PFAS US Contamination Map

This PFAS contamination map visualizes detections of per- and polyfluoroalkyl substances — commonly called “forever chemicals” — in public drinking water systems across the United States. Data comes directly from the EPA’s Unregulated Contaminant Monitoring Rule 5 (UCMR 5) program, which required utilities serving 3,300 or more people to test for 29 PFAS compounds between 2023 and 2025. Each dot on the map represents a water system with at least one detection at or above the EPA’s minimum reporting level.

How to Use This Map

Getting Started

The map loads PFAS detections at or above the UCMR minimum reporting level (MRL) for all US states. Red dots indicate detections at or above the MRL; orange dots indicate detections below it. Zoom in and click any dot to open a popup with the water system name, state, population served, contaminant detected, measured concentration in nanograms per liter (ng/L), whether the result exceeded the EPA health-based screening level (HBSL), and the sample collection date.

Filtering by State

Use the State dropdown to filter detections to a single state. This is useful for a closer look at contamination in specific regions — for example, filtering to California reveals detections concentrated around the Central Valley and Southern California, while Michigan shows clusters near industrial areas and former military sites including Wurtsmith Air Force Base. States with historically high detection counts include New Jersey, Pennsylvania, Ohio, New York, Texas, Florida, North Carolina, and Illinois. Selecting a state reloads only that state’s data, which is faster for detailed exploration.

PFAS in US Drinking Water: What the Data Shows

PFAS are a group of more than 12,000 synthetic chemicals that have been manufactured and used in industrial and consumer products since the 1940s. They are called “forever chemicals” because they do not break down naturally in the environment or the human body. The primary sources of PFAS in drinking water include aqueous film-forming foam (AFFF) used at military bases and airports, industrial discharge from manufacturers of PFAS-containing products, landfill leachate, and agricultural application of PFAS-contaminated biosolids.

The UCMR 5 dataset represents the most comprehensive national picture of PFAS in drinking water ever assembled. States with the highest number of detections tend to cluster around legacy industrial corridors, military installations, and densely populated areas with large numbers of utilities. New Jersey has long been a focal point due to its industrial history and high water system density. Michigan has faced extensive remediation around PFAS-contaminated groundwater near former military sites. California detections are widespread, partly driven by firefighting foam use at Air Force bases across the state. Colorado, Alabama, and Massachusetts have also reported elevated contamination levels near military and industrial sites.

PFAS contamination in groundwater is closely linked to aquifer vulnerability. Areas that rely heavily on shallow groundwater for drinking water supply are at greatest risk — you can explore the aquifer systems underlying these detections with our interactive US aquifer map. Where PFAS has leached into soil and groundwater over decades, it often co-occurs with other hazardous contamination — many PFAS-heavy sites appear in or near locations listed on the EPA Superfund National Priorities List.

Health Effects and Regulatory Context

Exposure to PFAS through drinking water is associated with a range of serious health effects, including increased risk of certain cancers (kidney and testicular cancer in particular), thyroid disease, high cholesterol, immune system disruption, and developmental effects in infants and children. The US National Toxicology Program concluded in 2023 that PFOA and PFOS — two of the most studied PFAS compounds — are “presumed to be an immune hazard to humans” at very low exposure levels.

In April 2024, the EPA finalized the first-ever national drinking water standards for six PFAS compounds, setting a maximum contaminant level (MCL) of 4 parts per trillion (ppt) for PFOA and PFOS individually, and 10 ppt for PFNA, PFHxS, and HFPO-DA. Water utilities have until 2029 to comply. This map shows UCMR 5 monitoring data, which predates final MCL enforcement — many detections shown here would require treatment under the new rules.

Air quality is another vector for PFAS exposure, particularly near industrial facilities that manufacture or use PFAS compounds — our global air quality map tracks PM2.5 and other pollutants from industrial sources. For a broader picture of industrial contamination risk, the US nuclear power stations map shows the distribution of nuclear facilities, some of which have associated contamination concerns.

Data Sources and Limitations

Data is sourced from the EPA PFAS Analytic Tools, which serves UCMR 5 monitoring results for public water systems. The dataset covers samples collected between 2023 and 2025 under the fifth cycle of the Unregulated Contaminant Monitoring Rule.

• This map shows only detections at or above the EPA minimum reporting level (MRL). Detections below the MRL may still represent meaningful exposure at some concentration thresholds.
• Small water systems serving fewer than 3,300 people were not required to monitor under UCMR 5, so contamination in rural and small-community water supplies is likely underrepresented.
• Private wells are entirely outside the scope of UCMR monitoring and are not shown. Residents on private wells in high-risk areas should consider independent testing.
• The dataset represents point-in-time sampling, not continuous monitoring. Concentrations may have changed since the sample was collected.

Frequently Asked Questions

What are PFAS and why are they called “forever chemicals”?

PFAS (per- and polyfluoroalkyl substances) are a class of more than 12,000 synthetic chemicals characterized by extremely strong carbon-fluorine bonds. This bond makes them resistant to heat, water, and oil — but also means they do not break down in the environment or in human tissue, accumulating over time. They have been used in non-stick cookware (Teflon), waterproof clothing, food packaging, stain repellents, and firefighting foam since the 1940s.

Which US states have the most PFAS detections in drinking water?

Based on UCMR 5 data, states with the highest detection counts include New Jersey, California, Pennsylvania, Ohio, New York, Michigan, Texas, Florida, Illinois, and North Carolina. States with significant military installations — including Alabama (Anniston Army Depot), Colorado (Peterson Air Force Base), and Massachusetts (Otis Air National Guard Base) — also show elevated contamination. However, detection counts partly reflect the number of water utilities monitored, so densely populated states with many systems naturally show more detections.

What is the MRL (minimum reporting level) shown on this map?

The MRL is the lowest concentration that laboratories are required to accurately measure and report under UCMR 5. For PFOA and PFOS, the MRL is 4 ng/L (nanograms per liter, or parts per trillion). This map shows detections at or above the MRL. Note that EPA’s final drinking water MCLs (4 ppt for PFOA and PFOS) align with the UCMR 5 MRL, meaning most detections shown here would be subject to treatment requirements under current regulations.

What should I do if my water utility appears on this map?

A detection on this map means PFAS were measured at or above the MRL in a sample from that system. Check your utility’s most recent Consumer Confidence Report (CCR), which is required to disclose UCMR results. If you have concerns, you can also request current testing results directly from your water provider. For private well owners in affected areas, consider independent laboratory testing — the EPA’s drinking water health advisories include guidance on PFAS and other contaminants of concern.

Does PFAS contamination affect flood-prone areas differently?

Yes — flooding can mobilize PFAS from contaminated soil and industrial sites into surface water and groundwater used for drinking. In areas where PFAS-contaminated land floods regularly, the risk of drinking water contamination is compounded. You can cross-reference PFAS detections with flood risk using our FEMA flood zones map to identify communities facing overlapping hazards.

Is bottled water safe from PFAS?

Bottled water is regulated by the FDA, not EPA, and historically faced less stringent PFAS testing requirements than public water systems. Some bottled water products have been found to contain detectable PFAS levels, particularly those sourced from groundwater in contaminated areas. Reverse osmosis and activated carbon filtration systems are effective at reducing PFAS concentrations in tap water.