Harmful chemicals in tap water: how to protect your family’s health

Most people assume the water that flows into their homes is clean. After all, if it’s coming out of the tap, someone’s checked to make sure it’s safe. Right?

The truth is, though most tap water in the United States is clean and safe, it’s relatively easy for a variety of substances to get into your water. Here’s what to know about the safety of your tap water, plus simple tips you can follow to help safeguard your home.

The journey of tap water

To understand the safety of your water, it helps to understand the journey it takes from its original source to your kitchen sink.

For most people in the U.S., water comes from a local source such as a public well or reservoir. From there, it flows to a drinking water plant controlled by local government or a local company.

At the treatment plant, the water is filtered and disinfected to remove particles, metals, chemicals, and germs. It is tested to be considered clean, safe, and ready to drink. This type of water, known as municipal water, is regulated by the U.S. Environmental Protection Agency (EPA).

The treated water next travels through large underground pipes called water mains. Any building or home receiving municipal water also has a water service line, which is a pipe that brings water from the water main into the home.

Municipal water is not the only source of water in the U.S. More than 43 million people—roughly 15 percent of the population—get their drinking water from private wells, according to the EPA.

After it rains, water that is not used by plants and vegetation seeps underground until it reaches a body of water called a groundwater aquifer. Private wells draw their water from this source. Unlike municipal water, private well water is not tested or regulated by the EPA. The only way to know the safety of your private well water is to get it tested yourself.

What chemicals might be in your water?

Water from municipal or private well sources can become contaminated with a variety of substances. These may include:

• Heavy metals, such as lead
• Naturally occurring (though still dangerous) substances, like arsenic, uranium, and nitrates
• Harmful chemicals, such as hormone-disrupting chemicals (also known as endocrine-disrupting chemicals or EDCs)
• Bacteria and viruses

Exposure to any of these is linked to a range of serious health issues. But because many of these potentially harmful substances are often tasteless, odorless, and colorless, there may be no clues to tip people off about contaminated water.

A 2023 study from the U.S. Geological Survey, for example, revealed that nearly 50 percent of U.S. tap water from both municipal and private well sources contains at least one type of PFAS. PFAS stands for per- and polyfluorinated alkyl substances. PFAS are known as “forever chemicals” because, once released into the environment, they last almost indefinitely. They are also considered to be endocrine-disrupting chemicals. Exposure to PFAS may contribute to a broad range of health effects including cancer, obesity, reproductive harms, and liver damage.

In April 2024, the EPA for the first time issued a rule to reduce PFAS exposure in drinking water. Prior to that, PFAS was not regulated by the EPA.

While most municipal water is safe, at least 9 percent of water systems fail to meet water quality standards for a variety of reasons, according to a 2022 study published in AWWA Water Science, a journal from the American Water Works Association. Each year, that translates into an average of 1 million people getting their municipal water from systems with health-based violations.

Why might your water be contaminated?

The likelihood of potentially harmful substances making their way into water lines depends on local contamination sources, features of the environment, and whether you have private well water or municipal water. Factors that may contribute to chemicals in tap water include:

• Natural disasters: Floods, for example, can disrupt and overwhelm local water systems, allowing dangerous chemicals to enter the water supply.
• Fracking: The extraction (removal) of oil and gas from underground rock, called fracking, can contaminate local water.
• Proximity to farmland: Farms that use pesticides and fertilizers can put nearby communities at risk when chemicals flow from fields when it rains.
• Aging infrastructure: Lead in pipes, broken pipes, and combined sewer overflow systems all affect drinking water quality. Aging infrastructure in institutional settings like schools or childcare facilities can also contribute to contaminated water.

History and policy are closely related to infrastructure, which means that issues with water quality don’t affect all communities equally. Communities of color, those who have historically experienced segregation, and/or those with under-investment in local infrastructure may be more likely to have contaminated water. Exposures like these can contribute to a range of health impacts, including a higher risk of chronic illness. (Read more about how history and policy can contribute to health disparities.)

