Navigating the ever-changing PFAS water regulations

Navigating the ever-changing landscape of PFAS water regulations is no easy task. Over the last year, the U.S. Environmental Protection Agency (EPA) has been busy finalizing regulations and guidance on maximum contaminant levels (MCLs), water quality-based criteria, technology-based effluent limits, and more. However, recent changes in the federal administration have paused several PFAS-related regulations. Here, we examine the PFAS water regulations that are in effect, paused, and in development.

Regulations and guidelines currently in effect

Maximum contaminant levels (MCLs)

The EPA finalized the National Primary Drinking Water Regulation (NPDWR) under the Safe Drinking Water Act for six per- and polyfluoroalkyl substances (PFAS) in April 2024, after considering over 120,000 comments. These MCLs (see table below) are enforceable and supersede state-specific drinking water limits. Under this regulation, by 2027, all public water systems must be monitored for PFAS, and the levels of PFAS in drinking water must be shared with the public. If monitoring data exceeds MCLs, PFAS levels must then be reduced by 2029.

By 2027, all public water systems must be monitored for PFAS, and the levels of PFAS in drinking water must be shared with the public. If monitoring data exceeds MCLs, PFAS levels must then be reduced by 2029.

On February 7, 2025, in American Water Works Association, et al., v. EPA, a 60-day stay was issued on the regulation to allow the new federal administration time to review. Two months later, the U.S. Court of Appeals extended the stay by 30 days. The EPA now has until May 12 to file any additional motions. When this regulation was initially proposed in 2023, Barr dove into its potential implications. Now, as we inch closer to the regulation’s deadlines, we evaluate the latest information about its impact on future NPDES permits.

Under the Clean Water Act (CWA), states use water quality criteria to derive effluent limits for National Pollutant Discharge Elimination System (NPDES) permits that regulate point-source discharges to waterbodies. When developing effluent limits for an NPDES permit, note that discharge limits must support the uses of the receiving waterbody. For example, if the receiving waterbody is a drinking water source, MCLs may influence the development of human health-based water quality criteria and related permit effluent limits.

In some states, MCLs are automatically incorporated into the state’s water quality criteria by rule and may be applied to the derivation of effluent limits. Other states may use their own regulatory process to develop and adopt water quality criteria that takes federal MCLs into consideration.

Timeline

• April 26, 2024: Published in Federal Register
• June 25, 2024: Effective date of rule
• February 7, 2025: 60-day stay issued
• April 10, 2025: Additional 30-day stay issued
• May 12, 2025: EPA’s deadline to file any additional motions
• April 26, 2027: All drinking water systems must have completed initial monitoring, consumer confidence reports, and public notifications of monitoring and testing violations
• April 26, 2029: All drinking water systems must comply with the MCLs and notify the public of MCL violations

PFAS maximum contaminant levels finalized in April 2024

Aquatic life-based criteria and benchmarks

In September 2024, the EPA released guidelines to protect aquatic life from 10 different PFAS chemicals (see table below). The water quality criteria and benchmarks are not regulatory limits, but states, territories, and tribes can use them to set local water quality criteria. These criteria inform the development of water quality-based effluent limits in discharge permits. The numeric criteria specifically cover long-term exposure to PFOA and PFOS in freshwater, while the benchmarks cover short-term exposure to eight other PFAS in freshwater as well as PFOA and PFOS in saltwater.

Aquatic life-based criteria and benchmarks finalized in September 2024

Technology-based effluent limits

In January 2025, the EPA issued a how-to guide for permit writers on implementing case-by-case technology-based effluent limitations in NPDES permits for pollutants of emerging concern, including PFAS. The guidance references several EPA reports that permit writers can use to identify PFAS treatment technologies for developing best available technology (BAT) permit limits.

PFAS regulations under the new administration

On January 20, 2025, an executive order was issued prohibiting the EPA from proposing or issuing new rules until a new appointee or designee reviews and approves them. This order also requires agencies to consider postponing the effective date of already issued rules to allow new government staff the opportunity to review them. In January 2025, the EPA withdrew its draft proposal to add PFAS to the chemical manufacturing sector’s Effluent Limitations Guidelines (ELG). ELG revisions for other sectors may also be impacted.

Other hot topics

Many regulatory developments are currently underway and/or out for public comment. Barr will continue to monitor these developments in the coming months.

• Draft health-based criteria: In December 2024, the EPA published draft recommendations for health-based water quality criteria for three PFAS: PFOA, PFOS, and PFBS. Once finalized, these criteria can help states, territories, and tribes set water quality-based criteria and standards to protect human health from PFAS exposure through water, fish, and shellfish. The public comment period ended earlier this month.

• Draft Minnesota Industrial Stormwater general permit: In January 2025, the Minnesota Pollution Control Agency released the draft 2025 Minnesota Industrial Stormwater general permit, which will go into effect in May. The draft requires businesses with specific standard industrial classification (SIC) codes to conduct PFAS sampling. Some facilities outside of these SIC codes are also receiving permit-specific monitoring requirements. This applies to facilities with permit coverage and those that want to certify no exposure. The public comment period ended in February 2025.

