Bottled Water vs. Tap Water

It's regulated by different agencies, with different missions. The U.S. Environmental Protection Agency oversees the quality of water that comes out of your tap, while the U.S. Food and Drug Administration is responsible for ensuring the safety and truthful labeling of bottled water sold nationally. States are responsible for regulating water that is both packaged and sold within its borders (which is most of the market), but one in five states doesn't even bother.

It's important to note that the federal government does not require bottled water to be safer than tap. In fact, just the opposite is true in many cases. Tap water in most big cities must be disinfected, filtered to remove pathogens, and tested for cryptosporidium and giardia viruses. Bottled water does not have to be.

Both kinds of water are tested regularly for bacteria and most synthetic organic chemicals, but city tap is typically assessed much more frequently. For example, bottlers must test for coliform bacteria just once a week; city tap needs to be tested 100 or more times a month.

Limits on chemical pollution for both categories are almost identical. The one place where bottled water might have the edge is in the case of lead; because many older homes have lead pipes, the EPA standard for tap water is less strict—one-third of the FDA's standard for lead in bottled water.

In 1999, after a four-year review of the bottled-water industry and its safety standards, NRDC concluded that there is no assurance that bottled water is cleaner or safer than tap water. In fact, an estimated 25 percent or more of water sold in a plastic bottle is really just tap water in a bottle—sometimes further treated, sometimes not.

Of the 1,000 bottles tested, the majority proved to be relatively clean and pure. About 22 percent of the brands tested, however, contained chemicals at levels above state health limits or industry recommendations in at least one sample. Especially if consumed over a long period of time, some of those contaminants could cause cancer or other health problems for people with weakened immune systems.

Though it's mostly safe, tap might at times also present issues. For example, lead and toxic “forever chemical” contamination of tap water can be widespread. Additionally, tap water contamination can be a particular concern if you live near an industrial facility or in a rural community with a higher likelihood of pesticide or fertilizer contamination, or if you get your water from a private (unregulated) well.

Under right-to-know provisions in the drinking water law, all public water systems must provide annual water quality reports (also known as “consumer confidence reports”) to their customers. (That’s soon to be twice a year for people served by larger systems.) This report indicates whether your water system committed any violations and whether any contaminants subject to mandatory sampling were detected at your water utility. You can use this list to identify the contaminants you want to target with a filter in your home. You can also test your water yourself—but if you don’t know which contaminants you are looking for, you will want to order an analysis for a wide range of contaminants. Standard consumer test packages are available through large commercial labs. Contact your state drinking water program (see the EPA’s list here) or the EPA Safe Drinking Water Hotline (800-426-4791) for a list of laboratories certified in your state.

Once you have a list of contaminants of concern at your location, you can search for a filter that’s certified to remove those contaminants. This document helps identify filters certified by NSF to reduce different contaminant classes. Filters may also be certified by other organizations, but certification to NSF standards is the key to look for when evaluating products. To ensure you get optimal protection, ensure your filters are correctly installed and well maintained (see more details here) and change the cartridges on the manufacturer’s recommended schedule. 

Even though both the federal government and most states have bottled-water safety programs, regulations don't adequately assure consumers of either purity or safety. For example, PFAS  are not regulated in bottled water, and recent testing by academic researchers indicated that several brands were contaminated with these chemicals. 

A few state programs (for example, those in Massachusetts and New York) maintain lists of the sources, but not all do. You can learn some information by carefully checking the label and even the cap; if it says "from a municipal source" or "from a community water system," this means it's derived from tap. If you don't find any information on the bottle, you can call the bottler or the program in your state or the state where it was packaged and ask about the source. 

Recent research suggests there might be cause for concern. One study found that a liter of bottled water contained about 240,000 tiny pieces of plastic, meaning that bottled water could be a major source of human exposure to micro- and nanoplastics. And a growing body of evidence suggests that microplastics can harm our health—in particular, our digestive, reproductive, and respiratory systems—and that nanoplastics may be even more harmful. Researchers have also found that consumers who drank bottled water instead of tap water ingested substantially more microplastics every year.

Additionally, plastic bottles can leach a wide variety of harmful chemicals into bottled water. Research shows these contaminants include the heavy metal antimony along with chemicals that disrupt hormones like estrogen and testosterone. Bottled water packaged in glass bottles is also a concern due to the plastic tubing and filters that may be used to process the water and any accompanying plastic caps or liners—components which can also shed microplastics and leach chemicals.  

This story was originally published September 23, 2023, and has since been updated with new information and links.