MyCleanWater
Contaminant Deep Dives·MyCleanWater Team

What Are PFAS? A Complete Guide to Forever Chemicals in Your Water

What Are PFAS?

PFAS (per- and polyfluoroalkyl substances) are a large group of over 14,000 synthetic chemicals that have been manufactured and used in various industries since the 1940s. They are commonly called "forever chemicals" because their carbon-fluorine bonds are among the strongest in organic chemistry — they do not naturally break down in the environment or in the human body.

Where Do PFAS Come From?

PFAS enter drinking water through several pathways:

  • Industrial discharge from manufacturing facilities that produce or use PFAS
  • Military bases and airports where PFAS-containing firefighting foam (AFFF) was used for decades
  • Wastewater treatment plants that receive PFAS-contaminated industrial or household waste
  • Landfills where PFAS-containing consumer products break down and leach into groundwater
  • Agricultural runoff from fields treated with PFAS-contaminated biosolids (sewage sludge used as fertilizer)

Health Effects of PFAS Exposure

Research has linked PFAS exposure to numerous health concerns:

  • Cancer: Increased risk of kidney and testicular cancer (PFOA specifically classified as a likely carcinogen)
  • Thyroid disease: PFAS can disrupt thyroid hormone function
  • Immune system effects: Reduced vaccine response and increased susceptibility to infections
  • Reproductive issues: Lower birth weights, preeclampsia, and reduced fertility
  • Liver damage: Elevated cholesterol and liver enzyme levels
  • Developmental effects in children: Potential impacts on growth, learning, and behavior

Current EPA Regulations

The EPA set enforceable Maximum Contaminant Levels (MCLs) for six PFAS compounds in April 2024:

| PFAS Compound | MCL | |---|---| | PFOA | 4 parts per trillion (ppt) | | PFOS | 4 ppt | | PFHxS | 10 ppt | | PFNA | 10 ppt | | HFPO-DA (GenX) | 10 ppt | | Mixture of 2+ PFAS | Hazard Index of 1 |

However, in May 2025, the EPA rolled back enforceable standards for 4 of these 6 compounds, creating regulatory uncertainty. Several states have established their own, often stricter, standards.

How to Remove PFAS From Your Water

The most effective home treatment methods for PFAS removal:

  1. Reverse Osmosis (RO): Removes up to 99% of PFAS. This is the gold standard for PFAS removal. Point-of-use RO systems installed under the kitchen sink typically cost $200-500.

  2. Activated Carbon Filters: Granular activated carbon (GAC) can remove 60-90% of longer-chain PFAS (like PFOA and PFOS) but is less effective for shorter-chain PFAS. Carbon block filters generally outperform granular carbon.

  3. Ion Exchange Resins: Specialized anion exchange resins can be highly effective for PFAS, though residential systems using this technology are less common.

Important: Standard pitcher filters and refrigerator filters provide minimal PFAS removal. If PFAS is a concern in your water, invest in an NSF-certified RO system.

How to Check Your Water for PFAS

  1. Check your city's water quality report on MyCleanWater — we include UCMR5 PFAS testing data for your water system
  2. Request your utility's Consumer Confidence Report (CCR) — utilities are required to publish these annually
  3. Get your water tested — mail-in lab tests from certified laboratories can test for specific PFAS compounds in your tap water

The Bottom Line

PFAS contamination is widespread — EPA data from the UCMR5 monitoring program has detected PFAS in water systems serving over 176 million Americans. While regulatory standards are in flux, the science on health effects is clear. If your water system has detected PFAS, a reverse osmosis filter is the most reliable way to protect your household.