PFAS

What Are PFAS and Why Are They in Drinking Water? Per- and polyfluoroalkyl substances—PFAS—are a family of more than 14,000 synthetic chemicals characterized by extremely strong carbon-fluorine bonds that do not break down in the environment. This persistence earned them the name “forever chemicals.” They have been manufactured since the 1940s for use in nonstick cookware, waterproof textiles, food packaging, firefighting foam (aqueous film-forming foam, or AFFF), and hundreds of industrial applications. PFAS enter drinking water supplies through multiple pathways: discharge from manufacturing facilities, leaching from landfills containing PFAS-laden consumer products, runoff from areas where AFFF firefighting foam was used, and application of PFAS-contaminated biosolids to agricultural land. Once in groundwater, PFAS migrate freely because they are highly soluble and resistant to the natural degradation processes that break down most organic contaminants. The health concerns are well-documented. Epidemiological studies have linked PFAS exposure to increased risk of kidney and testicular cancer, thyroid disease, liver damage, immune system suppression, and developmental effects in children. A 2023 National Academies of Sciences report concluded that blood PFAS concentrations above 2 nanograms per milliliter are associated with clinically meaningful increases in cancer risk, while concentrations above 10 ng/mL substantially elevate risks for multiple health endpoints. What Did the Original 2024 EPA PFAS Rule Require? In April 2024, the EPA finalized the first-ever enforceable national drinking water standards for PFAS under the Safe Drinking Water Act. The rule established legally binding Maximum Contaminant Levels for six individual PFAS compounds and a hazard index for PFAS mixtures: PFAS Compound MCL (2024 Final Rule) 2026 Revision Status PFOA (perfluorooctanoic acid) 4 ppt Retained PFOS (perfluorooctane sulfonic acid) 4 ppt Retained PFHxS (perfluorohexane sulfonic acid) 10 ppt Rescinded PFNA (perfluorononanoic acid) 10 ppt Rescinded PFBS (perfluorobutane sulfonic acid) Hazard Index = 1 Rescinded GenX (HFPO-DA) 10 ppt Rescinded The original compliance timeline required public water systems to complete initial monitoring by 2027 and achieve full compliance with MCLs by 2029. What Changed in the 2026 EPA PFAS Rule Revisions? The 2026 revisions represent a significant narrowing of the original rule’s scope. Under the revised framework: PFOA and PFOS MCLs Remain at 4 ppt The enforceable limits for the two most widely studied and most frequently detected PFAS compounds are unchanged. PFOA and PFOS are the “legacy” long-chain PFAS that were the primary constituents of 3M’s Scotchgard and DuPont’s Teflon manufacturing processes. They are also the dominant PFAS compounds found in AFFF firefighting foam contamination plumes. Four Additional PFAS MCLs Rescinded The MCLs for PFHxS, PFNA, PFBS (as part of the hazard index), and GenX (HFPO-DA) have been rescinded. The stated rationale centers on concerns about the scientific basis for setting enforceable limits at the levels specified in the original rule, as well as cost-benefit considerations for water systems. This does not mean these compounds are safe—it means the federal government has elected not to regulate them with enforceable limits at this time. Compliance Deadline Extended to 2031 The deadline for public water systems to achieve compliance with the remaining PFOA and PFOS MCLs has been pushed from 2029 to 2031. Monitoring requirements have also been adjusted, with initial monitoring now expected to begin by 2028. What the Revisions Do Not Change Several important elements remain in force. The MCL Goals (MCLGs) for PFOA and PFOS remain at zero, reflecting the EPA’s assessment that no level of exposure is without risk. State-level PFAS regulations, which in many cases are more stringent than federal rules, are unaffected by the federal revisions. States including Michigan, New Jersey, Vermont, Massachusetts, and New Hampshire have their own enforceable PFAS standards that continue to apply. How Does PFAS Contamination Affect Utah? Utah’s PFAS contamination landscape is closely tied to military activity. Hill Air Force Base, located in Davis and Weber Counties just north of Salt Lake City, has been a significant source of PFAS groundwater contamination due to decades of AFFF firefighting foam use during training exercises and emergency response operations. The Department of Defense has