PFAS (“forever chemicals”)
National occurrence
3,539
Public water systems with a detection
1,717
Systems above an EPA PFAS limit
1,700
Highest single reading (ppt)
From EPA’s UCMR5 nationwide monitoring (2023–25). “Above limit” counts systems where a regulated PFAS exceeded its EPA maximum.
Most-affected systems
- NASHVILLE, TOWN OF NASHVILLE, NC 122.5× limit 15
- RUNNING SPRINGS WATER DISTRICT RUNNING SPRINGS, CA 59.1× limit 1
- COLLEGEVILLE TRAPPE JOINT PWD TRAPPE, PA 58.8× limit 34
- LUBECK PSD WASHINGTON, WV 44.9× limit 62
- ARTONDALE Tacoma, WA 38.4× limit 12
- EMMAUS BOROUGH PUBLIC WATER EMMAUS, PA 38.3× limit 1
- GWA NORTHERN WATER SYSTEM MANGILAO, GU 33.8× limit 40
- NEW MARTINSVILLE NEW MARTINSVILLE, WV 30.4× limit 55
Health & what it is
PFAS are a large family of synthetic chemicals used since the 1940s in non-stick, stain-resistant, and firefighting products. They are called “forever chemicals” because they break down extremely slowly and build up in the body and the environment over time.
According to the EPA and the federal ATSDR, exposure to certain PFAS above EPA’s limits over many years has been associated with effects including increased cholesterol, changes in liver enzymes, effects on the immune system, thyroid and developmental effects, and increased risk of kidney and testicular cancer.
In April 2024 the EPA finalized its first national drinking-water limits: 4 parts per trillion (ppt) for PFOA and for PFOS, and 10 ppt for PFHxS, PFNA, and GenX (HFPO-DA), with public water systems required to monitor and reduce levels.
Where it comes from
Manufacturing, firefighting foam (AFFF) at airports and military bases, and consumer products that leach into groundwater and surface water.
How to reduce PFAS at home
Look for a filter certified to NSF/ANSI 53, 58, or P473 — Reverse osmosis or activated-carbon block. RO and certified carbon are the most effective PFAS barriers.
- ✓Reverse osmosis (most effective for the broad PFAS family)
- ✓Activated carbon filters certified to NSF/ANSI P473 for PFOA/PFOS
- ✓Anion-exchange resin systems
Frequently asked questions
What is PFAS? +
Per- and polyfluoroalkyl substances. EPA set the first enforceable national limits in 2024. Manufacturing, firefighting foam (AFFF) at airports and military bases, and consumer products that leach into groundwater and surface water.
What is the EPA limit for PFAS in drinking water? +
The EPA limit is 4 ppt (PFOA & PFOS). To remove it, look for a filter certified to NSF/ANSI 53, 58, or P473.
What are the health effects of PFAS? +
PFAS are a large family of synthetic chemicals used since the 1940s in non-stick, stain-resistant, and firefighting products. They are called “forever chemicals” because they break down extremely slowly and build up in the body and the environment over time. According to the EPA and the federal ATSDR, exposure to certain PFAS above EPA’s limits over many years has been associated with effects including increased cholesterol, changes in liver enzymes, effects on the immune system, thyroid and developmental effects, and increased risk of kidney and testicular cancer. In April 2024 the EPA finalized its first national drinking-water limits: 4 parts per trillion (ppt) for PFOA and for PFOS, and 10 ppt for PFHxS, PFNA, and GenX (HFPO-DA), with public water systems required to monitor and reduce levels.
How do you remove PFAS from drinking water? +
Reverse osmosis (most effective for the broad PFAS family) Activated carbon filters certified to NSF/ANSI P473 for PFOA/PFOS Anion-exchange resin systems
Is PFAS in your water?
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