While tap water is safe for most Americans, millions of residents are still exposed to contaminants from their faucets every year, according to National Geographic.
This World Water Day, our partners at NatGeo are working to shine a light on what people need to know about what comes out of their own faucets.
According to some experts, there's a gap between what's legal and what's safe when it comes to drinking water.
The Environment Protection Agency currently regulates 90 different contaminants in drinking water, from naturally occurring arsenic to hazardous lead, said Sarah Gibbens, a National Geographic environment writer.
Since Congress passed the Safe Drinking Water Act in 1974, the EPA has identified dozens more potentially dangerous chemicals in tap water.
"These are things that require a lot more research to prove they are harmful to human health and regulating them ultimately costs a lot of money, so the EPA has to do a lot of work to prove that these chemicals should be regulated in the first place," Gibbens said.
Last week, the agency proposed the first federal limits on harmful PFAS, also known as "forever chemicals," in drinking water.
Environmental and public health advocates have pushed for years for regulations on PFAS, or per- and polyfluorinated substances, which don't degrade in the environment. The EPA estimates the new rule could reduce PFAS exposure for nearly 100 million Americans, decreasing rates of cancer, heart attacks and birth complications.
The Environmental Working Group, an advocacy organization that works to get toxic chemicals out of water, lauded the EPA's PFAS proposal but has long argued that many federal regulations on drinking water are outdated and insufficient.
The nonprofit offers its own tap water database, which offers residents insight into what contaminants were detected in water at their local utilities.
Still, the EPA maintains that the U.S. "enjoys one of the world's most reliable and safest supplies of drinking water."
The Walt Disney Co. is the parent company of National Geographic Partners and this ABC station.
The Associated Press contributed to this report.