Millions in the U.S. May Be Drinking Groundwater Tainted With ‘Forever Chemicals’

The next time you run your tap for a refreshing drink of water, you might want to consider its source. More than 20% of the United States’ population may be using H20 that’s been contaminated by toxic chemicals.

Per- and polyfluoralkyl substances (PFAs) are compounds that have become better known as “forever chemicals” due to how difficult they are to break down. For several years, the EPA has required monitoring for PFAs in public water systems serving more than 3,300 people. However, United States Geological Survey scientists found gaps in the data collected by the EPA. To get a better picture of how many Americans could be drinking water contaminated by PFAs, they came up with their own model, which they published in the journal Science. The findings were alarming: They found somewhere between 71 and 95 million people in the contiguous United States could be drinking water with detectable levels of the chemicals.

Groundwater is what it sounds like: water that’s found in underground pores, such as aquifers. The water can be supplied to households either through public utilities or private wells, and it is the source of drinking water for around 107 million Americans.

The USGS’ results were based on over 1,200 groundwater samples taken by the agency between 2019 and 2022. The USGS scientists then analyzed the data, using a machine learning model, plotting out the chances of contamination by geographic area. That was then compared to previous surveys on how many people in any given area relied on groundwater for drinking water.

In terms of absolute numbers, Florida and California have the most people whose public water supply could be contaminated, at 9.5 and 13 million people, respectively. On a per capita basis, Massachusetts takes the crown, with a shocking 86 to 98% of people relying on groundwater from public supplies that could be contaminated.

The presence of chemicals with an ominous nickname is obviously alarming, but Andrea Tokranov, a research hydrologist at the USGS who led the study, pointed out that there’s a silver lining. The new model “can help prioritize areas for future sampling to help ensure people aren’t unknowingly drinking contaminated water,” she said in a statement. “This is especially important for private well users, who may not have information on water quality in their region and may not have the same access to testing and treatment that public water suppliers do.”

While some studies have indicated PFAs can have adverse effects on human health, there’s still much we don’t know. As the CDC points out, many studies involving exposing animals to PFAs have used higher levels than what a human would normally be exposed to in everyday life. The CDC also pointed out that the effects can depend on how often people are exposed to the chemicals, and at what levels. Outcomes can also depend on an individual’s personal constitution, access to safe water and healthcare, and other factors.

Still, there has been evidence linking PFAs to some pretty horrible health conditions in humans, including issues with fertility, developmental delays in children, higher cholesterol levels, reduced immune responses, and increased risk of prostate, kidney, and testicular cancer, according to the EPA.

To make the data as accessible as possible, the USGS also released an interactive map, which shows the probability of PFA contamination in the local supply of groundwater. Anyone checking out the map should understand that the map is based on a mathematical model, and is not necessarily definitive. The results are also for local groundwater, which might not be representative of what’s in the drinking water that comes out of your tap.

If you’re looking for some good news in this, the findings are slightly more encouraging than what the USGS found in a study it published last year. In that survey, based on water samples collected in 716 kitchen sinks, it was estimated that almost half of the population was drinking water containing PFAs. So, in a weird way, this could count as progress.