Between the ongoing controversy around fluoridated water and the recent discovery of a chemical in our water systems that may or may not be toxic, the safety of American drinking water is murky, to say the least.
And today, with a new report revealing that tap water is delivering harmful chemicals like PFAS (“forever chemicals”), heavy metals, and radioactive substances to millions of Americans—often at levels far beyond what scientists consider safe—it got even murkier.
The latest update to the Tap Water Database, from the non-profit Environmental Working Group (EWG), reveals that 324 contaminants were found in drinking water systems across the country, with almost all systems having some amount of detectable contaminants in its water. That’s according to safety data collected between 2021 and 2023 by EWG from nearly 50,000 water systems in every state (except New Hampshire, which did not provide its data).
“This is a wake-up call,” said EWG senior scientist Tasha Stoiber in a news release.
Consumers can search the database by zip code to see what specific contaminants were found in their local water systems.
“The impact of human activities on our environment inevitably trickles downstream, impacting our drinking water,” EWG senior science analyst Sydney Evans tells Fortune. She adds that while many of the contaminants have likely been long present in our water and are only being detected now because of improved scientific methods, others appear to be new.
“I would argue that a lot of it has been the way that chemicals and industries are regulated in this country—allowing for a huge number of chemicals to be approved without a whole lot of underlying research to prove that they’re safe,” she says.
Who regulates tap water?
Tap water is regulated by the Safe Water Drinking Act of 1974. The law, explains EWG vice president of government affairs Melanie Benesh, requires the Environmental Protection Agency to look at the contaminants that are in drinking water, set safe limits on them, and then require water utilities to implement those standards through regular monitoring, by installing treatment technologies, or by changing their drinking water sources.
“But a lot of those clean water limits are out of date,” Benesh says. “There are a lot of unregulated contaminants that probably should be regulated contaminants, and the process for adding new contaminants to that list is very slow.”
States are given further authority to set more stringent standards—something that 11 states (Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Washington, Wisconsin) have taken advantage of by setting standards for maximum levels of certain PFAS in drinking water.
The EPA set historic federal PFAS limits last April after determining that there is no safe exposure level in drinking water, as they are carcinogens. But those protections are now in limbo, as the U.S. Court of Appeals for D.C. paused lawsuits from both water utilities and the chemical industry, allowing the Trump administration more time to review the EPA limits—and raising fears that they could be made weaker.
California, though, just introduced legislation that would codify those limits within the state.
What chemicals are in water?
The following groupings of chemicals are among the most common, according to EWG, which says that, to keep them out of drinking water, utility companies would have to start using more advanced treatment protocols.
Disinfection byproducts
“We need to disinfect drinking water so that people don’t get different pathogens,” Evans explains. But the disinfection chemicals can then combine with other contaminants and organic matter in the water to make byproducts, “which, at low levels, are linked to things like bladder cancer,” she says. “There’s a balancing act that needs to be done there.”
Hexavalent chromium aka chromium-6 or chrome6
This is the cancer-causing chemical made notorious by the film Erin Brockovich, which documented the poisoning of drinking water in Hinkley, Calif. It gets into drinking water as industrial pollution or through erosion of soil and rock. There is still no national standard for chromium-6 in drinking water, as the EPA’s safety review of the chemical was stalled by pressure from the industries responsible for contamination. Toxic effects can include stomach cancer, liver and reproductive system damage, and lowered body weight.
Nitrate
Nitrate, from fertilizer, landfill, or animal waste runoff, “is another big one,” says Evans, adding that it can be naturally occurring at low concentrations. At high levels, she says, it has been known “to be particularly harmful to babies in the short term,” while more recent research has shown low levels linked to colorectal and other forms of cancer.
PFAS (“forever chemicals”)
This is the large group of long-lasting chemicals that break down extremely slowly over time, used widely, industrially, for things including firefighting foam, nonstick pans, clothing, food packaging, furniture, and textile coatings. Found widely in water, air, soil, and the blood of people and animals all over the world—and in the drinking water of over 143 million Americans—they are linked to a host of health effects at low levels, including immune system suppression, endocrine disruption, low birth rate, various cancers, reduced vaccine effectiveness, and liver damage. “We have a gap between what is legally allowed in drinking water and what the research shows is dangerous because [legal limits] are outdated,” says Evans.
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Perchlorate
Perchlorate, a toxic component of rocket fuel, is harmful to humans because it blocks the thyroid from taking in iodide, which is critical to its ability to regulate many bodily functions. Too little iodide can cause harm to metabolism and to physical and cognitive development, and puts children and developing fetuses at the most risk.
How to stay safe
The No. 1 way to know you are drinking safe water, says Evans, is to invest in a home water filter—a solution she says comes with “a caveat.”
“We recognize that it is not the universal solution, because whether it’s out there and available and effective or not, not everybody’s going to be able to take advantage of it,” whether due to time, energy, or cost, she says. “It’s just not an equitable solution.”
That being said, filtering your water at home is very effective, she says, as long as “you have the right filter for the job.” It’s why EWG tested a range, and included the search-by-zip feature in its new database, pointing first to what contaminants are in your local water and then to which filters best fit your situation. “Because not all types of filters are going to be effective for all contaminants,” she says, noting that the activated-carbon filter pitchers are the easiest and more affordable, while a reverse-osmosis system will be more effective and expensive.
Bottled water, meanwhile, should be avoided except in the case of natural disasters or other emergencies.
“The main issue that we have with bottled water is that there’s really no guarantee that it’s any better than your tap water,” Evans says. “Sometimes it can be, but a lot of times it’s not, and the testing, because it’s regulated by a different agency, is a lot less transparent.”
Further, she says, it’s less affordable, not environmentally sustainable, and could be made unsafe by its bottle’s plastic, which can break down and wind up in the water.
Finally, consumers can advocate for stronger tap water regulations. “Certainly, people can call their legislators,” says Benesh, who advises letting them know you believe in stronger limits—as well as preserving the in-limbo PFAS limits enacted by the EPA last year. “That’s certainly something that consumers can and should do.”
More on drinking water:
- The new fluoride study dividing the public health world as RFK Jr. calls for a ban on adding it to water
- Americans drink more water than almost every other country. Here’s why
- More than 113 million people are drinking tap water that contains a newly identified chemical—and nobody knows if it’s toxic or not
