PFAS: the "forever chemicals" in drinking water

PFAS are a family of thousands of man-made chemicals nicknamed "forever chemicals," because they are built around one of the strongest bonds in chemistry and barely break down, in the environment or in your body. For decades they went almost entirely unregulated in drinking water. In 2024 that changed: the EPA set the first enforceable federal PFAS limits, and for the two most-studied compounds, the health goal it set was zero.

What PFAS actually are

PFAS stands for per- and polyfluoroalkyl substances. Since the 1940s they have been used to make products resist heat, oil, grease, water and stains: nonstick cookware, waterproof and stain-resistant fabrics, grease-proof food packaging, cosmetics, and firefighting foams used at airports and military bases. That same durability is the problem. The carbon-fluorine bond that makes them useful also makes them extraordinarily persistent, so they accumulate in soil, in groundwater, and in people.

The two most-studied members are PFOA and PFOS. Both were phased out of U.S. manufacturing years ago, yet they are still detected widely because they simply do not go away. The U.S. CDC has reported that PFAS are found in the blood of the vast majority of people tested.

Why the health concern is serious

Because PFAS build up in the body over years, the concern is chronic exposure rather than any single glass of water. The clearest evidence came from the C8 Science Panel, a group of independent epidemiologists appointed as part of the landmark litigation over PFOA contamination. After studying tens of thousands of exposed residents, the panel found a "probable link" between PFOA exposure and six conditions, the same conditions now central to the ongoing PFAS lawsuits:

• Kidney cancer
• Testicular cancer
• Ulcerative colitis, a chronic inflammatory bowel disease
• Thyroid disease
• High cholesterol
• Pregnancy-induced hypertension (including preeclampsia)

Building on that work, in 2023 the World Health Organization's cancer agency (IARC) classified PFOA as carcinogenic to humans (Group 1), its highest category, and PFOS as possibly carcinogenic (Group 2B). PFAS are also recognized endocrine disruptors: they interfere with the body's hormone systems, which is part of why they are tied to thyroid disease and to effects on reproduction and development. The EPA and the federal ATSDR (Agency for Toxic Substances and Disease Registry) additionally link higher exposure to immune effects, including a reduced vaccine response in children, changes in liver enzymes, and lower infant birth weight.

These are associations drawn from population and legal-case studies, not a guarantee that any one person will be harmed. But the weight of evidence is why regulators moved, and why they moved hard.

The 2024 EPA rule: a health goal of zero

In April 2024 the EPA finalized the first-ever national, legally enforceable drinking-water standards for PFAS. As with every contaminant, the EPA set two kinds of numbers (if you have read our piece on legal versus ideal, this will look familiar):

• The health goal (MCLG) for PFOA and PFOS is zero. The EPA concluded there is no level of these two compounds in drinking water that is considered free of health risk.
• The enforceable limit (MCL) for PFOA and for PFOS is 4 parts per trillion each, the lowest level reliably measurable in a lab. The rule also set enforceable limits for several other PFAS (including GenX chemicals, PFHxS and PFNA).

To put 4 parts per trillion in perspective, that is roughly four drops in a volume of water large enough to fill many Olympic swimming pools. The gap between "zero is the goal" and "4 parts per trillion is what we can enforce" is, once again, the space between ideal and legal. PFAS rules have also continued to be revised and litigated at the federal level, so the exact enforceable figures for some compounds may change; the direction of the science, and the zero health goal for PFOA and PFOS, has not.

Are PFAS in Arizona water?

PFAS are a national issue, and Arizona is not exempt. They have been detected in some Valley-area water supplies, with the clearest hotspots tied to sites where PFAS-containing firefighting foam was used heavily over the years, such as military installations and airports. Because contamination is local and depends on the specific source and wells that serve your home, the only way to know your own exposure is to look at your provider's testing and, ideally, to test the water at your tap.

It's not only what you drink

Focusing on drinking water misses part of the picture. You are also exposed to what is in your water every time you shower and bathe, through two routes at once: your skin absorbs some compounds directly, and hot water releases others into the air as vapor that you then breathe in. A hot shower in a closed bathroom is close to a worst case for both.

This route is most significant for the volatile contaminants riding along in the same tap water, above all chlorine and the disinfection byproducts it forms, the trihalomethanes (TTHMs). These evaporate readily in a hot shower, and research has found that inhalation and skin absorption during showering and bathing can account for a substantial share of a person's total exposure to volatile compounds like chloroform (a TTHM), in some cases rivaling how much comes from drinking the water. It is a big part of the "pool smell" people notice standing in a hot shower.

PFAS themselves are not volatile, so they do not steam into the air the way TTHMs do. But they are not irrelevant here either: emerging research, including a 2024 University of Birmingham study, indicates that a range of PFAS can be absorbed through human skin. The practical takeaway is the same for both, meaningful exposure happens at every tap in the house, not just the one you drink from, which is the whole case for treating the entire home rather than the kitchen alone.

How to remove PFAS from your water

The good news: PFAS are treatable at home, and the EPA itself names the effective technologies. The two most relevant for a household are:

Reverse osmosis (RO)

An under-sink RO system forces water through an ultra-fine membrane that rejects PFAS along with a broad range of other dissolved contaminants. It is widely regarded as one of the most effective ways to reduce PFAS in the water you drink and cook with, which is where it matters most.

Activated carbon filtration

Granular activated carbon adsorbs longer-chain PFAS such as PFOA and PFOS, and is one of the technologies the EPA recognizes for PFAS reduction. Carbon also handles the chlorine and disinfection byproducts that come with Valley water, so every tap benefits.

Here is where it matters for us: every Aera system carries activated carbon media as standard, one of the EPA-recognized technologies for reducing PFAS. That means an Aera system doesn't just soften your water, it dramatically reduces PFAS at every tap in the home, not only at the kitchen sink. The Signature blends carbon into the tank; the flagship Reserve runs a dedicated carbon tank ahead of the resin for the deepest whole-home reduction. For the water you actually drink and cook with, we pair that with an under-sink reverse-osmosis system, which pushes PFAS reduction as close to the EPA's zero health goal as a home realistically can.

(A quick clarification, since it comes up: the ion-exchange softening step itself is what removes hardness minerals, not PFAS. The PFAS reduction comes from the carbon that every Aera system includes, and, for drinking water, from RO.)

PFAS are one of the strongest arguments there is for treating the water you actually drink, rather than trusting that "no violation" means "nothing there." A free in-home water assessment is the simplest way to understand your situation and build the right system for it.