Lead may also be a hazard

Historically, many water service lines that connect water mains to homes were made with lead. These lead water lines were banned in the U.S. in 1986, but there are still an estimated 9.2 million lead service lines across the country. Many older homes may also have pipes, solder, or fixtures made with lead. If you have private well water, older pipes running from your well to your home and inside your home may also contain lead.

There is no safe level of lead exposure. And yet, millions of U.S. families use lead-contaminated water to drink, wash and cook food, and make baby bottles every day.

Children are especially vulnerable to the health risks of heavy metals and chemicals in tap water like lead. Their growing bodies absorb more than adults do and they are affected by even small amounts of these substances. Childhood lead exposure can contribute to a range of health issues, including behavioral difficulties, developmental delays, and neurological disorders, to name some.

What’s more, modern plumbing doesn’t always use the safest materials, even if it’s lead-free. Some plastic pipes, for example, can contaminate the water that flows through them. Vinyl chloride—a potential carcinogen (cancer-causing substance)—can leach from pipes made from PVC (polyvinyl chloride). This is especially the case in plastic pipes made before 1977.

Is it safer to get your water from a private well?

While water that comes directly from the earth beneath your home may seem healthier than water that travels from unseen sources, private well water may be affected by a range of harmful substances. These include:

• Arsenic: This naturally occurring heavy metal, often found in groundwater, is a known carcinogen. As many as 2.7 million people in the U.S. may be using wells with high levels of arsenic, according to a 2021 report from the U.S. Geological Survey.
• Nitrates: These chemicals are found in soil and water, often due to fertilizers and animal waste, and may seep into well water. When ingested by people, they’re turned into nitrites, which can be toxic in large quantities. Nitrates should be tested in your area’s water supply during dry and rainy seasons, because levels of contamination are affected by weather patterns.
• Bacteria: Several types of bacteria and parasites can contaminate well water, especially after flooding, according to the Centers for Disease Control and Prevention (CDC). Giardia, for instance, can cause nausea and vomiting. Private wells should be tested for bacteria, particularly after flooding.
• Carcinogens: A variety of potentially cancer-causing agents, including byproducts from fuel and plastic products, can seep into groundwater.

“You can’t always taste, smell or see dangerous particles in well water,” notes Molly Kile, ScD, the co-Principal Investigator of Oregon State University’s ASPIRE Children's Environmental Health Center. Private well water is not regulated by the EPA, so the only way to know what is in your drinking water is to get it tested. Kile recommends testing your private well water yearly.

Ideally, a certified laboratory can determine the type of testing that’s appropriate for your location. This sort of professional testing can be expensive, but the benefit is that a professional company can tailor their approach to your needs. The EPA has a directory of drinking well water programs that can help you find certified laboratories in your area. Your local public health authority can also be a resource to ask about common concerns, such as chemicals from agriculture or industry that may make their way into your local aquifer.

If you don’t have the resources to pay for a certified tester to come to your home or if prefer the convenience of taking a sample at home, you can buy a kit that lets you mail a sample to a lab. Just be sure the kit uses a state-certified laboratory, as described by the EPA. Skip DIY kits that have you analyze the water at home. They are less reliable than sending a sample to a lab.

If your area experiences earthquakes or has had a land-use change (such as new logging, fracking, or flooding), Kile recommends having your water retested, as these events can affect the quality of your groundwater.

Nationally, there is a free online class called The Private Well Class, a collaboration between the Rural Community Assistance Partnership, the University of Illinois, and the EPA. It covers how to care for your well and ensure the water remains safe to drink.

Once you know what’s in your well water, you need a filter that will clean it. Some homes that have private well water need a filtration system (see more below) that will target the specific chemicals, metals, or bacteria in the water, based on your annual water test.

How to keep your water safe

If you have reason to believe your water may be unsafe, follow these steps to help take care of yourself and your loved ones:

Get your water tested

If you use municipal water, you can contact your local public health authority to make sure it is being tested. Your supplier is also required to inform you if your water becomes unsafe at any time during the year. As several recent incidents across the country have demonstrated, however—including in Sunland Park, New Mexico; Jackson, Mississippi; and Flint, Michigan—residents may not always get accurate or timely information about the quality of their tap water.

