Per- and Polyfluoroalkyl Substances

PFAS: What are they?

PFAS are a group of man-made chemicals that were developed in the 1940s to be fire, oil, grease, water and stain resistant. The chemicals are found in a wide array of consumer and industrial products, including non-stick cookware, stain repellant, dental floss, cleaning products and cosmetics. According to the Centers for Disease Control and Prevention, the potential for health effects from PFAS in humans is not well understood. For more information about PFAS, check out the U.S. Environmental Protection Agency (EPA) site:

According to the Centers for Disease Control and Prevention the potential for health effects from PFAS in humans is not well understood. The EPA does not regulate PFAS compounds but maintains a health advisory of 70 parts per trillion (ppt) for two of the most common compounds, PFOA and PFOS. Currently, this is the only Federal health standard. One part per trillion is equivalent to one drop of water in 20 Olympic-sized swimming pools. Some states independently regulate, or propose to regulate, more PFAS compounds using more stringent standards. This is because of higher levels of PFAS found in their drinking water, and the presence of contaminated sites in their drinking water sources.

How do these compounds get in the environment?

Some of the most common means of PFAS entering the environment are discharges from PFAS manufacturing and processing facilities, and from facilities that use the product in large quantities, such as airports and military installations. Two of the most common compounds, PFOA and PFOS, have been the most extensively produced chemicals and are very persistent in the human body and environment – meaning they accumulate over time and don’t break down. Once discharged into the environment and into source water, PFAS compounds cannot be removed during the water treatment process. Fortunately, there are no known PFAS-contaminated sites located upstream of WSSC Water drinking water sources. In Maryland, the number of contaminated sites are very small and none of them are upstream of our drinking water source. Maryland Department of the Environment is currently assessing potential sources of PFAS contamination to inform management of future risks.

Is WSSC Water Safe?

Yes! Public health and safety of our customers is our top priority at WSSC Water. For more than 101 years, our water has consistently met all strict federal Safe Drinking Water Act requirements. In fact, we have never had a single drinking water quality violation in our history.

While there are currently no federal or state regulations mandating the monitoring or treatment of PFAS, WSSC Water conducted extensive water quality testing for six PFAS compounds, from July 2013 through April 2014 and again from March 2015 through October 2017, and found results below the U.S. Environmental Protection Agency’s (EPA) detection limits in its drinking water. Please see test results to the right.

WSSC Water Actions

  • Throughout its more than 101-year history, WSSC Water has always taken a proactive leadership position in protecting our drinking water supplies and testing for contaminants of emerging concern. 
  • On January 24, 2020, WSSC Water announced it will resume testing its water for the presence of PFAS substances at its Potomac and Patuxent Water Filtration Plants.
  • These two plants provide drinking water to 1.8 million residents in Montgomery and Prince George’s counties.
  • WSSC Water will test quarterly for 18 different PFAS compounds using new analytical method developed and approved by EPA.
  • This proactive measure goes above and beyond federal and state requirements.
  • Test results will be posted on this page.
  • In making the announcement to resume testing, WSSC Water General Manager and CEO Carla A. Reid strongly encouraged continued federal and state action to protect drinking water supplies.
  • WSSC Water has an aggressive water quality testing program – performing 500,000 laboratory tests per year on samples collected at both water filtration plants and 90 different locations throughout its service area.
  • WSSC Water will continue to closely monitor the national discussion on the need for possible federal PFAS testing and stands ready to implement additional robust testing measure should the EPA require water utilities to test for the presence of these compounds.
  • If customers have additional questions about water quality, call 301-206-4002.
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