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Per- and polyfluoroalkyl Substances (PFAS)

Q: What are these chemicals and where do they come from?

A: Per- and polyfluoroalkyl substances (PFAS) are a family of over 5,000 man-made chemicals with many useful properties including the ability to repel water, prevent staining and increase heat resistance. PFAS have many industrial and consumer uses including the coating of fabrics, carpets, electrical wire, and non-stick cookware, in food packaging (e.g., microwave popcorn bags and fast-food wrappers), as a mist suppressant in metal plating, and in firefighting foam used by firefighters to put out petroleum fires, but not typically in home fire extinguishers. Four of the most studied PFAS, perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS), are found with the highest frequencies and concentrations in the environment, in humans and in wildlife. We know the most about the harmful effects and environmental fate of these four PFAS. While PFOS and PFOA have been phased out of production, they are very persistent chemicals and can remain in the environment for long periods after being removed from the marketplace.
    Q:  What is the current Connecticut DPH drinking water Action Level for PFAS and how was it developed?

A:  The CT DPH has derived individual health-based drinking water Action Levels (ALs) for four of the most widely studied PFAS that have also been detected in human blood more frequently and at much higher concentrations than other PFAS. These four compounds were included in our previous AL, “sum of CT 5” less than 70 ppt, set in 2016. The fifth compound, perfluoroheptanoic acid (PFHpA), lacks sufficient data to develop an individual AL. The current Action Levels are:


CT Drinking Water Action Level

(parts per trillion, ppt)

Perfluorooctane sulfonic acid (PFOS)


Perfluorononanoic acid (PFNA)


Perfluorooctanoic acid (PFOA)


Perflurohexane sulfonic acid (PFHxS)


These Action Levels are based on the most sensitive, human-relevant effects seen in laboratory animals exposed to PFOS (immune effects); PFNA, PFOA (developmental effects); or PFHxS (thyroid effects). This new chemical-specific approach reflects the evolving scientific evidence on the toxicity of PFAS and is more protective of public health than our previous AL (sum of “CT 5” = 70 ppt). Also, the resulting individual ALs are within the range of drinking water guidance and standards more recently derived by another federal agency (Agency for Toxic Substances and Disease Registry, or ATSDR, 2018, 2020) and by other states, including most of our neighboring states.


Q:  How do these chemicals get into drinking water?

A:  The way in which these chemicals reach groundwater is still being investigated. Drinking water contamination has occurred near industries manufacturing or using these chemicals to make consumer products. PFAS use at metal plating facilities for mist suppressant can also be a source of groundwater contamination. Because of their use in firefighting foams, it is possible that fire training schools, airports, and sites where there was a major fire may have releases of PFAS. Landfills can be sources of PFAS because many types of wastes that contain PFAS can end up in landfills. Once on the ground, these chemicals can gradually migrate down through the soil when it rains and affect groundwater. PFAS do not biodegrade and are known to be persistent in the environment. Once a release has occurred that has impacted groundwater, it is possible, depending on the magnitude of the release, for PFAS to travel far away from the release area.

Many consumer products also contain PFAS, so it is possible that PFAS can be washed down the drain and into septic systems, thus becoming  a source of groundwater pollution and potentially impact nearby wells. For more information on sources of PFAS, please refer to the Connecticut Department of Energy and Environmental Protection’s PFAS webpage.

Q:  There are thousands of PFAS chemicals. Why has CT only derived drinking water action levels for four of them?

A: At the time the CT Action Levels for PFOA, PFOS, PFHxS, and PFNA were developed, there were insufficient toxicity data to allow DPH to include other PFAS chemicals. The PFAS analytical methods currently used for drinking water analyzes for a total of 29 PFAS chemicals out of the thousands of PFAS that are currently known to exist. Of these 29 chemicals, recent testing in CT shows that PFBS and PFHxA are the most commonly detected PFAS that are not part of the current four individually developed Action Levels. To date, no federal agency has set a safe drinking water level for either PFBS or PFHxA. CT DPH monitors the evolving toxicity data for these and other PFAS chemicals to identify when new or updated Action Levels are needed.