identified multiple contamination plumes in the vicinity of the base, with PFOA and PFOS concentrations in some monitoring wells exceeding 10,000 ppt—more than 2,500 times the EPA’s MCL. The Utah Department of Environmental Quality (UDEQ) has conducted sampling at additional locations across the state, including airports, fire training facilities, and industrial sites where AFFF was historically used. Contamination has been confirmed at several locations along the Wasatch Front, including areas in Davis County, Weber County, and Salt Lake County. For commercial and industrial facilities drawing groundwater in affected areas, PFAS is not a theoretical concern. Even facilities using municipal water may be affected, as some smaller public water systems source from wells that intersect PFAS plumes. The extended compliance deadline to 2031 gives water utilities additional time, but it does not change the fundamental reality that PFAS-contaminated water will eventually need to be treated. How Does Reverse Osmosis Remove PFAS from Water? Reverse osmosis is the most effective commercially proven technology for removing PFAS from drinking water and process water. RO membranes operate by forcing water through a semi-permeable barrier with pore sizes in the range of 0.0001 microns (0.1 nanometers). PFAS molecules, even the smaller short-chain varieties, are significantly larger than these pores and are rejected at very high rates. Published research and field testing data consistently demonstrate the following PFAS rejection rates for properly designed RO systems: PFAS Compound Chain Length RO Rejection Rate PFOA 8 carbons (long-chain) 99%+ PFOS 8 carbons (long-chain) 99%+ PFHxS 6 carbons (short-chain) 96-99% PFNA 9 carbons (long-chain) 99%+ PFBS 4 carbons (short-chain) 95-98% GenX (HFPO-DA) Short-chain ether 96-99% The key advantage of RO over granular activated carbon (GAC) and ion exchange—the other two EPA-recognized treatment technologies for PFAS—is that RO removes all PFAS compounds simultaneously, including the shorter-chain varieties that break through GAC beds relatively quickly. GAC is effective for long-chain PFAS like PFOA and PFOS but requires frequent media replacement when short-chain PFAS are present. Ion exchange resins are more effective than GAC for short-chain PFAS but are

PFAS Contamination Has Moved From an Obscure Industrial Problem to a Household Concern—and the Solutions Are More Accessible Than You Think If you’ve followed water quality news over the past few years, you’ve probably seen the term “forever chemicals” more times than you can count. Per- and polyfluoroalkyl substances—PFAS for short—are a family of roughly 15,000 synthetic chemicals that have been manufactured since the 1940s. They show up in nonstick cookware, food packaging, firefighting foam, waterproof clothing, and thousands of other consumer and industrial products. They also show up in drinking water supplies across the country, and getting them out isn’t as simple as running water through a carbon filter. The EPA finalized its first-ever legally enforceable PFAS drinking water standards in April 2024, setting maximum contaminant levels (MCLs) at 4 parts per trillion (ppt) for PFOA and PFOS—two of the most studied and most toxic PFAS compounds. That’s 4 parts per trillion. To put that number in perspective, one part per trillion is equivalent to a single drop of water in 20 Olympic swimming pools. At those concentration levels, conventional water treatment methods struggle. But reverse osmosis doesn’t. RO membranes consistently achieve 90-99% rejection of PFAS compounds across the full molecular weight range, making RO the most reliable point-of-use and point-of-entry treatment technology for PFAS removal currently available. What Are PFAS, and Why Are They Called “Forever Chemicals”? PFAS molecules share a common structure: chains of carbon atoms bonded to fluorine atoms. The carbon-fluorine bond is one of the strongest in organic chemistry, which is exactly why these compounds were invented—they resist heat, water, oil, and chemical degradation. That same stability means they persist in the environment essentially forever. There is no known natural process that breaks down most PFAS compounds. The Two You’ve Heard Of: PFOA and PFOS Perfluorooctanoic acid (PFOA) was used in manufacturing Teflon. Perfluorooctane sulfonate (PFOS) was the active ingredient in 3M’s Scotchgard. Both are “long-chain” PFAS with 8 carbon atoms. Major manufacturers phased them out