A sample jar of water is held up.

Is tap water safe to drink? Here’s what you really need to know.

Experts weigh in on the chemicals that can be found in drinking water, how it’s regulated, and what you can do if you’re worried about your water.

An employee at a San Diego water treatment facility tests the water for contaminants. Most people living in the U.S. have access to clean drinking water, but a small percentage amounting to millions of people are exposed to contamination every year.
Photograph by Donald Miralle, The New York Times/Redux

Most U.S. residents don’t need to worry about the safety of their tap water, but millions of Americans are still exposed to contaminants every year. 

It can take a water crisis to highlight where drinking water infrastructure is failing.

One of the most devastating water crises in recent memory was the lead contamination in Flint, Michigan's drinking water in 2014. As of January 2023, nine years after the initial contamination, residents are still dealing with the effects. And last year, a water crisis in Jackson, Mississippi left many of the city’s 150,000 residents without potable water, a problem that persists today

Here, drinking water experts from the EPA, academia, and advocacy groups weigh in on what you need to know about your tap. 

What are some of the common things in tap water—other than water? 

In the U.S., about 90 percent of people get their tap water from a public water system (PWS). Water from a lake, reservoir, river or aquifer is piped into a water treatment facility where chemicals are added to the water that bind to pollutants and are sifted out of the system. Some facilities also use bacteria-killing UV light. 

Chemical disinfectants such as chlorine or chloramine are then added to the water to help kill any pathogens remaining in the water and any that might be lurking in your pipes when the water travels to your home. 

Some water treatment facilities, from lack of funding or too little oversight, don’t effectively clean their water. In 2015, about 21 million people living in the U.S. were exposed to tap water that violated federal guidelines, according to a study published in 2018. 

Unsafe and therefore illegal levels of pathogens (bacteria and viruses), nitrates, arsenic, and harmful byproducts from disinfectants like chlorine were the most common sources of violations, says Maura Allaire, study author and a water quality expert at the University of California, Irvine.

How is tap water regulated? 

In 1974, Congress passed the Safe Drinking Water Act, which gave the Environmental Protection Agency (EPA) the authority to regulate public tap water. 

When something like lead, for example, is shown to be harmful to human health, the EPA can set a limit for how much is allowed in water supplies. Limits are based on what amount is safe for human consumption and what is technologically feasible for water treatment facilities to accomplish. 

But these limits don’t always result in water that is contaminant free. 

“There’s a gap between what is legal and what is safe,” says Sydney Evans, a science analyst at the Environmental Working Group (EWG). She adds that many regulations are based on decades-old science, which the EWG has argued makes regulations outdated and insufficient.

The EWG maintains their own tap water database where they set much stricter limits than the EPA, based on what they consider to be safe for human health. Their limits are determined by peer-reviewed studies, research done by state agencies, and staff scientists. 

What are PFAS, the latest chemicals to get EPA attention? 

Type “drinking water” into your search bar, and lately you’re likely to see articles about how it’s full of PFAS, pollutants sometimes referred to as “forever chemicals.” PFAS (per-and polyfluoroalkyl substances) is a group of thousands of chemicals with tight chemically-bound bonds that help them last in the environment for years.

Certain PFAS compounds have been linked to serious health issues, such as cancer. Recently, the EPA proposed new limits on six of these chemicals in drinking water. Studies conducted on drinking water show PFAS is common in drinking water supplies throughout the U.S., and as a result, these chemicals have been found in our blood.

The EPA rules proposed this month would be the first to meaningfully address PFAS pollution at the federal level and paves a way to remove a toxin that’s been contaminating drinking water for decades.

What about other unregulated contaminants?

New rules for currently unregulated contaminants will take time. PFAS, for instance, have been a known hazard for years, but it required large amounts of evidence and research before a rule could be proposed. 

“There is a significant challenge,” Eric Burneson, a director at the EPA’s Office of Ground Water and Drinking Water, says of proposing new regulations. “We need robust scientific information, and we need peer review of that information. We need to know about our ability to manage it. Can we measure it? Can we treat it?”

Answers to these questions help the EPA defend the potential cost of regulating a new chemical.

In addition to the 90 contaminants the EPA already regulates, there are dozens more the agency has identified as a threat to health and in tap water. They include 66 chemicals, 12 microbes, and all PFAS—instead of the six they recently proposed to limit. 

“We need further information to move forward,” says Burneson of regulating potentially harmful chemicals, but he adds, “They may be in drinking water, and they pose risks.” 

Who’s impacted the most by contaminated drinking water?

Rural, low-income communities face the most trouble accessing clean tap water; water treatment facilities there are most likely to violate EPA standards. Proximity to agricultural pollution, contaminated groundwater, and underfunded or understaffed treatment facilities put these communities at risk. 

An analysis of three decades of drinking water violations in the U.S. found some states were more likely to have poorer quality drinking water than others. States with agricultural hubs were particularly at risk.

Certain racial groups are also more likely to be exposed to poor drinking water. One study looking at California and Texas found Latino and Black communities faced a persistently higher cancer risk from their drinking water.  

(An environmental advocate weighs in on inequality and safe drinking water.)

What can you do if you’re concerned about your tap?

The EPA requires water utilities to publish annual reports identifying any potential health hazards in the community about their water supply. (You can find yours here.) 

When hazards emerge, securing clean drinking water can cost individuals. 

For short-term emergencies like a boil water notice, bottled water can be a useful resource.  

Bottled water bought and sold in the U.S. is regulated by the Food and Drug Administration, which regulates water based on the same standards the EPA has in place for tap water. Studies done on bottled water have found it’s no cleaner or safer than well-regulated tap water, but it is sold at several times the price of tap water and promotes plastic waste, an emerging drinking water threat

Filters are another option for addressing tap water concerns. They can be as simple as the relatively inexpensive filters that fit in your fridge or as complex as a thousand-dollar filtration system hooked up to home plumbing.

How do we make sure everyone has clean drinking water?

There are about 3,000 electric utilities in the U.S. but over 50,000 water utilities. While some serve as many as eight million people, about half of those facilities serve fewer than 500. Those smaller utilities are less likely to have full time operators or enough customers to pay for maintenance. 

With the right policies and enough funding, experts say clean tap water can be guaranteed for everyone.

“We have the technical know-how to provide safe drinking water,” says Allaire. “It’s a policy question of how do we make this a reality?”

Combining those smaller utilities, creating water contracts where one community purchases water from a larger utility, and paying for well-trained facility managers could all create more water for more communities.  

A new World Water Map allows people to find out about the water supply where they live. Typing in an address will reveal that area’s water gap—the difference between human demand for water and the renewable supply from sources such as rivers, lakes, and aquifers. The map—which was developed by National Geographic Explorer Marc Bierkens and Niko Wanders, with the support of the National Geographic Society, Utrecht University, and ESRI—also shows the regions where the water gap is highest and groundwater depletion most dire, including California’s Central Valley, Egypt’s Nile River Delta, and Pakistan’s Indus River Basin.

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