There is another consideration for why PFAS chemicals like PFBS and PFHxA are not part of the current PFAS Action Level. PFBS and PFHxA are compounds with short-chain chemical structures and thus are very different from the four PFAS with Action Levels, which have long-chains. We know from studies of humans and laboratory animals that short-chain PFAS are eliminated from the body much more quickly (on the order of days to months in humans) than long-chain PFAS (on the order of years in humans). Because short-chain PFAS are removed so quickly from the body, they are less likely to build up in the blood to a level that could cause toxicity. This is supported by the limited toxicity data (mostly from laboratory animal studies) for PFBS and PFHxA that indicate these chemicals appear to be much less toxic than long-chain PFAS such as PFOA and PFOS.


Q:  If I have PFAS in my water, what precautions should I be taking for my pets, farm animals, home grown produce, and irrigation of my garden?

A: Pets 

Connecticut DPH has identified limited data about how PFAS might affect the health of cats and dogs. Out of an abundance of caution, homeowners can choose to use an alternative water source for their pets if their well water exceeds the Action Level.

Chicken eggs

There are good data that show that the amount of long-chain PFAS in chicken eggs is directly correlated with the amount of PFAS in drinking water consumed by hens (short-chain PFAS such as PFHxA and PFBS are not readily transferred from drinking water to chicken eggs). Results from a 2021 study indicate that hens exposed to drinking water with a combined level of PFOS, PFOA, and PFHxS that exceeds 3000 ppt (ng/L) are likely to produce eggs with PFAS concentrations that would exceed the limit set by the Australian Government for human consumption (the US Food and Drug Administration, FDA, has not set any limits for PFAS in foods). Therefore, DPH advises that water with the sum of PFOS, PFOA, and PFHxS concentrations greater than 3000 ppt not be used for hens if the hens are producing eggs for human consumption. This guidance assumes that hens do not have significant exposure to PFOS, PFOA, and PFHxS from soil and/or feed.

PFAS in milk, or meat

There are no data on the uptake of PFAS into the meat or milk of sheep or goats. However, PFAS has been shown to be readily absorbed and excreted into maternal milk of laboratory rodents, dairy cows and humans. In the past few years, several New England farms have detected PFOS in cow’s milk at levels considered ‘unacceptable’ for human consumption. Since the cows’ exposure to PFAS was mainly through contaminated feed (and possibly drinking water), Connecticut DPH is unable to determine the level of PFAS in drinking water that would produce unacceptable levels of PFAS in milk. Given the findings about uptake of PFAS into maternal milk of lab rodents, dairy cows, and humans, it is possible that sheep and goats exposed to elevated PFAS in their water source could accumulate elevated PFAS levels in their milk.  For this reason, DPH advises that water with PFAS concentrations greater than the Connecticut DPH Action Level not be used for livestock if the milk is used for human consumption.

With regard to human consumption of sheep or goat meat, there are no data on PFAS uptake into meat, but it is likely, that uptake would occur.  Thus, out of an abundance of caution, the homeowner could choose to use an alternative water source for the sheep and goats if they are being raised for meat consumption.

Connecticut DPH continues to monitor the rapidly evolving science on PFAS. As more definitive information becomes available, we will update this FAQ. 


Connecticut DPH has developed acceptable PFAS concentrations in water used to irrigate gardens. In developing these values, Connecticut DPH considered PFAS uptake into edible garden produce from irrigation water and consumption of garden produce by children and adults.  Connecticut DPH’s irrigation water screening levels are:

At water concentrations greater than these levels, Connecticut DPH advises against the use of water for irrigation of garden produce intended for human consumption.

It should be noted that these screening values (with the exception of PFHxS) were adopted from work done by the state of Maine. Maine did not derive an irrigation value for PFHxS so Connecticut DPH opted to use Maine’s value for PFOS as a surrogate for PFHxS (thus the values for PFOS and PFHxS are the same).

Q: Can I remove PFAS by boiling my water?

A: PFAS cannot be removed by boiling the water. In fact, it may increase the PFAS concentration as the water will evaporate, but all the PFAS will remain.

Q: I am a customer of a public water system. How can I find out if my water has been tested for PFAS?

A:  If you are concerned about PFAS in your public drinking water, Connecticut DPH recommends you contact your local water utility to learn more about your drinking water and to see whether they have monitoring data for PFAS or can provide any specific recommendations for your community.


Q: How do I know if bottled water is safe?

