This page, Per- and Polyfluoroalkyl Substances (PFAS) in drinking water, is part of
This page, Per- and Polyfluoroalkyl Substances (PFAS) in drinking water, is offered by

Per- and Polyfluoroalkyl Substances (PFAS) in drinking water

See frequently asked questions and answers.

This fact sheet answers frequently asked questions about the detection of Per- and Polyfluoroalkyl Substances (PFAS) in drinking water. It includes information about a Maximum Contaminant Level (MCL) in drinking water for PFAS, finalized by the Massachusetts Department of Environmental Protection (MassDEP) in October 2020.


What are PFAS?

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals manufactured and used in a variety of consumer products and industries throughout the world. Two of these PFAS chemicals, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), have been the most extensively produced and studied. They have been used to make carpets, clothing, fabrics for furniture, paper packaging for food, and other materials (e.g., cookware) that are resistant to water, grease or stains. They are also used in aqueous firefighting foam and in a number of industrial processes. Because these chemicals have been used in an array of consumer products, most people have been exposed to them.

Many PFAS are no longer being produced in this country; the largest manufacturer completely stopped PFOA/PFOS production in 2002. PFAS are still being produced in other countries and may be imported into the US in limited quantities. The US Environmental Protection Agency (EPA) and the PFAS industry launched the PFOA Stewardship Program in 2006 to work toward ending the production of PFOA and other PFAS.

While consumer products and food are a large source of exposure for most people, drinking water can be an additional source in the small percentage of communities where these chemicals have contaminated water supplies. Such contamination is typically localized and associated with a specific facility, (e.g. an industrial facility where these chemicals were produced or used to manufacture other products or where firefighting foam was used).

How are PFAS regulated?

In October 2020, the Massachusetts Department of Environmental Protection (MassDEP) finalized an MCL for PFAS in drinking water of 20 nanograms per liter (ng/L) or parts per trillion (ppt). MassDEP’s MCL applies to six PFAS, including PFOA, PFOS, perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), and perfluorohepatanoic acid (PFHpA) and perfluorodecanoic acid (PFDA). The MCL is an enforceable standard, set at a level that is safe to drink for an entire lifetime.

There are currently no established federal regulatory limits for PFAS in drinking water.

How can PFAS affect my health?

There are many gaps in the current scientific literature, but it is believed that PFAS may affect human health. Most research is based on animal studies and scientists are still unsure of the difference between how animals and humans respond to PFAS. PFAS exposures in these studies have been associated with changes in thyroid, liver, and kidney function, as well changes in hormone levels. PFOA and PFOS have also been shown to cause developmental effects to fetuses during pregnancy and in breastfed infants.

Can PFAS cause cancer?

There is no conclusive evidence that PFAS cause cancer, though several animal studies and legal cases have identified a possible link between them. The EPA reports there is suggestive evidence that PFOA and PFOS can increase the risk of cancer. Both the EPA and the National Toxicology Program are continuing research on the cancer potential of PFAS. 

If I drank water above the MassDEP MCL would it harm my health?

Drinking water at a level above MassDEP's MCL does not necessarily mean that you have been harmed or will get sick. This is because the MCL is based on a level that is safe to drink for an entire lifetime. By convention, a value such as the MCL is designed to overestimate exposure and ensure that sensitive individuals are protected. For example, the MCL assumes that individuals drink only contaminated water and are also exposed to PFAS from sources beyond drinking water, such as food. Several safety factors are additionally applied to account for the differences between animals and humans and the differences from one human to another human. Under this scenario, a risk would be expected only if an individual continuously drinks only contaminated water at a level significantly higher than the MCL. The most important thing you can do if PFAS contamination has been identified in your water is to limit exposure, and stop drinking the water.

What should I do to limit exposure?

PFAS are found at low levels in the environment, consumer products, and food, so it is nearly impossible to eliminate all exposure. If PFAS contamination has been identified in your drinking water, there are several ways to limit your exposure such as drinking and cooking with bottled water, and using pre-mixed baby formula, or bottled water for reconstituting powdered formula. Routine showering and bathing are not significant sources of exposure.

Additional Resources for