EWG's Tap Water Database — 2021 UPDATE

picture of test tube and beaker in laboratory


UPDATE: March 14, 2023 – The Environmental Protection Agency recently proposed new limits to tackle drinking water contamination from the toxic “forever chemicals” known as PFAS. The proposal targets six notorious PFAS: PFOA, PFOS, PFNA, PFHxS, PFBS and GenX.

The limits, known as maximum contaminant levels, or MCLs, are the highest level of a contaminant allowed in drinking water. The MCLs announced are 4 parts per trillion, or ppt, for PFOA and 4 ppt for PFOS. For the other four PFAS the agency is proposing using a “hazard index” which is a tool used to address cumulative risks from mixtures of chemicals.

November 2021


PFAS are per- and polyfluoroalkyl substances, a family of thousands of synthetic chemicals used in hundreds of categories of products, including nonstick pans, stain repellent carpets, waterproof clothing, fast food wrappers and firefighting foam, among many other examples.

Research studies show that even at low levels, exposure to PFAS may result in serious adverse health effects, including suppression of the immune system, cancer, endocrine disruption, accelerated puberty, liver damage and thyroid changes.

PFAS are persistent in the environment, including contaminated water supplies, and they are known as “forever chemicals” because they accumulate in our bodies.

Analyzing state and federal data, EWG scientists estimate that more than 200 million Americans could have PFAS-contaminated drinking water. EWG scientists have also identified more than 40,000 industrial or municipal sites that are potential sources of PFAS contamination in all 50 states and Puerto Rico, as of July 2021.

Between 2013 and 2015, the Environmental Protection Agency required U.S. drinking water utilities to test for six different PFAS. The results greatly underestimate the extent of contamination, because the reporting limits were 10 times higher than could be detected in water. Since the EPA’s test results were released, multiple states conducted further tests, and some have set state level drinking water limits.

States that have passed enforceable tap water standards include Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York and Vermont.

Arizona, Iowa, Kentucky and Rhode Island have proposed standards.

Some states have recommendations or notification levels, including Alaska, California, Colorado, Connecticut, Delaware, Illinois, Minnesota, North Carolina, New Mexico and Ohio.

Each state conducted tests before releasing guidelines or standards.

At least three states have banned PFAS in certain products. In the past two years, California has banned PFAS in firefighting foam, cosmetics, food packaging and children’s products. Maine banned PFAS in all new products in July 2021. Connecticut banned the use of PFAS in food packaging in July 2021.

Guidelines for protecting public health

There are still no national, legally enforceable drinking water standards under the federal Safe Drinking Water Act for any of the hundreds of PFAS compounds currently in use.

EWG recommends a health guideline of 1 part per trillion, or ppt – equivalent to 0.001 part per billion, or ppb – for limiting PFAS in drinking water. This guideline is based on the chemical and toxicological similarity of many PFAS chemicals and applies to the entire class of PFAS detected in water.

PFOA, the most infamous PFAS family member, is a carcinogen that severely polluted the drinking water near a DuPont manufacturing plant in Parkersburg, W.Va.

A decade of studies documented links between exposure to PFOA and testicular and kidney cancer, thyroid disease, ulcerative colitis, high cholesterol, and pregnancy-induced hypertension and preeclampsia. Later studies linked exposure to endocrine disruption and developmental health impacts, and reduced effectiveness of vaccines.

California’s Office of Environmental Health Hazard Assessment in 2021 drafted a public health goal for PFOA of no more than 0.007 ppt in drinking water. EWG recommends this health guideline for this specific PFAS. The stricter limit – compared to the 1 ppt guideline for other PFAS – is based on studies that show increased kidney cancer risk in humans associated with exposure to PFOA.

Is there a safe level of PFAS in water?

The short answer is no – there is no safe level for PFAS in your water.

The longer answer is that EWG’s health guidelines for PFAS in drinking water are based on evidence of increased cancer risk, reduced effectiveness of vaccines and the impact of PFOA and PFOS on mammary gland development. These health guidelines are below the reporting level that the EPA mandated in its testing, which means for every positive test we indicated, the result was above the health guideline.