A:  Bottled water is regulated by the Department of Consumer Protection as a food product. Many retail water bottlers publish water quality testing data, and while PFAS chemicals are not regulated in bottled water, many bottlers do test for it and include the information on their web pages. Some water bottlers use numerous sources and water quality may vary depending on the source location. If you are making your own purchasing decisions about bottled water, make sure that when you search for water quality data, you are viewing the data from the correct source.

Effective October 1, 2021; sections 86 and 87 of Public Act 21-121 require that bottlers collect samples prior to any water treatment and annually test each DPH approved bottled water source in Connecticut for unregulated contaminants such as PFAS chemicals. There are currently four Connecticut DPH-approved sources for bottled water located in the state of Connecticut, and these are the sources that bottlers would be required to sample and test. If the results of such sampling exceed Connecticut's PFAS drinking water AL, then DPH may require the bottler to discontinue use of the source until it is rendered safe to drink.

Bottled water delivered to homes in conjunction with a DEEP investigation has been tested for PFAS per the contract DEEP has with its bottled water vendor.


Q:  How can PFAS affect my health?

A:  The main health concerns from ingestion of long-chain PFAS, such as PFOS, PFOA, PFNA, and PFHxS, come from studies in laboratory animals which consistently show effects on the liver and immune system, and on growth, reproduction, and fetal development. PFAS can also affect the endocrine (e.g., thyroid) and hormonal systems and can disturb blood lipids such as cholesterol in lab animals. Studies of human populations exposed to elevated levels of PFOS, PFOA, PFNA, and PFHxS generally support the effects seen in animals. Some studies of populations exposed to PFOA have also shown an increased risk for kidney cancer, and at very high exposure levels, for testicular cancer. Our bodies eliminate these long-chain PFAS very slowly, so they can build up over time with continued exposure. Therefore, even low levels in drinking water may increase your risk of developing a variety of health effects if exposure is long term (months to years). Exposure to PFAS above the Connecticut Drinking Water Action Level does not necessarily mean that health effects will happen. Short-chain PFAS, such as GenX (replacement for PFOA) and perfluorobutane sulfonic acid (PFBS, a replacement for PFOS), do not build up in the body over time; however, they have been shown to cause similar health effects in laboratory animals as their predecessors.

PFAS are not readily absorbed by your skin, so bathing, showering, swimming, and washing dishes in water containing PFAS is not a significant source of exposure.


Q:  Why have states set different acceptable levels for PFAS in drinking water?

A: There is no enforceable federal Maximum Contaminant Level (MCL) for PFAS; only a federal EPA lifetime health advisory for PFOA + PFOS that was set in 2016. Some States that have identified PFAS contamination have proactively developed drinking water standards and guidelines. While states use the same standardized risk assessment approach for developing acceptable drinking water concentrations, there are many points in the process where professional scientific judgement is needed. Different decisions in the risk assessment process can result in variations in drinking water standards and guidelines; each of which are scientifically defensible.

In addition, some states have set acceptable PFAS drinking water levels more recently than other states. Consideration of newer toxicological data about PFAS can result in differing acceptable levels.


Q:  Should I test my blood for PFAS?

A: Connecticut DPH generally does not recommend testing your blood for PFAS. There are several reasons why. A PFAS blood test can tell you what your levels are at the time the blood was drawn, but not whether levels in your body are “safe” or “unsafe” or whether your health has been or will be impacted by PFAS. Virtually everyone in the U.S. (and the world) has measurable amounts of PFAS in their body because PFAS chemicals are so widely used in commercial and industrial products. Many of the health issues that have been associated with exposure to PFAS (such as increased cholesterol and decreased thyroid hormone levels) commonly occur in the population even without high levels of PFAS in the blood. These health issues can be caused by many different factors, and there is no way to know or predict if PFAS exposure has or will cause a health problem. It can also be complicated to get a PFAS blood test. It is not a routine test, not many laboratories can analyze blood for PFAS, and it is likely that health insurance would not cover the cost. Finally, a PFAS blood test will not provide information to pinpoint a health problem, nor will it provide information about treatment.

However, if you are concerned about your exposures and wish to have your blood tested for PFAS, you should speak with your physician.


Q:  How can I limit my overall exposure to PFAS?

