The NPDES program has improved water quality in the United States by requiring pollutant discharge permits from point sources to the waters of the United States. See the EPA official definition of a point source, (Links to an external site.)Links to an external site. but a point source can be an industry that discharges its waste to a stream or river, or it can be a municipality (a city, town, or other community) that collects wastewater from sewer systems into a publicly owned treatment work (POTW) facility, often called a wastewater treatment plant, that treats the wastewater and then the cleaned water to lakes, rivers, or streams. Both industries and POTWs that discharge directly to waters of the United States must obtain an NPDES permit prior to discharging any wastewater, and the permit likely will require treatment to remove contaminants harmful to humans or aquatic life. The wastewater treatment process at the POTW can involve a variety of processes, including separation of the solids through sedimentation or filtration, oil/water separation, microbial denitrification, and residual disinfection.

Unfortunately, many industrial processes that discharge to municipal sewer systems, including chrome plating and metal finishing, chemical manufacturers, machine shops, laboratories, industrial laundry and dry cleaning operations, and boiler operations, can result in wastewater that can harm or bypass the POTW treatment process.

EPA's National Pretreatment Program (Links to an external site.)Links to an external site. authorizes local municipalities that operate POTWs to perform permitting, administrative, and enforcement tasks for discharges from industries that will flow into the into the municipalities’ POTW. For example, the city of Tulsa has an industrial pretreatment program. (Links to an external site.)Links to an external site. This program is intended to prevent pollutants into the sanitary sewer that could:

• hinder the ability of the wastewater treatment facilities to operate effectively,
• pass through the wastewater treatment facility to the receiving river or stream,
• inhibit the city's ability to economically dispose of wastewater residuals (biosolids),
• result in concerns about worker health and safety,
• damage the sanitary sewer system,
• cause an obstruction in the sanitary sewer.

As a result, the city requires that users meet discharge standards and obtain a permit to discharge into the sanitary sewer system.

Perform research on the industrial pretreatment requirements in your city, or a city of your choice, that would impact an industrial facility wishing to operate there. Identify:

• The city, town, or other municipality.
• A summary of the permitting requirements and the types of facilities that may need to comply.
• A description of some of the chemical and biological limitations, i.e., is there a limitation on Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), pH, oil and grease, metals, etc. in the discharge? Are there temperature or color limitations? What other limitations are identified?
• Is sampling of the discharge required as a condition of or to apply for the permit? If so, describe the sampling required and the frequency.
• Does the municipality provide a wastewater discharge permit application online? If so, provide a link and summarize some of the requirements and information that has to be compiled to complete and submit the permit application.
• Is pretreatment specified for certain operations? For example, are grease traps specified, must acids be neutralized, are other control measures indicated?

If you cannot find the information online for your particular city/municipality, find a city that does provide this information online. For example, the City of Springfield, Massachusetts (Links to an external site.)Links to an external site. has a good discussion, with permitting requirements. The City of South Daytona, Florida (Links to an external site.)Links to an external site. publishes the regulations for its city discharge requirements. Plenty of cities/municipalities do provide this information freely, so if you don't find it right away, you may need to call your local facility to ask where the information is found, or find a city that does provide it, such as Springfield or South Daytona.