There is growing agreement among scientists that the entire class of PFAS may be harmful to human health. For exposure to PFOA, government scientists in New Jersey and Germany indicate that a safe level in drinking water may be zero, a figure based on the widespread exposure already occurring from other sources, such as food.

There is also growing awareness that replacement chemicals for PFOA, PFOS and the other PFAS are harmful to human health and the environment.

And a peer-reviewed study released in 2019 refutes claims by the chemical industry that the next generation of PFAS is safer than PFOA and PFOS. GenX, the chemical that DuPont is using to replace PFOA, has also been linked to cancer in lab animals.

The EPA is beginning the process of developing national drinking water standards for PFOA and PFOS, taking steps in January 2021 to set legal limits for them. It also said it will require most public utilities to test their drinking water for an additional 29 PFAS chemicals between 2023 and 2025.

In October 2021, the EPA released a PFAS “Strategic Roadmap” that includes a plan for speeding up efforts to set a national drinking water standard for PFOA and PFAS by 2023. It also includes other types of testing and reporting and commits to focusing on and engaging with the communities that have been most affected by PFAS pollution.

But these steps are long overdue and fall short of what’s needed to start cleaning up PFAS contamination.

Instead, PFAS should be regulated as a class of chemicals, since there is potential for similar health harms and environmental persistence for all types of PFAS. Regulating each PFAS chemical one by one will take far too long.

How can I protect my family from PFAS?

For home water filtration options, reverse osmosis and activated carbon filters can reduce or eliminate PFOA and other PFAS contaminants. Active carbon filters are less effective at removing the shorter-chain replacement chemicals, but we don’t know the extent of water contamination by these replacement chemicals.

Exposure to PFAS is not limited to water. It may also occur through food and food packaging. EWG recommends that people lower their exposure to fast food wrappers, often coated in PFAS, by preparing meals at home and avoiding paper tableware and microwave popcorn. PFAS can also be found in personal care products.

EWG’s interactive map of known detections of PFAS in the U.S. was updated in October 2021, and our map of suspected industrial discharges of PFAS – locations of sites known to produce or use PFAS, or suspected of using – was updated in July 2021. Wherever PFAS are discharged, they can seep into the ground and contaminate the drinking water supply.

Read EWG's guide for more tips on avoiding PFAS.


A. Blum et al. The Madrid Statement on Poly- and Perfluoroalkyl Substances (PFAS). Green Science Policy Institute. 2014. Republished in Environmental Health Perspectives, May 2015. Available at

Danish Ministry of the Environment. Perfluoroalkylated Substances: PFOA, PFOS and PFOS: A Evaluation of Health Hazards and Proposal of a Health Based Quality Criterion for Drinking Water, Soil and Ground Water. Environmental Project No. 1665, 2015. Available at

Danish Veterinary and Food Administration. Ministry of Environment and Food of Denmark. Fluorinated Substances in Paper and Board Food Contact Materials (FCM). 2015.

DuPont GenX. 8(e) Filings with EPA, 2010–2013. Available at

See also: Sharon Lerner, New Teflon Toxin Causes Cancer in Lab Animals. The Intercept, 2016. Available at

Environmental Working Group. Teflon Chemical Harmful at Smallest Doses. 2016. Available at

EWG. Scientists in N.J., Germany Support ‘No Safe Level’ of Teflon Chemical in Drinking Water. 2016. Available at

New Hampshire Department of Environmental Services. In-Home Water Filtration Options for PFCs in Household Drinking Water. 2016. Available at

New Jersey Drinking Water Quality Institute. Health-Based Maximum Contaminant Level Support Document: Perfluorooctanoic Acid (PFOA). 2016. Available at

New Jersey Department of Environmental Protection. Draft Technical Support Document: Interim Specific Ground Water Criterion for Perfluorononanoic Acid (PFNA, C9). 2017. Available at

L. Schaider et al. Fluorinated Compounds in U.S. Fast Food Packaging. Environmental Science & Technology Letters, 2017, 4(3). Available at

See also: EWG, Many Fast Food Wrappers Still Coated in PFCs, Kin to Carcinogenic Teflon Chemical. 2017. Available at

X. Hu et al. Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants. Environmental Science & Technology Letters, 2016, 3(10). Available at

Z. Wang et al. A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)? Environmental Science and Technology, 2017, 51(5). Available at