Frequently Asked Questions

Pretreatment involves treating industrial process wastewater to reduce, alter, or eliminate pollutants prior to discharge into the sanitary sewer system and ultimately a wastewater treatment plant. This can be achieved by a physical process (e.g. filtration, dissolved air flotation, or sedimentation), chemical process (e.g. chemical substitutions, precipitation, or neutralization), or biological process (e.g. aerobic digestion).  

North Texas Municipal Water District (NTMWD) provides wholesale wastewater services to 24 communities and more than 1.5 million residents in our North Texas service area. Wastewater enters the various municipal sewer collection systems before entering our NTMWD wastewater conveyance system. The NTMWD wastewater conveyance system consists of more than 237 miles of large-diameter pipelines, 23 lift stations, and 13 wastewater treatment plants (WWTPs), also known as publicly-owned treatment works or POTWs. These facilities convey and treat approximately 163 million gallons of wastewater daily. Once through the advanced WWTP treatment process, the cleaned water meets or surpasses all regulatory requirements and is released back into our waterways to blend with larger water supply sources in the State.

The NTMWD Industrial Pretreatment Program is mandated by the Federal Water Pollution Control Act, commonly referred to as the Clean Water Act, to prevent the introduction of pollutants into a wastewater treatment plant that will interfere with its operation by inhibiting or disrupting the treatment processes or that will pass through the treatment plant into waters of the United States, thus negatively impacting water quality. It was also established to help protect the health and safety of the public, environment, and wastewater system workers. Federal regulations governing the pretreatment program can be found in 40 CFR Part 403. The NTMWD Pretreatment team, in partnership with city counterparts, manages eight TCEQ-approved pretreatment programs covering nine wastewater treatment plants and more than 20 cities, including our contract with the City of Terrell to manage its pretreatment program. 

Specific prohibitions are found in each city’s sewer use ordinance. The following pollutants shall not be introduced into a wastewater treatment plant:

• Pollutants that cause pass through or treatment inhibition;
• Pollutants which create a fire or explosion hazard in the POTW;
• Pollutants which will cause corrosive structural damage to the POTW, but in no case discharges with pH lower than 5.0;
• Solid or viscous pollutants, such as oil and grease, in amounts which will cause obstruction to flow in the POTW resulting in interference;
• Any pollutant, including oxygen demanding pollutants such as BOD or COD released in a discharge at a flow rate and/or pollutant concentration which will cause interference with the POTW (also known as high-strength wastes);
• Excessive heat in amounts which will inhibit biological activity in the POTW resulting in interference;
• Petroleum oil, nonbiodegradable cutting oil, or products of mineral oil origin in amounts that will cause interference or pass through;
• Pollutants which result in the presence of toxic gases, vapors, or fumes within the POTW in a quantity that may cause acute worker health and safety problems; and,
• Any trucked or hauled pollutants, except at discharge points designated by the POTW.

All non-domestic users that discharge to the municipal sewer system must comply with the sewer use ordinance of the city where the industrial facility is located, however, only Significant Industrial Users (SIUs) are required to obtain an Industrial User permit.

Significant Industrial Users are:

• All Industrial Users subject to categorical industrial user requirements under 40 CFR 403.6 and 40 CFR Chapter I, Subchapter N, even if they do not discharge categorical process wastewater; or,
• Any other Industrial User that: 
  • discharges an average of 25,000 gallons per day or more of process wastewater to the POTW (excluding sanitary, noncontact cooling, and boiler blowdown wastewater);
  • contributes a process wastestream which makes up 5 percent or more of the average dry weather hydraulic or organic capacity of the POTW Treatment plant; or,
• Is designated as such by the City or NTMWD given the Industrial User has reasonable potential for adversely affecting the POTW's operation or for violating any Pretreatment Standard or requirement in accordance with 40 CFR 403.8(f)(6).

A permit application should be submitted if:

• You are a Significant Industrial User based on the definition above; or,
• You discharge high-strength wastewater containing biochemical oxygen demand (BOD), ammonia, etc. 

You may also contact our Pretreatment team at pretreatment.info@ntmwd.com prior to completing the application to discuss further.  See pretreatment requirements for additional information.

No. Sometimes, the only way to determine if your business will require an Industrial User permit is to review all information requested in the permit application.

Local limits represent the maximum discharge quantity allowed for each pollutant.  Some of our WWTPs have the ability to transfer flows to other WWTPs, and therefore the more stringent WWTP limit is applied in the industrial user permit. Some categorical industrial users may have additional or stricter limits as developed by the U.S. Environmental Protection Agency.

The NTMWD builds close working relationships with cities and industries by encouraging frequent communication to achieve mutually beneficial economic and environmental goals; however, industries that violate requirements of the federal regulations or industrial user permit will be subject to enforcement action. The NTMWD follows an enforcement response plan with escalating levels of enforcement based on the severity of noncompliance. The enforcement response plan helps to ensure consistent enforcement for similar violations. Enforcement actions can range from a phone call to monetary fines to sewer or water service termination.