What is PFOS + PFOA + PFHxS + PFNA and Why Does It Matter?

PFAS Chemicals (PFOS, PFOA, PFHxS, and PFNA)

PFAS — short for per- and polyfluoroalkyl substances — are a group of man-made chemicals that have been used in manufacturing since the 1940s. PFOS and PFOA were once common in nonstick cookware, stain-resistant fabrics, and food packaging. PFHxS and PFNA showed up in firefighting foam, waterproof clothing, and industrial processes. Because these chemicals don't break down naturally, scientists often call them "forever chemicals." They seep into groundwater through industrial discharge, military base runoff, and landfill leachate — then travel through municipal water systems straight to your tap.

The health concerns around PFAS are serious and well-documented. Long-term exposure has been linked to thyroid disease, kidney and testicular cancer, immune system suppression, and hormone disruption, according to the EPA and the National Toxicology Program. Children are especially vulnerable. Even low-level exposure can interfere with vaccine response and normal development. The average level detected across Washington's 171 water systems sits at 13.039 parts per trillion (ppt). That sounds small, but PFAS accumulate in the body over time — meaning daily exposure adds up, even at trace levels.

Regulation of PFAS chemicals has moved slowly, but that's starting to change. In April 2024, the EPA finalized the first-ever federal limits for PFAS in drinking water. The new Maximum Contaminant Level (MCL) is set at 4 ppt for PFOA and PFOS individually. For PFNA, PFHxS, and a combination index that includes all four chemicals covered here, separate limits also apply. The Environmental Working Group (EWG) recommends an even stricter health guideline of just 1 ppt for the combined group, based on independent research into cancer and immune risks. None of Washington's 171 affected systems currently exceed the EWG guideline — but the maximum detected level of 120.8 ppt is a clear reminder that some locations face much higher concentrations than the statewide average suggests.

Washington state has unique exposure risks tied to its geography and history. Military installations like Joint Base Lewis-McChord have used PFAS-containing firefighting foam for decades, contaminating surrounding groundwater. Boeing and other aerospace manufacturers have also contributed to industrial PFAS loading in the Puget Sound region. Rural communities that rely on smaller water systems tend to have less filtration infrastructure, making them more vulnerable to elevated levels. All 171 systems with detected PFAS are located in Washington — a reflection of both the state's industrial footprint and its aggressive testing program. More testing doesn't always mean more contamination. Sometimes it just means more transparency.

The good news is that effective filtration options exist. Reverse osmosis (RO) filtration removes up to 99% of PFAS compounds from drinking water, making it one of the most reliable choices for households concerned about these chemicals. Activated carbon filters — particularly those using granular activated carbon (GAC) — also reduce PFAS levels significantly, though not as completely as RO systems. Standard pitcher filters and basic faucet attachments typically do not remove PFAS effectively. If you're in Washington or any area with detected PFAS, an under-sink reverse osmosis system is worth serious consideration. Echo Water's RO systems are independently tested to NSF/ANSI 58 standards, specifically for PFAS reduction. Pairing filtration with regular water quality testing gives you the clearest picture of what's actually coming out of your tap — and the confidence to know your family is protected.

Regulatory Standards for PFOS + PFOA + PFHxS + PFNA

Cities With the Highest PFOS + PFOA + PFHxS + PFNA Levels

States Most Affected by PFOS + PFOA + PFHxS + PFNA

Frequently Asked Questions

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