Understanding PFAS

WSSC Water Prepared to Meet New Drinking Water Regulation on Forever Chemicals

Per- and polyfluoroalkyl substances (PFAS) are a large family of human-made chemicals used since the 1940s to make products resistant to heat, oil, stains and water. Because they don’t break down easily, PFAS are often called “forever chemicals.”

PFAS can be found in many products including: 

• Nonstick cookware
• Water-resistant clothing
• Food packaging
• Cleaning products
• Firefighting foams

When these materials are manufactured, used or disposed of, small amounts of PFAS can enter the air, soil and water, eventually reaching rivers and reservoirs that supply drinking water.

U.S. Environmental Protection Agency (EPA) PFAS Drinking Water Standards

In 2024, EPA finalized the first national drinking water standards for PFAS. The new rule sets legally enforceable levels, called maximum contaminant levels (MCLs), for six key compounds:

• Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS): Four parts per trillion (ppt) each
• Perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and hexafluoropropylene oxide dimer acid (HFPO-DA; also called GenX): 10 ppt each 

To put this into perspective, four ppt is equivalent to one drop of water in five Olympic-sized swimming pools.

Additionally, EPA finalized a Hazard Index that creates an enforceable drinking water standard for any mixture of two or more of the following four PFAS compounds: PFNA, PFHxS, PFBS and HFPO-DA (GenX).

The final rule requires public water systems, such as WSSC Water, to complete initial monitoring by 2027 and comply with the new MCLs by 2029.

WSSC Water’s Commitment

WSSC Water is committed to providing Prince George’s and Montgomery counties with excellent quality drinking water. We want our 1.9 million customers to know that they can trust their taps because our drinking water meets the final standards.

As an organization dedicated to protecting public health, we are committed to doing everything in our power to ensure our 107-year track record of water quality excellence continues.

Ongoing PFAS Monitoring

WSSC Water has been monitoring for PFAS proactively since 2020. We collect and analyze compliance samples quarterly and calculate a running annual average. The following tables display WSSC Water’s compliance testing results for our two water filtration plants, Patuxent and Potomac.

Patuxent Water Filtration Plant

Annual average as of July 2025

Potomac Water Filtration Plant

Annual average as of July 2025

Quarterly PFAS Test Results in detail

Frequently Asked Questions

PFAS: What are they?

PFAS, often referred to as "forever chemicals," are a group of thousands of human-made compounds that have been in use since the 1940s in common household and commercial products.  

They are resistant to heat, stains and water, making them popular additions to cookware, clothing, carpets, cosmetics and furniture. PFAS are also found in millions of other goods, including products you may have never imagined like dental floss, cake mix, cardboard straws and toilet paper. EPA estimates that 80% of a person’s exposure is from consumer products.  

PFAS not only enters the environment through consumer use and disposal but also through surface and groundwater contamination. For example, PFAS proved to be an essential addition to firefighting foam. Unfortunately, for many communities near airbases and airports, the washing down of the foam after training exercises led to surface and groundwater contamination.

PFAS: How do these human-made compounds end up in drinking water?

Our water filtration plants do not produce or use PFAS. However, PFAS can end up in source water and then drinking water due to continued manufacturing and use of PFAS-laden products.

For example, PFAS are still used with nonstick cookware. Scraping and washing a nonstick pan with PFAS discharges the compounds into our wastewater system.

Because of their resistant properties, PFAS can move through the conventional water treatment processes largely intact.

PFAS: What is WSSC Water doing to supply safe, clean drinking water to customers?

WSSC Water’s mission is to protect public health and safety by supplying safe, clean and reliable water to our 1.9 million customers. We are proud of our 107-year history of zero drinking water quality violations and remain committed to continuing this exceptional level of excellence.  

For several years, WSSC Water has been proactively testing for PFAS compounds in our drinking water, testing that went above and beyond federal and state requirements. WSSC Water monitors for 29 PFAS compounds that are included under EPA’s Fifth Unregulated Contaminant Monitoring Rule, also known as UCMR5. We will continue to transparently post our results as we conduct our tests.  PFAS Test Results

UMCR 5 testing is intended to give EPA and water providers a greater understanding of how pervasive PFAS are in our nation’s drinking water. WSSC Water will review our UCMR5 test results to determine if additional courses of action are necessary.  

PFAS: How to limit PFAS exposure?

Avoid buying nonstick cookware and stain-resistant furniture and carpeting containing PFAS. Look for ‘fluoro’ or ‘perfluoro’ in a list of ingredients or ask the manufacturer.  

Limit eating foods packed in materials that use PFAS, like microwave popcorn bags, fast food boxes and bakery bags.  

And avoid personal care products with PFAS, including certain dental floss, nail polish, facial moisturizers and cosmetics. Limiting the use of products containing PFAS will help protect drinking water supplies.  

Related Links

• Maryland and PFAS
• PFAS-Free Products
• Environmental Protection Agency

WSSC Water is committed to providing you with safe, clean drinking water. Should you have any water quality concerns, please let us know by visiting our Report a Water Quality Complaint page.

In the News

• Most local water utilities already meet new EPA limits on 'forever chemicals' (WJLA)
• How will new federal limits on ‘forever chemicals’ in drinking water affect DC area? (WTOP)

May 2023 - Excerpt from WSSC Water Letter to EPA

"... we strongly urge EPA to consider altering its regulatory approach to regulate PFAS at the source, placing the burden of proof that the products are safe for consumers and the environment on those who manufacture and utilize PFAS products before they are manufactured."

Read full letter