DATA & RESEARCH
PFAS in Drinking Water: How Many Americans Are Affected by State
Last updated: April 18, 2026
More than 172 million Americans may be drinking water contaminated with PFAS — the synthetic "forever chemicals" linked to cancer, thyroid disease, and immune system damage. This page summarizes what the latest EPA and Environmental Working Group data show about which states are most affected, what the federal standards require, and what this means for people exploring legal options.
This page provides general educational information only and does not constitute medical or legal advice. Data is sourced from EPA UCMR 5 monitoring results and Environmental Working Group analysis.
What the EPA Data Shows
The EPA's Fifth Unregulated Contaminant Monitoring Rule, known as UCMR 5, required public water systems across the country to test for 29 PFAS compounds between 2023 and 2025. It is the most comprehensive federal PFAS testing effort ever conducted.
As results have come in, the picture has grown steadily more alarming. Early UCMR 5 data identified contamination at thousands of water systems. By mid-2025, the Environmental Working Group's analysis of cumulative EPA data estimated that over 172 million Americans face potential exposure to PFAS-contaminated drinking water — a number that has risen with each quarterly data release as more systems report results.
The CDC has detected PFAS in the blood of 99 percent of Americans tested, including newborns. Scientists attribute drinking water as one of the primary exposure pathways.
Which States Are Most Affected
PFAS contamination has been detected in every state except Arkansas, Hawaii, and North Dakota, according to NRDC analysis of UCMR 5 data published in July 2025. Contamination levels vary significantly depending on the concentration of military bases, airports, industrial facilities, and how aggressively each state has tested.
States that consistently appear in high-contamination analyses include:
| State | Key contamination factors | Notable context |
|---|---|---|
| California | Military bases, industrial sites, airports | Has proposed its own PFAS MCLs stricter than federal standards |
| Michigan | Industrial manufacturing, military installations | One of the first states to set enforceable PFAS drinking water limits |
| New York | Manufacturing, airports, military | Has established MCLs and is proposing additional restrictions |
| North Carolina | GenX/Chemours manufacturing | GenX contamination affected drinking water for approximately 500,000 people |
| Pennsylvania | Industrial facilities, military | Among states proposing MCLs aligned with EPA 2024 rule |
| New Jersey | Dense industrial corridor, military sites | Set some of the earliest and strictest state PFAS limits in the country |
| Colorado | Air Force bases, AFFF use | Military-adjacent communities have seen significant groundwater contamination |
| Alabama | 3M manufacturing, industrial discharge | Site of major early PFAS litigation involving 3M and water utilities |
This table reflects general patterns from publicly available data. For current contamination data specific to your water system, the EPA's PFAS Analytic Tools and the EWG's interactive contamination map are the most up-to-date sources.
The Federal Standard — and What Is Happening to It
In April 2024, the EPA finalized the first-ever national drinking water limits for six PFAS compounds. The rule set a maximum contaminant level of 4 parts per trillion for PFOA and PFOS individually — an extraordinarily low threshold that reflects how toxic these chemicals are considered at even trace levels.
However, by May 2025, the EPA under the Trump administration announced it would rescind the limits for four of the six covered PFAS — PFHxS, PFNA, GenX, and PFBS — while retaining the PFOA and PFOS limits. Compliance deadlines for PFOA and PFOS were also extended from 2029 to 2031.
The rollback is legally contested. Opponents argue it violates the Safe Drinking Water Act's anti-backsliding provision, which generally prohibits the EPA from weakening existing drinking water standards. As of early 2026, litigation over the 2024 rule is ongoing in federal court.
Many states have responded by advancing their own stricter standards. States including California, New York, Vermont, Washington, and Wisconsin are among those proposing or finalizing PFAS limits that parallel or exceed the 2024 federal rule.
How PFAS Gets Into Drinking Water
PFAS contamination in drinking water typically comes from one or more of these sources:
- Military bases and airports — Aqueous film-forming foam (AFFF), used for decades in fire suppression training and emergencies, is one of the primary sources of PFAS groundwater contamination nationwide
- Industrial manufacturing — Facilities that produced or used PFAS in products like nonstick coatings, stain-resistant textiles, and firefighting equipment discharged PFAS into surrounding soil and waterways
- Landfills — Products containing PFAS leach into groundwater from landfill sites over time
- Wastewater treatment plants — PFAS pass through conventional treatment processes and are discharged into surface water, which then enters drinking water sources
- Agricultural use of sewage sludge — Biosolids applied to farmland as fertilizer can contain PFAS that migrate into groundwater
Because PFAS do not break down naturally, contamination that entered groundwater decades ago is still present today and will persist for the foreseeable future without active remediation.
