- PFAS are a large family of manmade chemicals that break down extremely slowly in the environment.
- Firefighting foam used at former military bases near Horsham and Warminster is a major local source.
- You cannot see, smell, or taste PFAS. A certified lab test is the only way to know your level.
- Under-sink reverse osmosis is one of the most effective home treatments. Boiling does not help.
Few water topics generate as many questions in Southeastern Pennsylvania as PFAS. Our region has been at the center of the national conversation for years, starting with contamination around former military bases in Bucks and Montgomery counties. Since then, testing has turned up PFAS in public systems and private wells across a much wider area.
This guide covers what PFAS are, why they are here, what the rules say, and what you can actually do about them at home.
What PFAS are
PFAS stands for per and polyfluoroalkyl substances. It is a family of thousands of manmade chemicals that share an extremely strong carbon and fluorine bond. That bond is what makes them so useful, since it repels water, grease, and stains and holds up to heat. It is also why they barely break down in the environment, which earned them the nickname forever chemicals.
Since the 1940s, PFAS have been used in nonstick cookware, stain-resistant carpet and fabric, waterproof clothing, food packaging, and certain firefighting foams. The two most studied are PFOA and PFOS. Manufacturers in the United States have largely phased those two out, but they persist in soil and groundwater, and many newer PFAS remain in use.
Why health agencies are concerned
PFAS accumulate in the body over time. Research has linked exposure to certain PFAS with effects that include changes in cholesterol, reduced vaccine response in children, effects on growth and development, and increased risk of some cancers. The science is still developing, and risk depends on the specific chemical, the level, and the length of exposure.
Drinking water is one of the main ways people are exposed, which is why it gets so much regulatory attention. It is also one of the easiest exposures to reduce.
How PFAS got into our water
The biggest local story involves aqueous film forming foam, a firefighting foam that was used for decades at military installations. Foam used at the former Naval Air Station Joint Reserve Base Willow Grove in Horsham and the former Naval Air Warfare Center in Warminster soaked into the ground and reached the aquifers that supply nearby public systems and private wells.
Communities including Horsham, Warminster, and Warrington were among the first in the country to take wells offline and add treatment. Since then, broader testing has found PFAS in many public systems across Bucks, Montgomery, and Chester counties, from a range of sources that include industrial sites, landfills, and wastewater.
What the limits are today
PFAS rules have changed quickly and are still evolving, so treat the figures below as a snapshot and check the latest guidance from the EPA and the Pennsylvania DEP.
- In 2023, Pennsylvania adopted its own drinking water limits for public systems of 14 parts per trillion for PFOA and 18 parts per trillion for PFOS.
- In 2024, the EPA finalized national limits of 4 parts per trillion each for PFOA and PFOS. Compliance deadlines and the treatment of other PFAS in that rule have since been revised, and further changes are possible.
- None of these limits apply to private wells. They are still the most useful benchmark for deciding whether your well water needs treatment.
A part per trillion is a tiny amount, roughly one drop in a string of rail tank cars miles long. That is why PFAS testing has to be done by a lab with specialized equipment, and why home test strips cannot measure it.
How to find out if PFAS are in your water
If you are on public water
Your water supplier publishes an annual water quality report, often called a Consumer Confidence Report. Many suppliers in our region now list PFAS results and any treatment they have installed. Look up your supplier’s most recent report, or call and ask directly.
Keep in mind that a system wide average can differ from what comes out of your tap, especially if your supplier blends water from several wells. A tap test tells you exactly what you are drinking.
If you are on a private well
A laboratory test is the only way to know. Choose a lab accredited for PFAS analysis, and ask which method it uses. EPA Methods 533 and 537.1 are the standard approaches for drinking water. PFAS sampling has stricter rules than most tests, since common household items can contain PFAS and contaminate the sample.
Treatment options compared
Not every filter that claims to reduce contaminants works on PFAS, and performance varies widely between products. Here is how the main options compare.
| Treatment | How well it handles PFAS | Where it goes | Things to know |
|---|---|---|---|
| Reverse osmosis | Very effective, typically removing 90% or more | Kitchen sink | Treats drinking and cooking water. Look for NSF/ANSI 58 certification that lists PFOA and PFOS. |
| Granular activated carbon | Effective when properly sized and maintained | Whole-home or under-sink | Carbon fills up over time and must be replaced on schedule to keep working. |
| Ion exchange resin designed for PFAS | Effective | Usually whole-home | Specialized media. Not the same as a standard water softener resin. |
| Pitcher and faucet filters | Varies widely | Countertop | Only some are certified for PFAS. Check the certification, not the box claims. |
| Boiling | Does not work | Stove | Boiling concentrates PFAS as water evaporates. |
For most households, the practical answer is reverse osmosis at the kitchen sink. Drinking and cooking are where nearly all PFAS exposure from water happens, and reverse osmosis handles both reliably. It also reduces lead, arsenic, nitrate, and many other contaminants at the same time.
Whole-home treatment makes sense when levels are high, when you want protection at every tap, or when a lender or buyer requires it. A whole-home system sized for PFAS usually involves dedicated carbon or specialized resin and a regular media replacement schedule.
Keeping treatment working
- Change reverse osmosis prefilters and membranes on the schedule the manufacturer recommends.
- Replace carbon media before it is exhausted, not after. Exhausted carbon can release what it captured.
- Retest after installation to confirm the system is doing its job, then periodically after that.
- Keep records of every test and every filter change.
Common questions
Is it safe to shower in water with PFAS?
Current research suggests skin contact and inhalation during showering are minor exposure routes compared with drinking water. That is why most guidance focuses on drinking and cooking water first.
Does my water softener remove PFAS?
A standard softener is designed to remove hardness minerals, not PFAS. Some whole-home systems pair softening with carbon, and carbon can reduce PFAS, but the amount depends on the carbon volume and how recently it was replaced. If PFAS is your concern, test before and after to see what your system is actually doing.
Should I switch to bottled water?
Bottled water can be a reasonable short-term step while you test and decide on treatment. Over the long run, a certified reverse osmosis system is usually more convenient, produces less waste, and costs less.
The bottom line
PFAS are a real issue in Southeastern Pennsylvania, but they are also one of the more manageable ones at home. Find out your level with a certified test. If treatment makes sense, reverse osmosis at the kitchen sink handles the water you actually drink. And if your levels are low or not detected, you can stop worrying and spend your money elsewhere.