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 The City of Carrollton’s Industrial Pretreatment Program (IPP) permits, inspects, and collects samples to ensure compliance with federal prohibited discharge standards and specific pollutant limitations outlined in 40 CFR Part 403. Significant Industrial Users (SIUs) are required to obtain a wastewater discharge permit prior to discharging any process wastes into the sanitary sewer. A facility is determined to be an SIU if: 

  • it is subject to categorical pretreatment standards,  

  • discharges 25,000 gallons per day or more of process wastewater,  

  • contributes a large organic loading, or  

  • has a reasonable potential for adversely affecting the collection system or treatment plant. 

These facilities are identified through Certificate of Occupancy applications, Environmental Surveys, and facility inspections. Once they are identified as needing to be included in our Industrial Pretreatment Program, industries are required to complete an application linked here.

Once the permit application is reviewed, the permit is then written and wastewater discharge limits are set based on local limits, type of discharge, quantity of discharge, and/or production volume. 

 After the permit has taken effect, industries are required to complete annual facility and records inspections, regular sampling events, and semi-annual and/or quarterly reporting.

 If you are an industry that believes that you may be subject to the Industrial Pretreatment Program or if you have any questions related to the permitting process, please reach out to us at

 ipp diagram

This image displays the harmful effects that our Industrial Pretreatment Program aims to prevent by regularly inspecting users and permitting those who could potentially negatively impact our sewers and wastewater treatment plants.