Common questions about PFAS in drinking water

PFAS (per- and polyfluoroalkyl substances) are a family of more than 12,000 man-made chemicals used since the 1940s in non-stick cookware, waterproof clothing, food packaging, and firefighting foam. They're called "forever chemicals" because they don't break down in the environment or in the human body.

Possibly. EPA's UCMR 5 testing detected PFAS in over 6,100 public water systems across the US. To check yours, enter your ZIP code at checkpfas.com — our data covers the 14,090 ZIP codes served by systems with detections.

EPA finalized Maximum Contaminant Levels (MCLs) in April 2024: 4 parts per trillion (ppt) each for PFOA and PFOS, plus 10 ppt each for PFHxS, PFNA, and HFPO-DA (GenX). Public water systems have until 2027 to complete monitoring and 2029 to install treatment if any MCL is exceeded. EPA announced a reconsideration of the four 10 ppt limits in May 2025; the PFOA and PFOS limits are stable.

Two filter technologies reliably remove PFAS at home: reverse osmosis (RO) and activated carbon block. Look specifically for NSF/ANSI 58 or NSF/ANSI 53 certification with "PFOA & PFOS reduction" listed. Standard pitcher and refrigerator filters typically do NOT remove PFAS unless explicitly certified.

Long-term PFAS exposure is linked to increased risk of kidney and testicular cancer, thyroid disease, high cholesterol, immune-system suppression, decreased vaccine response, pregnancy-induced hypertension, and lower birth weight. Children, pregnant women, and those drinking contaminated water for years face the highest risk.

Not necessarily. Independent testing has detected PFAS in many bottled water brands. The FDA does not currently require PFAS testing for bottled water. A certified home filter is generally a more reliable and cost-effective solution.

"Not detected" means the PFAS concentration in a sample was below the minimum reporting limit (MRL), which is approximately 1.5–2 ppt for most compounds. It does not mean literally zero PFAS — instruments have detection floors. It means concentrations are below the level where the current science indicates health concern.

A ZIP without data wasn't linked to a water system in EPA's UCMR 5 dataset. Common reasons: the area relies on private wells (not covered by UCMR 5), the system serves fewer than 25 people (small systems were exempt), or EPA's service-area mapping didn't link this ZIP to a tested utility. Browse by state or contact your local water authority for more information.

EPA's PFAS rules don't apply to private wells. Testing your own water is the only way to know. A certified lab running EPA Method 537.1 can test for the regulated PFAS compounds for around $300–$500. Your state's environmental agency typically maintains a list of certified labs. See our guide: PFAS in Private Wells.

The current data is from EPA UCMR 5, released January 2026, covering testing through December 2025. The EPA does not publish ongoing UCMR 5 updates. When the EPA releases revised or additional UCMR 5 data, we will update CheckPFAS within 30 days.