People can be exposed to PFAS through the various media, including drinking water, household dust, food packaging, and food. Where PFAS-containing firefighting foams and other industrial sources to the environment have contaminated surface water and groundwater, drinking water may be highly contaminated. PFAS have also been found in household dust, fast food packaging, and food products such as fish from contaminated lakes or rivers.

Our understanding on the impacts of PFAS in drinking water is limited to a handful of specific chemicals at present but is rapidly expanding as the U.S. Environmental Protection Agency (EPA) and other organizations conduct research on these chemicals. The most studied PFAS are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). EPA currently identifies PFOA as “likely to be a carcinogen”, which is a step below a “Carcinogenic” classification on the basis of limited to no human data. PFOS is currently identified to have “suggestive evidence of carcinogenic potential”, a step below PFOA.

In June 2022, EPA published interim lifetime health advisories for PFOA and PFOS which are at levels below what can reliably be measured in drinking water. Final lifetime health advisories were published for two replacement compounds, hexafluoropropylene dimer acid (HFPO-DA or “GenX”) and perfluorobutanesulfonic acid (PFBS). Collectively these health advisories noted that the health effects of PFAS may include cancer, liver effects, immunological effects, decreased birth weights, thyroid disease, decreased fertility, and cardiovascular disease.

Drinking water lifetime health advisories are developed by EPA and intended to provide information on contaminants that can cause human health effects and are known or anticipated to occur in drinking water. EPA has published lifetime health advisories for four PFAS: PFOA at 0.004 parts per trillion (ppt), PFOS at 0.020 ppt, GenX at 10 ppt, and PFBS 2,000 ppt. These lifetime health advisories are developed to indicate the level of these PFAS that can be safely present in drinking water without causing adverse effects to consumers over a lifetime of exposure, including sensitive subpopulations like pregnant mothers, immunocompromised individuals, and children.

EPA develops health advisories by reviewing animal and human health studies to determine the levels of exposure at which individual adverse health effects may occur. EPA will consider strength of the study, how the chemical moves through the body and breaks down, and the applicability of the study to humans. Ultimately, health advisories are reflective of the sensitive health endpoint (i.e., the adverse effect that occurs at the lowest level). For EPA’s recently published lifetime health advisories, the health advisory levels were derived for PFOA and PFOS based on a decreased response in 7-year-old children receiving the tetanus and diphtheria vaccine. The GenX and PFBS health advisory levels were derived based on critical liver effects in mice and observed hypothyroidism in newborn mice, respectively.

Health advisories are structured to indicate the level of the contaminant in drinking water at which the sensitive health effect does not occur and to indicate the broader health effects that may occur at higher levels.

The Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) includes 29 PFAS compounds. As of the drinking water lab certification page (on Feb. 1, 2024) collected in conjunction with UCMR 5 PFOA and PFOS were found above the EPA health advisory levels for 11.5% and 12.8% of public water systems, respectively. One public water system measured HFPO-DA ("GenX chemicals") above the health advisory level. PFBS has not been found above the health advisory level in any public water system. Of the remaining 25 PFAS, 17 were measured at or above their respective Minimum Reporting Levels (MRL) by at least one PWS (an increase from the 14 reported under the second data release). No PWSs have reported results at or above their respective MRLs for the final eight PFAS.

Contact your public water system to learn more about PFAS testing and results that may be available for your drinking water supply.

On April 10, 2024, EPA released its final rule setting drinking water standards for six per- and polyfluoroalkyl substances (PFAS).

The rule sets maximum contaminant levels goals (MCLGs) and maximum contaminant levels (MCLs) for the following six PFAS and their salts: PFOA, PFOS, perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), HFPO-DA, and PFBS.

Individual MCLGs and MCLs are established for both PFOA and PFOS on the EPA’s determination that these compounds are carcinogenic. Three additional MCLGs and MCLs are set for PFHxS, PFNA, and HFPO-DA at 10 ppt each. An additional MCLG and MCL has been established for PFHxS, PFNA, PFBS, and HFPO-DA using a hazard index of 1 when at least two compounds are present. A hazard index is a tool used to evaluate combined risk from exposure to a mixture of contaminants.

Initial monitoring must be complete by April 2027 and public notifications through consumer confidence reports (CCRs) will be issued for detections of these PFAS. Water systems subject to the rule will be required to comply with the standards by April 2029; violations of these standards will be reported within 30 days and on CCRs.

If you get your drinking water from a private well, you should have your water tested by a certified laboratory at least once a year. You can find information on how to sample for PFAS and where to send samples for analysis by contacting your state water laboratory certification officer. Contact information for your state can be found at EPA’s drinking water lab certification page. Additional information about well water testing from EPA is available on its private drinking water well FAQ page.

If you are concerned about PFAS in your drinking water, you may consider purchasing a home treatment device. However, in order to make a well-informed and cost-effective decision, consider:

• Checking with your water system or consumer confidence report to learn more about the amount of PFAS in your water.
• Identifying a device that has been independently certified to remove PFAS.

NSF International, the Water Quality Association, Underwriters Laboratories and CSA International all certify home treatment products for removal of contaminants. The relevant PFAS removal standard is NSF/ANSI Standards 53 and 58. If you choose to use a home treatment device, it is very important to follow the manufacturer’s operation and maintenance instructions carefully in order to make sure the device works properly.

Bottled water quality can vary. Bottled water in the United States is regulated by the U.S. Food and Drug Administration and is required to meet standards equal to the EPA’s tap water standards. There are also individual state standards. However, in most cases, you must contact the bottled water manufacturer for information about PFAS levels. EPA is currently not recommending bottled water based solely on concentrations of PFAS exceeding the health advisories.