Per- and polyfluoroalkyl substances (PFAS) represent unique challenges to private well owners. While public water supplies must be tested and treated to EPA standards prior to delivery to individual homes and businesses, private well water quality testing, like well maintenance, is entirely the responsibility of the well owner. To assist private well owners, VDH has always provided general guidance on water quality testing, and we developed this page specifically to provide guidance with regard to potential PFAS in wells.
In the sections below you will find answers to questions frequently asked by private well owners. A separate VDH page, "Per- and Polyfluoroalkyl Substances (PFAS)”, describes the sources of PFAS compounds, health effects, and VDH recommendations to reduce consumer exposure.
Per- and polyfluoroalkyl substances (PFAS) are a group of human-made chemicals that were created for a variety of household and industrial uses. PFAS can repel oil, grease, and water, so they have been used in protective coatings for many different products including food packaging, nonstick cookware, carpets and upholstery (stain-protectants), mattresses and clothing (water-proofing), and have also been used in fire-fighting foams. Some of the more commonly known PFAS are perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). GenX chemicals are considered a replacement for PFOA and PFBS is considered a replacement for PFOS.
While consumer products and food can be sources of exposure to PFAS, private drinking water can be a significant source of exposure at locations where these chemicals have contaminated water supplies. Such contamination is often localized and associated with a specific facility; for example, an airfield where PFAS were used for firefighting or a facility where these chemicals were produced or used.
Studies have shown that only a small amount of PFAS can get into your body through skin. Hence, neither bathing nor showering are likely to be primary routes of PFOA, PFOS, GenX chemicals, or PFBS exposure. While EPA’s MCLs are primarily focused on drinking water ingestion, not exposure through skin or breathing, they account for a margin of safety for other potential exposure routes, such as through skin (dermal), breathing (inhalation), diet, consumer products, etc.
No, these chemicals cannot be removed by heating or boiling water.
No. VDH does not have a program for the sampling and testing of water quality in private wells, nor the authority to require ongoing sampling and testing of private wells to be performed by others. Water quality testing of a private wells is solely at the discretion of the well owner.
VDH recommends that owners or users of private drinking water wells test the well water for PFAS contamination, especially if the well is located near a known source of PFAS or of other water supplies where PFAS has been detected. Sources of PFAS may include airfields where certain firefighting foams were used in the past, firefighting training areas, certain manufacturing facilities, and some waste disposal sites. Because PFAS have been widely used in consumer products, it is possible that some septic systems and landfills may also be a source of PFAS in groundwater.
VDH does not specify a distance from a documented PFAS release that represents a threat to a private well, because local conditions (geology, well depth, specifics of the documented release, etc.) is variable.
Finding a Laboratory
Use the Laboratories Approved by EPA to Support UCMR5 list to find laboratories that have been certified by EPA to test for PFAS in drinking water. Note: this list is subject to update and there may be other laboratories able to test for PFAS.
What Test Method Should I Use?
Currently, there are three U.S. EPA testing methodologies for testing drinking water for PFAS. Commercial laboratories will analyze drinking water for PFAS using either USEPA Method 537, 537.1, or 533. These methods test for multiple PFAS compounds. Talk to a laboratory representative to determine which method the lab recommends.
How to Collect a Water Sample
The first thing you will need to consider is whether you want to collect a sample of your well water before any treatment (such as a water softener) or after the treatment. This will determine the sample location you will collect water from. When collecting the water sample, VDH encourages well owners to avoid cross-contamination by carefully following the PFAS sample collection procedures or those provided by the laboratory that will be doing the analysis. Please note that, to avoid cross-contamination, sample collection containers are specific to the analysis being requested. The laboratory will provide you with the appropriate sample container(s). Do not simply fill an old peanut butter or pickle jar and submit it to the lab.
If the initial testing does not detect PFAS, VDH does not recommend additional testing unless one or more of the following conditions apply:
- A new release of PFAS is documented in the vicinity of your well intake, especially if your well is downhill or downstream of the source of release. VDH does not specify a distance from a documented PFAS release that represents a threat to a private well, because local conditions (geology, well depth, specifics of the documented release, etc.) is variable.
- Well owners in your area are advised by EPA, VDH, another state agency, or your local government to consider testing your well water.
