The national pretreatment program requires nondomestic dischargers that introduce pollutants to Publicly Owned Treatment Works (POTWs) to comply with pretreatment standards to ensure the goals of the Clean Water Act (CWA) are attained. The program also outlines requirements for POTWs to proactively protect its infrastructure while overseeing its management responsibilities.

The objectives of the program are to:

• prevent the introduction of pollutants into a POTW that will interfere with its operation, including interferenceinterferenceA discharge that, alone or in conjunction with a discharge or discharges from other sources, both (1) inhibits or disrupts the POTW, its treatment processes or operations, or its sludge processes, use, or disposal; and (2) therefore is a cause of a violation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation) or of the prevention of sewage sludge use or disposal in compliance with ... [applicable] statutory provisions and regulations or permits issued thereunder (or more stringent state or local regulations). [paraphrased from 40 CFR 403.3(k)] with its use or disposal of municipal sludge,
• prevent the introduction of pollutants into a POTW that will pass throughpass throughA discharge that exits the POTW into waters of the United States in quantities or concentrations that, alone or in conjunction with a discharge or discharges from other sources, is a cause of a violation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation). [40 CFR 403.3(p)] the treatment works or otherwise be incompatible with it, and
• improve opportunities to recycle and reclaim municipal and industrial wastewaters and sludges.

The national pretreatment program identifies specific discharge standards and requirements that apply to sources of nondomestic wastewater discharged to a POTW. By reducing or eliminating waste at the industries (“source reduction”), fewer toxic pollutants are discharged to and treated by the POTWs, providing benefits to both the POTWs and the industrial users.

• general and specific prohibitions,
• categorical pretreatment standards, and
• local limits.