Pretreatment Program

Industrial Pretreatment Program 


The Industrial Pretreatment Program provides monitoring, permitting and reporting of industrial and commercial wastewater discharges into the City of Flagstaff sewer system to assure compliance with Local, State and Federal mandated pretreatment regulations and to prevent pass through at the City’s water reclamation plants. Industrial byproducts can interfere with water reclamation operators or pass through the system untreated, potentially contaminating the Rio de Flag. The City’s Pretreatment program helps to reduce the amount of pollutants that are discharged into the City’s collection and treatment facilities.

Industrial User

Wastewater discharges from industrial and commercial operations are regulated through an industrial discharge permit system. A discharge permit is required for significant industrial users (SIUs) that are defined as any industry:

  • Is subject to categorical standards as defined by EPA 40 CFR 403.6 and 40 CFR Chapter 1, Subchapter N.
  • Discharges an average process waste stream of 25,000 gallons per day or more to the collection system
  • Contributes a process waste stream which makes up 5% or more of the average dry weather hydraulic or organic capacity of the treatment plant.
  • Has a reasonable potential, in the opinion of the Water Service’s Director, to adversely affect the City’s collection and treatment facilities.
For information on the program, please contact the Industrial Pretreatment Supervisor at (928) 213-2117, or the Industrial Pretreatment Inspector at (928) 213-2119, or Industrial Pretreatment Inspector at (928) 213-2118.


FOG Program 

FOG stands for fats, oils, and grease. FOG can buildup and clog sewer and drainage pipes unless properly pretreated. Restaurants and food service facilities generate greasy water through cleaning and washing dishes. Approved grease interceptors are installed in all food producing facilities to capture FOG before it discharges to the public sewer. For interceptors to be effective, proper pump out service and regular inspections must be completed. Industrial Pretreatment monitors food service establishments to ensure they are effectively managing FOG.


Links and Resources


Industrial Waste Documents