EPA Drinking Water Standards
On March 14, 2023, EPA released information regarding proposed National Primary Drinking Water Regulation (NPDWR) to establish legally enforceable Maximum Contaminant Levels (MCLs) for six PFAS known to occur in drinking water. While these MCLs do not apply to private wells, MCLs are commonly used as a basis to understand private well water quality. Specifically:
EPA is proposing a NPDWR to establish legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water. PFOA and PFOS as individual contaminants, and PFHxS, PFNA, PFBS, and HFPO-DA (commonly referred to as GenX Chemicals) as a PFAS mixture. EPA is also proposing health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these six PFAS.
|Compound||Proposed MCLG||Proposed MCL (enforceable levels)|
|PFOA||Zero||4.0 parts per trillion (also expressed as ng/L)|
|HFPO-DA (commonly referred to as GenX Chemicals)|
For more information about EPA proposed enforceable drinking water standards see
CDC Minimal Risk Levels
The Center for Disease Control and Communication (CDC) Agency for Toxic Substances and Disease Registry developed the PFAS Exposure Assessment Technical Tools (PEATT) to help State, local, tribal, and territorial health departments conduct PFAS biomonitoring activities, with the assumption that drinking water is the primary source of PFAS exposure. The PEATT include a protocol for statistically-based representative sampling, risk communication materials, questionnaires, and EPA’s water sampling protocol to help characterize PFAS exposure in communities.
CDC Minimal Risk Levels (MRLs) are screening levels. CDC uses them to identify environmental exposures that might harm people’s health. If an exposure is below an MRL, it is not expected to result in adverse health effects. If an exposure is above an MRL, CDC conducts further evaluation to determine if the exposure might harm human health. CDC sets each MRL below a value that is likely to cause a health effect. CDC develops MRLs using data from the epidemiologic and toxicologic literature. When the scientific data on a hazardous substance is incomplete, CDC applies uncertainty factors as part of the MRL calculation. These uncertainty factors help ensure that MRLs are at a level where health effects in people are not expected by accounting for incomplete information about the chemical levels that may be associated with health effects, and other variables.
CDC - ATSDR (PEATT) MRLs.
|PFOA||78 ppt||21 ppt|
|PFOS||52 ppt||14 ppt|
|PFHxS||517 ppt||140 ppt|
|PFNA||78 ppt||21 ppt|
Which Standard Should I Use?
It is common for private well water quality to be evaluated by direct comparison to EPA MCLS. However, VDH has no enforcement authority to either require comparison to MCLs or dictate enforcement based on test results. Public water supplies must conduct water quality sampling on a regular basis, and compliance is generally based on running annual averages of the test results. This helps to account for potential high and low results which may not represent ongoing water quality. In contrast, private well owners typically rely on a single sample or "snapshot," which can make decision-making more of a challenge.
To afford opportunity for private well users to make informed decisions, VDH lists both the EPA MCLs and CDC's MRLs related to PFAS.
The difference between the EPA proposed MCLs and the CDC MRLs reflects both a distinction between public and private water supplies and the reality that knowledge about PFAS is rapidly changing. This can be confusing for well owners because EPA does not regulate private wells nor does it provide recommended criteria or standards for individual wells. Distinctions between EPA MCLs and CDC MRLs are also attributable, at least in part, to different toxicological studies referenced by the different agencies. VDH recognizes that both EPA and CDC developed these standards based on best available current science. Further, both the EPA MCLs and the CDC MRLs apply to the risk of lifetime exposure as opposed to direct immediate threat.
The Laboratory Certificate-of-Analysis
The certificate of analysis is the report issued by the laboratory summarizing test results. PFAS results are generally listed as "parts per trillion" or PPT, This is notated as ng/L which means nanograms per liter. This is a very small number, akin to 1 ounce of water in over 1136 Olympic sized swimming pools.
It is possible that the laboratory might report results as µg/L (micrograms per liter or parts per billion). If so, move the decimal point three units to the right to convert to ng/L. For example 1 µg/L is the same as 1000 ng/L.
What do these numbers mean?
EPA has proposed MCLs for six PFAS (PFOS, PFOA, GenX chemicals, PFNA, PFBS, and PFHxS). The concentration of PFOS and PFOA can be compared to the proposed MCLs directly. The other four PFAS are evaluated together against a Hazard Index. Open "Understanding the EPA's Hazard Index for private well water samples" in the next section for a tool allowing you to determine the Hazard Index.
What about all these other chemicals?
You may find several dozen PFAS listed on the certificate-of-analysis and wonder why they are there. EPA Method 533 for example, tests for 25 PFAS. The EPA proposed MCLs include only six PFAS, so what should you do if one or more of the other PFAS are detected? At present, none of the other PFAS are regulated and there is no standard to compare them to. New information regarding PFAS becomes available as agencies including EPA and the CDC conduct ongoing research, so it is advisable that you keep a copy of your certificate-of-analysis in your permanent records.
