Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) are a large group of chemicals used since the 1940s in common household and commercial products. PFAS have unique chemical properties and are often used to keep food from sticking to cookware. They also make clothes, carpets, and furniture resistant to water and stains.

Many recent news articles and movies focus on PFAS, typically when they are found in local drinking water. Water gets this media attention because it is regularly tested for potentially harmful chemicals by law, unlike many of the other things we eat, drink, and breathe.

PFAS are slow to break down in the environment and can move far from their original use areas. The manufacturing and use of these products puts PFAS into the environment, where, over time, they may end up in drinking water supplies. Understanding how PFAS can enter our environment, our homes, and our bodies can help us manage our exposure.

  • PFAS can enter the environment as we throw away products that have PFAS, and through our own bodily waste.
  • PFAS can also enter the environment when companies make products with PFAS, releasing it directly into our water and air.
  • Natural breakdown of PFAS is negligible or sometimes non-existent, allowing PFAS to build up and remain in the environment. This leads to increasing levels of PFAS in the natural resources we use from the environment, like water, food, and soil.

Because they are used in so many everyday products, most people in the United States and other industrialized countries now have PFAS in their blood. Exposure to PFAS depends on many things, PFAS-images-wastestreamsincluding the amount of PFAS in your local environment, the amount of PFAS in various food, water, or other products, and how much a person eats, drinks, or uses those products.

  • We swallow, inhale, or rub PFAS into our skin by using certain products, eating or drinking impacted food and water, and breathing in the dust in our homes.
  • As in the environment, PFAS can build up in the human body over time. They have been associated with some negative health effects.

PFAS-cycles-infographicScientists are still studying the health effects of elevated PFAS blood levels, which may include certain types of cancer, high cholesterol, or decreased vaccine response in children. Blood tests can tell us how much PFAS we may have in our blood compared to population averages. But blood testing is not prognostic (suggestive of a future health effect) or diagnostic (linked to a current health effect). As scientists complete more studies, more information will be available on the health effects of high PFAS blood levels, and regulations related to PFAS will continue to change.

Look to official sources of information to stay up to date on the latest news. Reliable sources include:

Your health and the health of your household are our first priority. That’s why we look for potentially concerning contaminants like PFAS long before they are regulated. Water quality is regulated to protect public health and drinking water quality is public information. Because of this, water often provides our first clues about trends we need to pay attention to.

Water also connects all of us. Vast as it may seem, our world is a closed system. There is no such thing as “new” water. All water is shared and flows in and out of streams, rivers, oceans, and each of us. Along the way, it often carries what we put in it, including chemicals like PFAS.

Water utilities are responsible for maintaining water quality according to regulations while also keeping drinking water affordable. Treatment to remove PFAS from water can happen at utilities and in our homes – using technologies like activated carbon and reverse osmosis – but treatment can be expensive. Our country’s regulatory process helps make sure we are delivering the safest water at a cost affordable to all. Together with many partners, we take steps to protect our source waters from emerging contaminants, and we test and treat your drinking water to the standards set by the U.S. EPA and the Pennsylvania Department of Environmental Protection. 

Each year we provide our Annual Drinking Water Quality Report to the public. This report is the best place to find reliable information about relevant regulations and your local drinking water quality.

PFAS-images-environment-cyclePFAS can enter the environment as we throw away products that have PFAS, and through our own bodily waste. Natural breakdown of PFAS is negligible or sometimes non-existent, allowing PFAS to build up and remain in the environment. This leads to increasing levels of PFAS in the natural resources we use from the environment, like drinking water, food, and soil.

