Nearly Half Of US Drinking Water Contains PFAS — How Worried Should We Be?

Talk of tap water safety has picked up in the U.S. over the last few years—and for good reason. Crises like those in Flint, Michigan, and Jackson, Mississippi, have demonstrated how fragile our water systems really are, and research has questioned how safe the chemicals in our water (particularly PFAS) really are.

These conversations reached a renewed fervor this month following new U.S. Geological Survey (USGS) research1 that found potentially toxic PFAS in nearly half of U.S. drinking water sources tested.

Per- and polyfluoroalkyl substances (PFAS) are a group of human-made chemicals known as "forever chemicals" because they linger in the environment—and in human bodies.

Exposure to high levels of PFAS has been linked to challenges with metabolic2 and thyroid health, adverse birth outcomes3, and in some extreme cases, higher incidents of cancer. PFAS are less than 100 years old (we first started using them to make water- and oil-resistant products in the 1940s), so there are still a lot of unanswered questions about how prevalent they actually are in our water supply.

Up until this point, most PFAS testing has been done at water treatment plants—not kitchen sinks themselves. In-home testing can be logistically difficult, but it's something that the USGS wanted to prioritize in this round of research because, as environmental organic chemist Kelly L. Smalling, MSPH, explains, "That's where exposure actually happens."

"Most of the information available on PFAS is at the drinking water treatment plant or in the surface water and groundwater wells that actually supply them. But then there are miles of infrastructure between the treatment plant and your home," Smalling, who worked on this new study, says on a call with mindbodygreen. "We don't really know how or if it changes as it moves through the distribution pipeline."

To find out how many PFAS are actually present at the tap level, the USGS worked with a network of volunteers to collect water samples from 716 residences across the U.S. This included a mix of rural and urban residences and public water supplies and private wells. Volunteers sent samples to laboratories to be tested for 32 types of PFAS.

In this study, 45% of U.S. drinking water samples contained at least one type of PFAS. The most common types of PFAS were PFBS4, PFHxS, and PFOA—found in approximately 15% of the samples. Exposure to these specific chemicals has caused adverse health effects in animal research, but their impacts on humans are unclear.

The amount of PFAS found in tap water varied from state to state and region to region. "Based on our analysis, higher concentrations of PFAS and more PFAS were observed in taps that were collected near urban centers, as well as potential sources of PFAS like airports, wastewater treatment plants, and military installations," says Smalling. Potential hot spots include more developed areas like the Eastern Seaboard, the Great Plains, the Great Lakes, and central and Southern California.

Tap water tested from rural areas in the Arid West and the Pacific Northwest did not contain any PFAS, Smalling notes.

"The other piece of the important puzzle is private wells," she adds. We know very little about the water quality of privately owned wells, so the USGS aimed to test nearly as many private wells as they did public water sources in every state sampled. They found that across the board, PFAS levels were actually pretty consistent between private and public water sources.

If you're concerned about chugging down PFAS, Smalling recommends doing some research on your water supply. Some states are required to monitor and report PFAS levels while others aren't, so check on your local policy and the results of your latest water quality report for more information. (This Public Water Supply map from the EPA can get you started.)

Right now, there is no federal drinking water standard on PFAS. However, the EPA just introduced a new regulation that would limit the use of six of the most common PFAS. The agency is also conducting water quality tests across the country5 to help them determine any other unregulated contaminants of concern.

Until tighter nationwide standards are put in place, the EPA says that using an activated carbon filter at home is your best bet for removing PFAS from tap water. You can find these filters in pitchers, nozzles that attach to your sink, and in whole-home water purification systems.