If you have private well water, you should have your water tested every year. The results of a test can also help you determine what other steps you might need to take to ensure the safety of your water, such as buying a filter (more below).

Sign up for local alerts

Sign up for your city or town’s local alert system to know when your water supply is experiencing issues. Pay close attention to the alert system after major storms and natural disasters, as these can affect water conditions.

Invest in a high-quality filter

Regardless of your water source, every home could use a good water filter. A water filter is your last line of defense against chemicals in tap water and sometimes the one protection that you can personally control. The Environmental Working Group (EWG) has created helpful guides to safe drinking water and shopping for water filters. They cover various filter types across a range of prices.

Endocrine-disrupting chemicals (EDCs) are a growing concern in the water supply. EDCs can alter your body’s hormones and contribute to a host of health concerns, including reproductive issues. Kile notes that testing your water for EDCs such as PFAS is often very expensive, so your money may be better spent if you purchase a filtration system that can remove PFAS from your water.

Find out if you have lead pipes

Any home built before 1986 (including homes with private wells) should be checked for a lead service line. All you’ll need is a coin, a magnet, and a few simple steps. The EPA also offers a guide to checking your service line for lead.

If it turns out you have lead pipes, the safest approach is to replace them. Some areas may offer cost-free programs to replace lead service lines, but you will likely need to hire a plumber to replace lead pipes or fixtures inside your home.

If you rent and discover you have lead pipes, start a conversation with your landlord. While they are not legally required to replace the pipes, they should do so. If that doesn’t work, refer to your local license and inspections department to see what regulations there are in your area.

Let the faucet run after sitting idle

When your water has not been in use for six hours or more, run your water before using it. Specifically, run your water one minute for every 50 feet that your sink sits from the street. This can help to flush your pipes and reduce the amount of lead and contaminants in the water.

Avoid plastics whenever possible

If you’re worried about your water supply, whether from municipal water or a private well, you’re not alone. As many as 94 percent of Americans buy bottled water, many with the hope of having cleaner drinking water. It may be convenient, but it’s not a sustainable answer.

Over time, bottled water is more expensive than using water filters, even considering that filters need to be replaced regularly. There’s also often little or no difference between bottled water and tap water in terms of cleanliness or safety.

“It would be great if all bottled water came from a spring,” says Linda Kahn, MPH, PhD, assistant professor in the Department of Pediatrics and the Department of Population Health at the NYU Grossman School of Medicine in New York City. “But most often, it comes from the tap water supply for the water bottling factory.”

In other words, bottled water often reflects the water quality of the town where it’s packaged. That quality depends on the strength of the town’s infrastructure, which may not be very different from yours.

What’s more, bottled water carries the added risk of plastic particles and chemicals that may come from the bottle itself. Among several types of chemicals, some plastics contain EDCs. Kahn recommends avoiding single-use and reusable plastic bottles. Opt for a stainless steel or aluminum bottle instead.

“If you are in a situation where you must use a disposable plastic bottle, don’t reuse it,” Kahn advises. “Plastic water bottles are known to release more chemicals with repeated use, especially after they are smooshed or cracked in any way.”

Keep plastic bottles out of the sun and in a cool place to help prevent further leaching of chemicals into your water. And don’t let them sit around for a long time. The longer the water stays in plastic, the more opportunity there is for chemicals to seep into the water.

Isabella Andreozzi, MPH, is the program coordinator at the Philadelphia Regional Center for Children’s Environmental Health (PRCCEH), affiliated with the University of Pennsylvania and the Children’s Hospital of Philadelphia. She administers the Translation Core that implements community-based children’s environmental health programs. PRCCEH strives to improve the health and wellness of children across the country, by focusing on lead poisoning, air pollution, climate change, asthma, and toxic chemicals.

To learn about other everyday environmental risks—like non-stick pans, candles, and plastic baby teethers—visit our Guide for Safe, Non-Toxic Gifts. For information on eliminating household dust (which can collect harmful chemicals) and choosing safer cleaning supplies, read 10 Simple Cleaning Tips to Help You Breathe Better at Home.