PFAS 101

PFAS in Drinking Water & PFAS in Groundwater

As testing data of PFAS is collected, the context of what these PFAS sampling results represent and an overview of how levels of PFAS found in groundwater differ from PFAS found in drinking water are needed to better understand the data and what it means for human exposure.


Drinking Water and Groundwater image

Addressing PFAS under the Safe Drinking Water Act

Drinking water is regulated by the Safe Drinking Water Act to ensure that chemicals found in potable water are below levels that could pose a health risk to humans. Water used for drinking water is typically treated prior to being distributed to the public for consumption. It is the treated water that reaches the public through a tap as drinking water; it is tested frequently to ensure that water quality meets federal and state regulations. Details on DoD’s testing and actions for on-base drinking water can be found here.

Addressing PFAS under CERCLA

When DoD talks about cleaning up pollutants released into the environment under the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), it includes pollutants that are found in groundwater and surface water. Through the CERCLA process, DoD uses and includes all applicable and relevant regulations that protect human health and the environment for site conditions.

Groundwater:Groundwater can be a source for drinking water, but it is not typically potable water; that is, consumers are not drinking the groundwater directly without prior treatment by a public water system. For that reason, PFAS levels in groundwater are addressed under CERCLA with different requirements for cleanup. Each location where PFAS is found may have site specific conditions that will affect the time needed to complete each phase of the CERCLA process. Unless there is an immediate exposure threat to human health (that can be addressed at any point in the CERCLA process with an interim removal action), it often takes years to investigate if there was a release, determine the extent of the release, identify site conditions, and develop a cleanup strategy appropriate for that specific location. More information on DoD’s cleanup efforts can be found on our PFAS Data webpage.

Off-Base Drinking Water:Finally, there are cases where groundwater is being used as drinking water, most often found in private residential wells. DoD refers to these locations and this water as “off-base drinking water.” While EPA does not regulate private wells nor does it provide recommended criteria or standards for individual wells, DoD has identified locations where PFAS releases off-base have impacted drinking water and taken immediate action to provide residents alternate water. More information on these response actions can be found here.

In addition to the response actions that have been taken, DoD conducts sampling of drinking water off-base to ensure it identifies potential impacts of PFAS resulting from DoD activities. Final testing results for PFAS in off-base drinking water in an area in the United States located adjacent to and down gradient from a DoD military installation, FUDS, or National Guard facility are searchable by state here.

Q&As for PFAS in Groundwater vs PFAS in Drinking Water

Groundwater exists in underground aquifers and flows and migrates into the bedrock through the soil. Groundwater can exist at varying quantities and varying depths, from shallow levels of 1 foot below the surface to hundreds of feet deep. Depending on a number of factors, including the conditions of the soil, the amount of rainfall, nearby surface waters, drinking water wells, land use, etc. groundwater can migrate slowly or quickly (extending further distances).

Groundwater can be a source for drinking water, but unlike “drinking water,” it is not consumed directly. For that reason, people are not typically exposed to any pollutants that exist in the groundwater and the levels of pollutants are regulated differently than that in drinking water.

Yes. DoD has established policies for regular, periodic sampling of on-base drinking water to ensure safe drinking water for military, civilians, and their families. More information can be found here.

No. Groundwater is not consumed as drinking water at any military installation. It is tested at varying underground depths and not at the tap or faucet. Before drinking water reaches the tap, it undergoes treatment to ensure that the water quality meets EPA's standards for drinking water. DoD has tested all drinking water on military installations to ensure that it meets all federal and state water quality requirements. DoD has taken action at any location where on-base drinking water exceeded 70 parts per trillion (ppt) of PFOS and PFOA.

DoD also identified any groundwater used as a source of drinking water in private water wells. DoD has taken immediate action to provide alternative drinking water to those residents where PFAS levels exceeded 70ppt. Response actions from DoD have included providing bottle water, installing filtration systems for houses, and connecting houses to municipal water systems. The EPA does not regulate private wells nor does it provide recommended criteria or standards for individual wells.

DoD has investigated locations and concentrations where PFAS has migrated or been released off-base to determine necessary cleanup actions. DoD identified any groundwater used as a source of drinking water for private water wells and has taken immediate action to provide alternative drinking water to those residents where levels of PFOS and PFOA exceeded 70 parts per trillion (ppt). Response actions DoD has taken include providing bottled water, installing filtration systems for houses, and connecting houses to municipal water systems. The EPA does not regulate private wells nor does it provide recommended criteria or standards for individual wells.

DoD’s cleanup program is risk-based, resulting in a “worst first” approach. Testing results of PFAS in groundwater at a location may indicate high levels of PFAS, however it is only one factor when determining a site’s risk to human health and the environment. Other factors that could determine a site’s risk and proposed cleanup plan and schedule include the complexity of the site’s groundwater and geological conditions, the proximity to a drinking water source, the potential human exposure routes, and how quickly it is migrating.

DoD takes into account these considerations, evaluating relative risk and sequencing for cleanup using DoD’s Relative Risk Site Evaluation (RRSE) framework. The Department developed the RRSE framework in consultation with regulators and community stakeholders to provide a consistent approach to prioritize known or suspected releases of hazardous substances and pollutants or contaminants for cleanup.