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PFAS in Drinking Water: A Scientist’s Guide For Your Home
March 6, 2025
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Eric Roy, PhD | Chief Scientist
I spent the early part of my career studying water chemistry in a lab, but I learned quickly that the most important questions come from people in crisis. Families in Flint who learned that their pipes were leaching lead. Communities across the world now discovering PFAS in their drinking water. Almost everyone asks the same question: Is my water safe?
The truth is complicated by a persistent gap between what is legal and what is safe. That gap is most obvious with PFAS.
Municipal water systems were built to deliver every drop of water to a legal standard. Those standards are set by regulators and elected officials who must balance the desire to remove toxic contaminants with the willingness to pay for the technology required to do it. The standard also applies to all of the water a municipality treats, even though it is common sense that we should think differently about the water we drink than the water we use to flush toilets.
As a scientist, I think about water safety the same way your body does: by focusing on exposure and toxicology, not negotiated regulations.
PFAS (per- and polyfluoroalkyl substances) are a family of synthetic chemicals used for decades because they have properties that make products resistant to heat, oil, grease, and water. They appear in nonstick cookware, food packaging, firefighting foam, clothing, carpets, and countless industrial applications.
Unlike lead, which leaches from pipes in the home, PFAS enter the drinking water supply before the treatment plant. Common pathways include:
There is no way around it. PFAS are toxic and linked to a range of health concerns:
Why Low Levels Matter
PFAS have biological half-lives measured in years. PFOS, for example, remains in the body for about five years. Even low concentrations in drinking water can cause the amount in your blood to accumulate over time.
Recent actions by the EPA show how difficult it is to regulate contaminants in drinking water. In April 2024, the EPA set the first federal standards for several PFAS compounds (PFOA, PFOS, PFHxS, PFNA, and GenX). In 2025, the agency shifted course, proposing the removal of several PFAS from the rule and extending compliance deadlines.
While federal standards are slow and uncertain, momentum has been building at the state level. States like Maine, Michigan, New Jersey, and Vermont have some of the strictest PFAS standards in the country and require utilities—and in some cases private wells—to be tested and remediated when PFAS exceed state thresholds.
The result is a patchwork system where your protection depends heavily on where you live. Many people remain unprotected simply because their state has not acted.
If you rely on a private well, none of these regulations apply to you. Your water is completely unregulated. There is no requirement for anyone to notify you of contamination, test your water, or fix a problem at your home. You are the utility.
To know what is in your water, you must collect and send a sample to an accredited lab that analyzes PFAS using EPA Method 533 or EPA Method 537.1.
This part is simple. You need to filter your water with a product that has been proven to reduce PFAS.
The only way to know if a product works is to look at third-party certifications. Do not overthink the technology (Reverse Osmosis vs. Carbon). There is enormous performance variability within each technology. Not all RO systems remove PFAS. Not all carbon systems remove PFAS.
The Certification You Need
You want PFAS reduction under NSF/ANSI Standard 53 or Standard 58, specifically for:
These certifications can be issued by NSF, WQA, or IAPMO.
The Scientist's Warning:
If a product does not carry this certification, you should assume it has not been proven effective. Some water filter companies use phrases like “filters contaminants” or “third-party laboratory tested,” which sound scientific but allow manufacturers to use incomplete or selective testing. NSF/ANSI certification requires testing throughout the entire useful life of the filter, which is critical for PFAS.
Once you verify certification, choose a system that fits your home and install it where you drink and cook with the water, since ingestion is the primary exposure pathway.
Can I boil PFAS out of water?
No. Boiling concentrates PFAS because water evaporates and PFAS remain.
Do refrigerator or pitcher filters remove PFAS?
Generally, no. Most use loose granular carbon designed for taste and odor removal and lack the contact time needed for PFAS adsorption.
Does PFAS leave the body?
Yes, but slowly. PFAS have biological half-lives measured in years. When you switch to filtered water, blood serum levels decline over time.
Is it safe to shower in water that contains PFAS?
Ingestion is the primary exposure pathway. Skin absorption is considered low, though reducing total exposure is always the prudent approach.
If You Are on City Water
If You Rely on a Private Well
If You Are Selecting a Filter
Look only at products certified to NSF/ANSI Standard 53 or Standard 58 for PFOA/PFOS or Total PFAS.
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