PFAS exposure can vary depending on your local environment, but you can take steps to reduce the PFAS around you. Choosing products that do not have PFAS can require some research, but it is an effective way to reduce your exposure. It can also mean giving up some product features such as “non-stick,” or “water- or stain-resistant.” Consider replacing older and worn-out products with these features.
  • PFAS-images-nonstick-iconAvoid buying non-stick cookware and stain-resistant furniture and carpeting containing PFAS. Look for 'fluoro' or 'perfluoro' in a list of ingredients or ask the manufacturer. You may also find this summary of PFAS product information and certification resources useful.
  • Limit eating foods packed in materials that use PFAS. Common food packaging that may have PFAS includes microwave popcorn bags, fast food boxes (like french-fry containers and pizza boxes), and bakery bags.
  • Minimize the dust in your home to limit PFAS particles in the air. Change your home’s air filter on a regular basis and leave your shoes at the door to avoid tracking in dirt and pollutants.
  • PFAS-images-personalcare-iconAvoid personal care products that contain PFAS. These include certain types of dental floss, nail polish, facial moisturizers, and cosmetics.
  • Learn about the PFAS levels in your local drinking water. If you want an at-home treatment option, look at the NSF International list of products certified to remove PFAS from drinking water in the home.
  • PFASCentral.org maintains a list of manufacturers and retailers that have taken steps to remove PFAS chemicals from their products.

What is the Borough Doing About PFAS?

The Borough of Carlisle operates the Carlisle Water Treatment Plant, which treats water from the Conodoguinet Creek and provides drinking water to approximatelyWater Treatment Plant 27,000 people in Carlisle and the surrounding area. The plant uses several treatment steps to remove contaminants and help ensure the water meets drinking water standards.

In April 2024, the U.S. Environmental Protection Agency (EPA) established new, stricter drinking water standards for several PFAS compounds. Public water systems must meet these federal standards by 2029.

Testing of Carlisle’s source water and treated drinking water found PFAS, including PFOA and PFOS. The highest concentrations reported during the testing were 7.1 parts per trillion (ppt) for PFOA and 15.8 ppt for PFOS. Both exceed the EPA’s federal limit of 4 ppt for each compound.

Although the Borough’s water meets Pennsylvania’s existing drinking water requirements, the new federal standards require additional treatment to reduce PFAS levels. The Borough’s goal is to reduce PFAS in treated drinking water to levels that cannot be detected by the testing methods used.


Testing Treatment Options
Before selecting a treatment system, the Borough worked with its engineering consultant to evaluate different technologies. Two options were tested: ion-exchange (IX) resin and granular activated carbon (GAC). Both are used to remove contaminants from water.

The Borough authorized pilot testing in December 2023. The study took place from January through October 2025 and evaluated how well each treatment method removed PFAS under the plant’s operating conditions.PFAS Testing Setup at Water Plany

The results showed that both methods reduced PFAS concentrations to undetectable levels during the pilot study. However, the ion-exchange resin experienced biological buildup during warmer months, which affected its performance and could lead to more frequent maintenance and media replacement.

Granular activated carbon consistently reduced PFAS to undetectable levels without the same seasonal performance issues. Based on these results, the Borough selected GAC as the preferred treatment method.


What Improvements are Planned?

The proposed project will add a dedicated PFAS treatment system at the existing water treatment plant. Planned improvements include:

  • Granular activated carbon filtration: New filtration units designed to remove PFAS from the water supply.
  • Pumping system upgrades: Improvements to help move water through the new treatment equipment.
  • Backwash system: Equipment to clean the filters as part of ongoing plant operations.
  • Chemical feed system modifications: Changes to existing equipment to accommodate the new treatment process.
  • Sludge tank improvements: Upgrades to support the new system’s initial filling and backwashing operations and improve safety during the transportation of residuals.'
The project will also require additional engineering work, environmental reviews, and permits before construction can begin.

 


What's Next?

The EPA’s new PFAS standards establish a 2029 compliance deadline for public water systems. The Borough is moving forward with plans to install the new treatment system and meet that deadline.

In August 2026, Borough Council approved a contract for final design and permitting services for the PFAS treatment system. This phase will advance the engineering plans, identify necessary environmental approvals, and prepare the project for construction.

The Borough will continue working with its engineering consultant and state regulators as the project progresses. These improvements are intended to reduce PFAS in Carlisle’s drinking water and help ensure the Borough continues to provide safe, high-quality drinking water to the community.

Updates will be shared as the project moves forward.