• Biosolids: In January 2025, the EPA released a draft risk assessment to advance scientific understanding of PFOA and PFOS in biosolids. The draft risk assessment findings show that there may be human health risks associated with exposure to PFOA or PFOS through the use or disposal of biosolids via land application, surface disposal in landfills, or incineration. The public comment period ended in March 2025.

• Draft Multi-Sector General Permit: In December 2024, the EPA released the draft 2026 NPDES Multi-Sector General Permit (MSGP) for stormwater discharges from industrial activities, which includes PFAS monitoring. Once finalized, this permit will replace the 2021 MSGP and applies to industrial facilities in areas where the EPA is the NPDES permitting authority. The public comment period is open through May 19, 2025. This permit issuance may be delayed depending on federal policies.

• Monitoring: Many of the new requirements being implemented involve monitoring PFAS in waste streams. The requirements, including the type of PFAS monitored, frequency, benchmarks, thresholds, and follow-up actions, vary by state. To ensure compliance, review the guidelines for your state.

• Effluent limit guidelines: The EPA intends to continue limiting PFAS discharges from industrial categories through the Preliminary Effluent Guidelines Program Plan 16. The agency is conducting detailed studies to make informed, data-driven decisions about whether new rulemaking is needed to establish revised effluent limitations guidelines.

• Local permits: Incorporation of PFAS MCLs into individual or site-specific permits is beginning to take place. As permits are issued in each state or region, it will be important to track how new PFAS criteria and limits are incorporated.

How can we help?

The implementation of PFAS MCLs in discharge permits is evolving and requires collaboration among those involved as individual states incorporate federal guidance differently. Barr has experience navigating various state implementations and has been assisting both public and industrial facilities across the U.S. with issues related to PFAS in their permits. For over two decades, we have conducted sampling and analysis aimed at source reduction and have assisted with water treatment design for PFAS. Contact us to learn more about what’s happening in your state, our PFAS work, and how Barr can assist you.

About the authors

Andrea Collier, vice president and senior environmental engineer, has 22 years of experience in water resources management; stormwater and wastewater infrastructure design and NPDES permitting; process control; and waste management. Her background in PFAS-related projects includes permitting, environmental audits, sample collection, data analysis, and stormwater infrastructure and treatment.

Kristine Corneillie, senior environmental engineer, has 25 years of experience consulting on water quality, wastewater, stormwater, recycled water, and watershed management projects. She has assisted clients with NPDES permit renewal applications and negotiations, special studies, and enforcement proceedings. Her background includes drafting regional watershed permits and plans, TMDL implementation, industrial wastewater compliance, trash reduction and implementation, and sampling and analysis plans.

Related projects

Wastewater antidegradation analysis and NPDES permit renewal

Barr conducted a wastewater antidegradation analysis for a large chemical producer that was anticipating increased organic pesticide production. We evaluated the following parameters against water quality standards: total suspended solids, chemical oxygen demand, biochemical oxygen demand, total organic pesticides, and the organic pesticide subject to the planned production increase. The analysis found that the planned production increase would be minimally degrading to the receiving water body. Barr then prepared the NPDES permit renewal application, including a mixing-zone study, a parameter table for each outfall, and a background-information document to help state regulators understand the complexities of the facility in relation to its wastewater discharge.

Environmental services at manufacturing facility

Since 2006, Barr has provided a wide range of environmental services to a confidential manufacturing client in the Upper Midwest, including developing a long-term remediation plan for historical contamination. Barr has tackled unique site challenges, including contamination in fine-grained soils beneath the active facility, and evaluated innovative remedial solutions. The project includes groundwater monitoring, reporting, and modeling; geotechnical work; PFAS evaluations; NPDES permitting assistance; and water treatment system upgrades.

PFAS-impacted drinking water response and treatment plant design

Barr assisted the City of Bemidji, Minnesota, in addressing PFAS contamination from aqueous-film-forming foam (AFFF) used at the city’s airport, which had migrated into the city’s groundwater and drinking-water-supply wells. Barr developed well-pumping modifications and groundwater modeling to predict how quickly the water quality would change due to the modified pumping scheme. We then implemented near-term actions while long-term solutions were evaluated. Barr facilitated tests to determine the most effective PFAS treatment technology and designed a 2.2 million-gallons-per-day drinking water treatment plant with greensand filtration for iron and manganese removal, followed by granular activated carbon (GAC) treatment for PFAS removal. We also helped secure over $20 million in bonding and related funding for the project. Barr provided full-time construction observation and administration services leading up to the plant’s start-up. The new treatment plant has provided Bemidji with water free of PFAS, iron, and manganese since early 2021.

Multi-site PFAS remedial investigation and remediation

When PFAS was detected in public water supplies and private wells at or near active and former manufacturing facilities owned by Saint-Gobain Performance Plastics, Barr conducted remedial investigations and feasibility studies as part of a collaborative consulting team. The team evaluated potential release mechanisms from multiple facilities, including sampling and analyzing process streams, air emissions, and process wastewater. Barr is leading development and iterative refinement of complex site conceptual models that incorporate coupled air-dispersion, groundwater-flow, and fate-and-transport models. We conducted PFAS water-treatment bench- and pilot-testing, evaluated treatment-technology options such as granular activated carbon and ion exchange, and designed a full-scale pretreatment system.