voluntarily between 2002 and 2015, but they persist in soil, groundwater, and human blood at measurable levels decades later. The Replacements Aren’t Necessarily Better When industry stopped making PFOA and PFOS, they switched to shorter-chain alternatives like GenX (HFPO-DA), PFBS, and PFHxS. Early marketing positioned these as safer replacements. The science has since caught up: many short-chain PFAS are just as persistent as their predecessors, and some studies suggest they may be equally toxic at chronic exposure levels. The EPA’s 2024 regulations address GenX and PFBS alongside the legacy compounds. Where PFAS Contamination Comes From PFAS enter water supplies through several pathways: Military bases and airports — Aqueous film-forming foam (AFFF) used in firefighting training has contaminated groundwater near hundreds of military installations and civilian airports. The Department of Defense has identified over 700 sites with known or suspected PFAS contamination. Industrial manufacturing — Facilities that manufactured or used PFAS (chemical plants, chrome plating, semiconductor fabrication) have contaminated local water supplies through air emissions and wastewater discharge. Landfills — Consumer products containing PFAS break down in landfills, and leachate carries PFAS into groundwater. A 2023 study found PFAS in leachate from 95% of U.S. landfills tested. Wastewater treatment plants — Conventional wastewater treatment doesn’t remove PFAS. Treated effluent discharged to rivers and streams introduces PFAS into downstream drinking water sources. Biosolids and agricultural runoff — PFAS-contaminated sewage sludge applied as fertilizer has contaminated farmland and groundwater in Maine, Michigan, and other states. Health Effects: What the Research Shows The health risks associated with PFAS exposure are well-documented and concerning: Cancer — PFOA is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC). Epidemiological studies near the DuPont Washington Works plant in West Virginia linked PFOA exposure to kidney cancer, testicular cancer, and thyroid disease. Immune system suppression — Studies show reduced vaccine response in children with elevated PFAS blood levels. A 2023 National Academies report concluded that PFAS exposure decreases antibody response to vaccines. Thyroid disease — PFAS interfere with thyroid hormone production, with effects documented at blood levels common in the general U.S. population. Reproductive effects — Associations with reduced fertility, preeclampsia, and low birth weight. Liver damage — Elevated liver enzymes and non-alcoholic fatty liver disease linked to PFAS exposure. Cholesterol — Even low-level PFAS exposure is associated with increased total cholesterol and LDL levels. The EPA set its MCLs at 4 ppt specifically based on cancer risk assessments and immune system effects. At that level, the lifetime cancer risk from PFOA or PFOS exposure through drinking water is approximately 1 in 10,000—the threshold the EPA uses for establishing health-based standards. How Reverse Osmosis Removes PFAS RO works by forcing water through a semi-permeable membrane with pore sizes in the range of 0.0001 microns. PFAS molecules, even the smallest short-chain variants, are too large to pass through these pores. The rejection mechanism is primarily size exclusion combined with charge repulsion—most PFAS carry a negative charge at drinking water pH levels, and TFC (thin-film composite) RO membranes also carry a negative surface charge, creating electrostatic repulsion. Rejection Rates by PFAS Type Published peer-reviewed studies and EPA testing data show the following rejection rates for RO membranes: PFOA (C8, 414 g/mol) — 96-99% rejection PFOS (C8, 500 g/mol) — 97-99.9% rejection PFHxS (C6, 400 g/mol) — 95-99% rejection PFBS (C4, 300 g/mol) — 90-97% rejection GenX / HFPO-DA (C6, 330 g/mol) — 93-98% rejection PFBA (C4, 214 g/mol) — 90-95% rejection (lowest among commonly tested PFAS) The trend is clear: larger, longer-chain PFAS are rejected at higher rates, while smaller short-chain compounds still achieve 90%+ rejection. For a water supply contaminated at 100 ppt total PFAS, a quality RO system will produce permeate at 1-10 ppt—well below the EPA MCLs. GAC vs. RO: Which Technology Is Better for PFAS? Granular activated carbon (GAC) is the other primary technology used for PFAS removal. Here’s how it compares to RO: Factor Granular Activated Carbon (GAC) Reverse Osmosis (RO) Long-chain PFAS removal Excellent (95-99%) Excellent