A: We can be exposed to PFAS not only through drinking PFAS contaminated water, but also through pathways such as: eating foods packaged in PFAS containing materials; using consumer products such as non-stick cookware, stain resistant carpeting, and water repellant clothing; and, eating fish contaminated with PFAS. Nearly everyone has low levels of PFOA, PFOS, PFNA and PFHxS in their blood. These background levels likely come from consumer products and food packaging. You may still have some PFAS in your body years after the chemicals have been phased out because of their slow removal from the body.  Limiting your use of these products and your consumption of PFAS-containing food can limit your overall exposure to PFAS. Consult the Connecticut Fish Consumption Advisory for information about eating fish caught in Connecticut waters and the US EPA for additional advice on how to limit your exposure to PFAS.



Q:  I have a well, should I test the water for PFAS? How can I test my well for PFAS?

A:  If your well is located near a suspected or probable source of PFAS, you might consider testing. PFAS testing is currently not broadly recommended for all private well users, because of the complexity of proper sample collection, cost, and the limited number of labs approved for testing for PFAS. If you’d like to consider testing, the list of labs certified to test for PFAS in drinking water can be found on the Connecticut DPH’s Environmental Laboratory Certification Program’s website.

Connecticut DPH encourages private well owners to test their drinking water for general potability and other common naturally occurring contaminants.  For general private well recommendations on what to test for, why and how often, please refer to the Connecticut DPH's website:


Q:  How does the State decide which wells are going to be tested for PFAS?

A: To date, the State of Connecticut has tested those private wells that are located near a confirmed exceedance of the Connecticut PFAS Action Level, as identified through independent testing performed by a public water system, remediation contractor or other entity. The State is in the process of developing a mapping application that can be used to identify areas with a higher likelihood to have been impacted by PFAS based on proximity to known or likely release areas.  Consistent with the recommendations in the Connecticut PFAS Action Plan, the State will use that tool to determine which communities may be most at risk of PFAS contamination going forward.


Q:  What happens if there are PFAS in my well?

A: If your well is being tested through a targeted investigation being conducted by the Connecticut Department of Energy and Environmental Protection (DEEP) and PFAS are detected in your well water above the Connecticut DPH Drinking Water Action Level, then DEEP will arrange to have bottled water delivered to you on an interim basis while the most appropriate long-term solution is determined. If you tested on your own and PFAS are detected, please notify the DEEP Remediation Division contact for your town and DPH at  for additional guidance.

Q:  Does the home water treatment system I have work to remove PFAS? What types of treatment address PFAS in drinking water?

A:  Viable treatment options for PFAS reduction include granular activated carbon (GAC) and point of use reverse osmosis (RO). Treatment effectiveness is dependent on treatment sizing, contact time, and how well the device is maintained. For specific devices, it may be best to check with the manufacturer of your treatment device.

To find products certified to reduce PFOA and PFOS, by the National Sanitation Foundation (NSF) please refer to: NSFProtocol P473 Drinking Water Treatment – PFOA & PFOS. There are currently no treatment devices certified to reduce PFAS other than PFOA and PFOS. 

Q: What type of water treatment system will be installed if my PFAS levels exceed the Connecticut Action Levels? Who will maintain my treatment system, and how often?

A: If your home is part of an investigation initiated by DEEP, then DEEP will arrange to have a treatment system installed at your home should your levels of PFAS exceed the Action Level, at no cost to the homeowner. Treatment will be dependent on case specifics. DEEP will also arrange to have your water treatment system routinely maintained and serviced by a State contracted water treatment professional.


Contacts & Resource 




External Resources


Circular Letters

2022-27 Environmental Health & Drinking Water Branch Update for Public Water Systems Regarding Per- and Polyfluoroalkyl Substances (PFAS)

2021-87 Bottled Water Sources to Sample for Unregulated Contaminants

2019-03 Reminder to Complete Land Use Inventory Table Source Water PFAS Vulnerability Assessment

2018-28 Environmental Protection Agency (EPA) Toxicity Assessments for GenX Compounds and Perfluorobutane Sulfonic Acid (PFBS)

2018-20 Requirement to Update an Evaluation of Source Water Protection Measures and Request to Sample Drinking Water Sources for Perfluoroalkyl Substances (PFAS)

2018-19 Drinking Water Section Update for Public Water Systems regarding Per- and Polyfluoroalkyl Substances (PFAS)

2016-16 EPA Drinking Water Health Advisory for Two Perfluorinated Compounds