The tap water of nearly 280 million Americans is provided by community water systems monitored and regulated by the U.S. Environmental Protection Agency. While some public systems deliver a more pure product than others, the water coming out of your tap is overwhelmingly safe and can match almost all bottled water.
Cities and towns across the United States began disinfecting drinking water in the early 1900s, and the rate of waterborne illness dropped dramatically.
In 1900, for example, there were about 100 cases of typhoid fever for every 100,000 persons living in the United States, according to the Centers for Disease Control and Prevention. In 2006, the rate had declined to 0.1 cases for every 100,000 persons, and 75 percent of those cases included people who had traveled overseas.
Still, testing by water utilities has found more than 250 contaminants in the tap water Americans drink, according an analysis by the Environmental Working Group. Many of the contaminants found were at levels that are legal under the Safe Drinking Water Act or state regulations, but above levels authoritative scientific studies have found to pose health risks, according to the EWG. In addition, there are no legal limits for the more than 160 unregulated contaminants the tests detected in the nation’s tap water, the group says.
The EWG's Tap Water Database lets you search specifically for drinking water where you live so you can get specific information about contaminants that may be coming out of your tap.
The EPA sets standards and regulations for the presence and amount of about 90 different contaminants in public drinking water, including E.coli, Salmonella, and Cryptosporidium species. Some of the contaminants — such as trihalomethanes, which can increase the risk of cancer — are a byproduct of the disinfection process. Other contaminates such as copper can come from corrosion of your household plumbing.
Some contaminants may cause gastrointestinal illness, reproductive problems, and neurological disorders, particularly for children, pregnant women, the elderly and people with weakened immune systems.
The federal Safe Drinking Water Act requires public water suppliers to provide customers with annual drinking water quality reports, or consumer confidence reports (CCRs). The reports detail what contaminants have been detected in their drinking water and how these detection levels compare to national drinking water standards. Your water system's CCR may be posted online.
But if you’re among the estimated 15 percent of Americans, or about 45 million people, who get their water from private ground water wells — you’re on your own. Private wells are not subject to EPA regulations.
Depending on your level of concern about the tap water — and the details in the water quality report from your water utility — you may want to install a home filter or buy a water filter pitcher.
Water filters using activated carbon will absorb organic contaminants that make the water smell and taste funky. Some carbon filters will also remove metals, such as lead and copper, and some cleaning solvents and pesticides.
Ion exchange filters will remove minerals, including fluoride.
A reverse osmosis unit removes most — but not all — contaminants. Such systems use a good deal of water, however.
Editor's note: This story has been updated since it was originally published in December 2012.