scottsdale residents, visitors and employees 
  • Promotes the reuse and recycling of reclaimed wastewater 
  • Complies with the National Pollutant Discharge Elimination System mandated by the EPA

History of Pretreatment

After establishing the Environmental Protection Agency in 1970, Congress passed the “Federal Water Pollution Control Act” to restore and maintain the quality of our nation’s water in 1972. It was amended in 1977 and retitled the “Clean Water Act” and includes requirements for industries and municipalities to control their discharges into designated waters of the United States.

The following year, the “General Pretreatment Programs Regulations” were established to enforce environmental protection standards for industries discharging pollutants into local sewer systems.

In 1979, Scottsdale entered into an agreement with Glendale, Mesa, Tempe and Phoenix to create the Sub-Regional Operating Group (SROG) to co-own and operate a joint wastewater collection and treatment facility. This facility, along with Scottsdale’s Water Reclamation and Gainey Ranch Reclamation plants were required to develop pretreatment programs to meet the EPA mandates and regulations.