Wastewater

Overview
   Relevant Activities
   Role of Local Governments
U.S. EPA Resources
Other Resources 
   States
   Other Federal Agencies & Programs
   Associations for Local Officials
Funding & Financing

Overview

WastewaterLocal governments are responsible for designing, planning, constructing, financing, operating, and maintaining wastewater treatment facilities and their conveyance systems, known as publicly owned treatment works (POTWs), in compliance with Clean Water Act (CWA) regulations. POTWs collect wastewater from homes, commercial buildings, and industrial facilities and transport it via a series of pipes (the "collection system") to the treatment plant. There, the POTW removes harmful organisms and other contaminants from the sewage, so it can be discharged safely into the receiving waters.

Generally, POTWs are designed to treat domestic sewage only, but they also receive wastewater from industrial users. EPA's General Pretreatment Regulations establish the responsibilities of federal, state and local governments; industry; and the public to implement Pretreatment Standards. The Standards aim to control pollutants originating with industrial users that may pass through or interfere with POTW treatment processes or that may contaminate sewage sludge.

Most collection systems constructed since the 1950s use dedicated sanitary sewers. However, these sometimes suffer from infiltration and inflow (I/I) of stormwater or groundwater, often during wet weather events. Large volumes of I/I can cause sanitary sewer overflows and operational problems at the wastewater treatment facility serving the collection system. Sewage overflows can be caused byother problems such as blockages, equipment failures, broken pipes, or vandalism. Collection systems that were designed to carry stormwater as well as sewage (combined systems) can also raise compliance issues when, during and after wet weather events, they exceed the conveyance and treatment capacity of the POTW and result in untreated discharges (combined sewer overflows, or 'CSOs').

Other wastewater collection and treatment activities that have compliance obligations include laboratory operations, biosolids management and disposal, chemical storage/hazardous materials management, and vehicle/equipment management.

The EPA oversees implementation of CWA wastewater programs and may take direct enforcement action even in states and Tribes that have received approval to operate these permit programs. Enforcement actions have been brought against cities and municipal POTWs, resulting in consent decrees (agreements filed with federal courts) which provide for the municipal entities to correct violations and invest funds.

EPA's Office of Wastewater Management (OWM) oversees programs protecting the nation's waters and watersheds. Its mission focuses on control of water and wastewater that is collected in discrete conveyances (also called point sources), including pipes, ditches, and sanitary or storm sewers. OWM is also home to the Clean Water State Revolving Fund and the Water Infrastructure Finance and Innovation Act (WIFIA) program, both of which offer various financial mechanisms to support water and wastewater infrastructure projects. Please see the Finance and Funding tab for more information.

Relevant Activities

Role of Local Governments

CWA NPDES Program

EPA administers the CWA programs with which local governments must comply. Under the CWA, a permit is needed to discharge a pollutant from a point source, such as a POTW, into the waters of the United States. CWA implementation is primarily carried out by states and several Tribes under delegated authority. EPA retains direct regulatory authority in a few states, all U.S. territories, and much of Indian Country. Implementation includes issuing NPDES permits to owners/operators of POTWs.

Permittees must comply with their designated discharge limitations and submit discharge monitoring reports (DMRs) showing their compliance with permit conditions. EPA establishes primary and secondary treatment standards, which are minimum, technology-based requirements for municipal wastewater treatment plants.

Permittees must also prevent unauthorized discharges such as sanitary sewer overflows (SSOs) and CSOs. This includes implementation of control strategies and, in the case of CSOs, long-term control plans.

Sanitary Sewer Overflows

SSOs that reach waters of the U.S. are considered point source discharges. This means SSOs are prohibited unless authorized by a NPDES permit.  Under the Supreme Court's decision in County of Maui v. Hawaii Wildlife Fund ('Maui decision'), SSOs that are discharged to groundwater and conveyed to waters of the U.S. may also constitute violations (EPA's Office of Water in September 2021 rescinded its earlier guidance document).  Moreover, SSOs, including those that do not reach waters of the U.S., may indicate that sewer systems are being improperly operated or maintained and may violate NPDES permit conditions. The Court in City and County of San Francisco v. EPA (2025) limited the types of requirements that can be included in a CWA discharge permit, ruling that "end result" requirements, which purport to make the permittee responsible for the quality of the water that receives its discharge, as distinct from other permit provisions regulating the quality of the water that is being discharged, were inconsistent with the statutory scheme and its history, and thus impermissible. SSOs can be prevented or controlled by following facility and operational best practices, including:

  • Sewer system cleaning and maintenance;
  • Reducing infiltration and inflow through system rehabilitation and repairing broken or leaking service lines;
  • Enlarging or upgrading sewer, pump station or sewage treatment plant capacity and/or reliability;
  • Limiting fats, oils, and grease into the sewer systems;
  • Construction of wet weather storage facilities;
  • Expanding the capacity of the treatment works; and
  • Public education.

Combined Sewer Overflows

CSOs convey untreated or partially treated human and industrial waste, toxic materials, and stormwater. EPA has prescribed nine minimum controls for operators of CSSs to implement. Permittees must prepare and implement a long-term control plan to eliminate the CSO and meet water quality standards. The nine minimum controls are:

  1. Proper operation and regular maintenance programs for the sewer system and CSO outfalls;
  2. Maximum use of the collection system for storage;
  3. Review and modification of pretreatment requirements to ensure that CSO impacts are minimized;
  4. Maximization of flow to the POTW for treatment;
  5. Elimination of CSOs during dry weather;
  6. Control of solid and floatable materials in CSOs;
  7. Pollution prevention programs to reduce contaminants in CSOs;
  8. Public notification to ensure that the public receives adequate notification of CSO occurrences and CSO impacts; and
  9. Monitoring to effectively characterize CSO impacts and the efficacy of CSO controls.

Biosolids Program

CWA regulations apply to management of biosolids, a byproduct of wastewater treatment. Section 405(d) of the CWA requires EPA to establish numeric limits and management practices that protect public health and the environment from the reasonably anticipated adverse effects of chemical and microbial pollutants during the use or disposal of sewage sludge. EPA also reviews biosolids regulations every two years to identify any additional pollutants that may occur and establishes regulations for those pollutants that prove harmful to human health or the environment.

Cybersecurity

For more information on cybersecurity, visit LGEAN's Cybersecurity page.

U.S. Environmental Protection Agency Resources

Other Resources

States

Other Federal Agencies & Programs

  • Industrial Assessment Centers. IAC engineering students provide no-cost assessments to manufacturers and water/wastewater treatment facilities, analyzing energy bills and energy and water systems including pumps, motors, compressed air, lighting, process heat, steam, and CHP, and the IACs then follow up with written energy-saving and productivity improvement recommendations, with estimates of related costs and payback periods.

Associations for Local Officials

Funding & Financing

For more information on Funding & Financing, please see the Wastewater and Stormwater section of LGEAN's Funding & Financing page. 

 

Back to Top