Use the Be Well Informed Virginia Tool
Be Well Informed Virginia is a joint project between VDH and the Virginia Household Water Quality Program. It allows you to enter water quality data from your well test and obtain a detailed evaluation of your well water quality accompanied by information about appropriate response options. The information provided by BE WELL INFORMED VIRGINIA is for informational purposes and does not take place of direct consultation with medical, water treatment, or well inspection professionals. There may be other conditions related to your private well or home plumbing not addressed by this online tool which could be factors related to determination of water treatment or other response to your water test results.
The Be Well Informed Virginia current configuration allows for the entry of PFOS and PFOA data.
Use this LINK to use Be Well Informed Virginia.
It is certainly understandable that private well owners might be confused by the EPA designation of a "Hazard Index" for four distinct PFAS (PFHxS, GenX chemicals, PFNA, and PFBS). The Hazard Index is a number calculated from the concentrations of the four PFAS, and it is a simple number with no units (such as "parts per trillion)." The Hazard Index is a long-established tool that EPA regularly uses to evaluate risks of chemical mixtures. It is, for example, used at contaminated Superfund sites.
EPA is following recent peer-reviewed science that indicates that mixtures of PFAS can pose a health risk greater than each chemical on its own. This Hazard Index helps to account for the increased risk from mixtures of PFAS that may be found in contaminated drinking water. It considers the different toxicities both singularly and in combition. In the simplest possible terms, it addresses the fact that adverse impacts from certain substances in combination may be more severe than from the individual impacts of each.
Your laboratory certificate-of-analysis might have taken the test results for PFHxS, GenX Chemicals, PFNA, and PFBS and determined the Hazard Index for you. If not, you can enter your data in this calculator to determine the hazard index for your well water sample.
If the Hazard Index is greater than "1" (no units), the proposed EPA MCL is exceeded. This applies to any combination of the four PFAs. It is possible to exceed the proposed Hazard Index MCL when only one, two, or three of the PFAS are present. Moreover, a high concentration of one Hazard Index PFAS could drive an MCL exceedance.
VDH does not advocate bottled water based solely on concentrations of these chemicals in drinking water that exceed the MCLs. The U.S. Food and Drug Administration (FDA) has not established standards for PFOA, PFOS, GenX chemicals, or PFBS in bottled water at this time. If you have questions about bottled water, please contact the FDA.
We know that the lower the levels of PFOA and PFOS, the lower the risk. You can consider taking actions to reduce levels in their drinking water by installing treatment technologies or obtaining an alternative-source of drinking water that has been tested and confirmed to not be contaminated by these PFAS, if available.
Individuals who are concerned about PFOA, PFOS, GenX chemicals, or PFBS in their wells or in their homes may consider in-home water treatment filters that are certified to lower the levels in water. Learn more about these filters. If you are concerned about potential health effects from exposure to PFOA, PFOS, GenX chemicals, or PFBS above the health advisory level, contact your doctor or health care professional.
Point of Use (POU) water treatment devices treat the water at one fixture in a home, such as a kitchen faucet or ice maker. Point of Entry (POE) water treatment devices treat all of the water for the main water line serving a whole house.
Yes, you may use a POU or POE treatment device to remove PFAS. However, before installing any treatment device for drinking water, you should get your water tested, because the type of treatment device you select will depend on the level of specific PFAS in the water. You should also test your water after the treatment device is installed to verify that it is removing PFAS to desired levels.
Ingestion of water with elevated PFAS is the main health concern, rather than other uses such as showering or use of the water for laundry. Therefore, installing a POU treatment device for drinking or food preparation in the kitchen, e.g., under a kitchen sink, may be a good option and location for a treatment device.
Although POU and POE treatment devices may not yet be specifically certified to meet EPA proposed MCLs for PFAS, there are systems that have been designed to reduce the sum of PFOS and PFOA to below EPA’s former Health Advisory of 70 ng/L. Any treatment device you use should be certified to meet the National Sanitation Foundation (NSF) standards to remove PFOS and PFOA compounds. Please be aware that the NSF certification process takes some time, and you therefore may not find a treatment device certified to the current proposed MCLs. Such treatment devices nevertheless will provide protection, and can always be upgraded in the future. If you choose to install a treatment device, to verify that the device is removing PFAS from your well water, you may need to resample your water after the treatment device has been installed.
Critically, home treatment devices are not "set and forget" in nature. There will be periodic maintenance (for example, filter replacement) necessary to ensure the treatment remains effective.
PFAS are a topic of current research by public health agencies. You can get more information at the following pages: