Per- and polyfluoroalkyl substances, also known as PFAS, are a group of over 5,000 human made compounds. Used since the 1940s, PFAS compounds can be in a wide range of consumer and industrial products and processes. PFAS released to the air, soils, ground- or surface water can enter into nearby drinking water sources. To assess the presence of PFAS in state drinking water sources, the Maryland Department of the Environment (MDE) has initiated an assessment from 137 selected Community Water Systems.

These Community Water Systems were selected by the proximity, number, and type of potential sources of PFAS MDE mapped over 2,000 potential sources of PFAS in Maryland. The 2,000 potential sources include military installations, fire training areas, airports, landfills, manufacturing facilities, and wastewater treatment plants.

The purpose of this initial sampling effort is to assess the occurrence of PFAS in Maryland’s most vulnerable public drinking water sources and, when necessary, to take action to require monitoring or risk mitigation measures.

In Poolesville’s water system, elevated levels of PFOA or PFOS were detected in the water samples collected from Well 2 and Well 3. A Tier 2 Public Health Advisory Notice was mailed to every resident. While there are no national or state Maximum Contaminant Levels (MCLs) for PFAS in drinking water, the EPA released interim health advisories for PFOA and PFOS. For this reason, we have taken Wells 2 and 3 offline.

Since the Health Advisory was issued, the Town has been working with MDE and has developed a pilot program for removing these contaminants from the drinking water. Carbon activated charcoal filtration units have been installed at Well 3 and smaller bench top corn-based filtration units are being tested on both Wells 2 and 3. Once sufficient analysis is gathered, the MDE will allow Well 3 to be brought back online. A determination of the two types of media will be made to compare removal rates, cost and ongoing maintenance. Once this step is complete, the Town will look to broaden the treatment of other wells as needed. Grants have been applied for to help offset the costs.

Early May 2023, the Town received EPA results from PFAS sampling that occurred 2/7/2023. As detailed below, one or more per- and polyfluoroalkyl substances (PFAS) from sampling at several Poolesville wells were reported above the U.S. EPA lifetime health advisory (HA) level in preliminary results (i.e., laboratory-approved but not yet reviewed by EPA). 

EPA has changed the previous HA values to values that are lower than laboratory analytics can currently test for. As you will see in the tables below, the HA interim values for PFOA and PFOS are .004 ppt and .02 ppt respectively while the minimum reporting levels (MRL) are 4 ppt. (PPT = Parts per Trillion)

Additional Resources

Meaningful and Achievable Steps You Can Take to Reduce Your Risk

Town of Poolesville PFAS Lab Report 

PFA Presentation from Scientist Kathleen Mihm to the Town Commissioners