On February 12, 2026, the U.S. Environmental Protection Agency (EPA) released a major update to its national drinking water monitoring data under the Fifth Unregulated Contaminant Monitoring Rule (UCMR 5). This dataset, representing nearly 95% of the monitoring results collected through 2025, gives the most comprehensive snapshot yet of the prevalence of per- and polyfluoroalkyl substances (PFAS) in America’s public water systems.
What Is UCMR 5 and Why It Matters
Every five years, under the Safe Drinking Water Act, the EPA requires select Public Water Systems (PWS) to monitor for contaminants not yet regulated under federal law. These data help the agency and the public understand which substances are present in drinking water and at what levels, informing future regulatory decisions.
UCMR 5 is noteworthy because it focuses on 29 PFAS compounds, all of which have limited nationwide occurrence data, but which have garnered significant public attention over the concerns they present to human health and the environment.
It’s important to note that unlike regulatory standards (such as legally enforceable maximum contaminant levels, or MCLs), UCMR monitoring does not determine compliance — it simply shows where and how often these contaminants occur.
Key Findings: PFAS “Forever Chemicals” Detected in Hundreds of Water Supplies
PFAS — a group of thousands of synthetic chemicals used in industry, firefighting foams, consumer products, and more — were a central focus of UCMR 5:
- A majority of the monitored PFAS were detected at least once at or above the minimum reporting levels (MRLs), showing that many of these chemicals are present in U.S. drinking water to some degree.
- Annual averages derived from the sample data show that a portion of sampling locations have PFAS levels that, when compared to current regulatory MCLs established in 2024, exceed those limits. According to Analysis by USA Today, this represents 1,050 water systems that provide drinking water to at least 52 million people, or more than 1 in 7 Americans.
- The highest presence was in large PWS serving over 10,000 people. To date, 12.0%, 10.9%, 0.05%, 1.0%, and 0.07% of large PWS had an average that was greater than the individual MCLs for PFOS, PFOA, HFPO-DA, PFHxS, and PFNA, respectively.
These findings align with concern in environmental research that PFAS contamination is widespread and persistent.
What the Data Mean for Public Health and Policy
The EPA and other stakeholders will use the UCMR 5 data to evaluate whether certain contaminants should be regulated. The prevalence of PFAS in the results are likely to draw the public’s attention and strongly support the ongoing implementation of PFAS drinking water standards adopted in 2024, even though the UCMR results themselves don’t establish legal compliance.
While much public attention has been focused on the Trump Administration’s de-regulatory efforts, PFAS appears to be one issue that continues to garner broad support from the public and the Trump Administration. EPA Administrator Lee Zeldin has said, “I have long been concerned about PFAS and the efforts to help states and communities dealing with legacy contamination in their backyards.” In order to treat drinking water to comply with the PFAS MCL, water systems will require expensive upgrades, and municipalities will likely resist paying the full bill, instead seeking to hold the polluters responsible.
Zeldin has announced a comprehensive agenda to target PFAS pollution before it reaches drinking water systems while also offering support and guidance to PWS to effectively treat PFAS that enter their systems. Zeldin said, “we are tackling PFAS from all of EPA’s program offices, advancing research and testing, stopping PFAS from getting into drinking water systems, holding polluters accountable, and providing certainty for passive receivers. This is just a start of the work we will do on PFAS to ensure Americans have the cleanest air, land, and water.”
The key aspects of EPA’s agenda to combat PFAS contamination include:
- Develop effluent limitations guidelines (ELGs) for PFAS manufacturers and metal finishers and evaluate other ELGs necessary for reduction of PFAS discharges
- Address the most significant compliance challenges and requests from Congress and drinking water systems related to national primary drinking water regulations for certain PFAS
- Determine how to better use Resource Conservation and Recovery Act (RCRA) authorities to address releases from manufacturing operations of both producers and users of PFAS
- Add PFAS to the Toxic Release Inventory (TRI) in line with Congressional direction from the 2020 National Defense Authorization Act
- Enforce Clean Water Act and TSCA limitations on PFAS use and release to prevent further contamination
- Use Safe Drinking Water Act authority to investigate and address immediate endangerment
- Achieve more effective outcomes by prioritizing risk-based review of new and existing PFAS chemicals
- Implement TSCA section 8(a)(7) to collect information, as Congress envisioned and consistent with TSCA, without overburdening small businesses and article importers.
- Work with Congress and industry to establish a clear liability framework that operates on polluter pays and protects passive receivers
Most Common PFAS and their Applications
The most commonly detected PFAS include: PFBA, PFPeA, PFHxA, PFBS, PFOA, PFOS, and PFHxS. All of them have been widely used because they resist heat, oil, stains, grease, and water.
Below is a breakdown of common industrial applications for each.
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Short-Chain PFAS - introduced as replacements for longer-chain compounds like PFOA and PFOS when the longer chain compounds were phased out in the early 2000s |
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Compound |
Common Uses |
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PFBA (Perfluorobutanoic acid) |
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PFPeA (Perfluoropentanoic acid) |
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PFHxA (Perfluorohexanoic acid) |
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PFBS (Perfluorobutanesulfonic acid)
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Long-Chain PFAS (Legacy Compounds) - heavily used from the 1950s–early 2000s before being phased out. |
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Compound |
Common Uses |
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PFOA (Perfluorooctanoic acid) |
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PFOS (Perfluorooctanesulfonic acid) |
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PFHxS (Perfluorohexanesulfonic acid) |
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Takeaways and Looking Forward
The UCMR 5 confirms the nationwide presence of PFAS in drinking water systems. While not a compliance yardstick, these data provide important previews of contaminants that may eventually face regulation or more stringent controls. Strong public support suggests these regulatory initiatives will progress, despite the broader de-regulatory climate.
Get In Touch
If your organization has concerns about the evolving PFAS regulatory environment, STP’s compliance information services can help. The STP Compliance Suite empowers your EHS team to track and manage the PFAS requirements that impact your global operations in one place, saving time and giving you piece of mind that comes with continuous, proactive compliance. STP’s regulatory monitoring services tracks emerging and final PFAS regulations globally so you can stay ahead of the changes. Your EHS team can use STP’s audit protocols to perform regulatory self-assessments to identify compliance gaps and manage them to closure. Contact us to learn more.
About the Author
Frank Skiba is the Director of Product Management at STP ComplianceEHS, where he has spent the past four years leading the development of compliance and sustainability solutions that help organizations navigate complex environmental, health, and safety (EHS) requirements. He focuses on bringing innovative tools to market that enable companies to improve regulatory compliance, strengthen sustainability performance, and protect workers and communities.
Frank enjoys collaborating with clients to solve complex challenges using industry best practices and emerging technology trends. His work centers on building practical, effective solutions that help organizations operate more safely while advancing environmental stewardship.
Before joining STP, Frank developed extensive experience in environmental compliance and regulatory technology, working with organizations to translate evolving regulations into actionable compliance strategies. He is a graduate of Vermont Law and Graduate School, a leading institution for environmental law and policy.
As a product leader, Frank has managed global teams and fostered collaborative environments that empower professionals to innovate and succeed while delivering tools that support safer workplaces and cleaner, more sustainable communities.