Health Concerns Linked to PFAS Exposure
The EPA and public health agencies have linked long-term PFAS exposure to a range of serious health conditions. The health concerns most commonly discussed in connection with PFAS litigation include:
- Kidney cancer
- Testicular cancer
- Thyroid disease
- Immune system suppression
- Liver damage
- High cholesterol
- Reproductive and developmental concerns, including effects on fetal development
Because PFAS accumulate in the body over time and exposure often spans years or decades, many people do not connect a diagnosis to their water supply until long after the exposure occurred. This is one reason why filing deadlines in PFAS cases typically run from the date of diagnosis or discovery — not the date of original exposure.
For more on the illnesses commonly discussed in water contamination litigation, see Water Contamination Illnesses and Cancers Linked to Lawsuits.
What This Means for Legal Claims
The scale of PFAS contamination has produced one of the largest waves of environmental litigation in U.S. history. Lawsuits have been filed by individuals, municipalities, and state attorneys general against PFAS manufacturers, AFFF producers, and industrial operators.
In 2023, 3M agreed to pay up to $10.3 billion to settle claims from public water systems over PFAS contamination — one of the largest environmental settlements in history. DuPont and related entities separately agreed to pay approximately $1.185 billion to resolve similar claims from water utilities.
Individual claims — brought by people diagnosed with PFAS-linked illnesses — remain active and ongoing. These cases typically involve proving that the person was exposed to contaminated water over a significant period, that the exposure came from a specific source, and that a diagnosed condition may be connected to that exposure.
For a full overview of how these cases work, see PFAS Water Contamination Lawsuits, AFFF Firefighting Foam Lawsuits, and What Evidence Helps a Lawsuit?
How to Check If Your Water System Is Affected
Several free public tools let you search PFAS contamination data by location:
- EPA PFAS Analytic Tools (echo.epa.gov) — Search UCMR 5 monitoring results by water system, state, or zip code
- EWG Tap Water Database (ewg.org/tapwater) — Consumer-facing tool showing contaminants detected in local water systems
- EWG PFAS Contamination Map (ewg.org/interactive-maps/pfas_contamination) — Interactive map of 9,728 known contamination sites
- NRDC PFAS Map (nrdc.org) — Shows systems with UCMR 5 results above EPA thresholds by congressional district
If you find your water system in these databases, your annual Consumer Confidence Report — required to be sent to customers each year — will also include the most recent testing results.
Common Questions
How many Americans are affected by PFAS in drinking water?
According to EPA monitoring data analyzed by the Environmental Working Group, over 172 million Americans may be at risk of drinking PFAS-contaminated water. Testing under UCMR 5 is ongoing and the number continues to rise as more water systems report results. Learn more →
Which states have the most PFAS contamination in drinking water?
States with high concentrations of military bases, industrial facilities, and airports tend to have the most contaminated water systems. PFAS have been detected above EPA thresholds in 47 of 50 states, with only Arkansas, Hawaii, and North Dakota showing no detections above current thresholds. Learn more →
What is the EPA's legal limit for PFAS in drinking water?
In April 2024, the EPA finalized limits of 4 parts per trillion for PFOA and PFOS. In May 2025, the EPA announced it would maintain those two limits but rescind limits for four other PFAS. Compliance deadlines have been extended to 2031. Several states are advancing their own stricter standards. Learn more →
How does PFAS contamination connect to lawsuits?
People diagnosed with certain cancers, thyroid disease, or other conditions after long-term exposure to PFAS-contaminated water may be able to explore legal claims. Filing deadlines typically run from the date of diagnosis, not original exposure. Learn more →
Exploring your legal options?
If you or a family member may have been affected by PFAS-contaminated drinking water, our PFAS lawsuit guide explains how these cases work and what steps people typically take first.
Sources
Data and statistics on this page are drawn from the following public sources. Lawsuit Informer is an educational website and does not conduct independent water testing.
- U.S. EPA — PFAS National Primary Drinking Water Regulation
- U.S. EPA — PFAS Analytic Tools (UCMR 5 Data)
- Environmental Working Group — PFAS Contamination Map (9,728 Sites)
- Environmental Working Group — 172 Million Americans at Risk (2025)
- NRDC — New Maps Show Most Congressional Districts Have a PFAS Problem (July 2025)
- U.S. GAO — Persistent Chemicals: EPA Should Use New Data to Analyze Demographics of Communities with PFAS
- BCLP Law — PFAS Drinking Water Standards: State-by-State Regulations (June 2025)
