What’s coming out of your tap?

Lead-poisoned drinking water in Flint, Michigan shocked the nation, is likely to lower the IQs of thousands of the city’s children, and will cost taxpayers nationwide hundreds of millions of dollars. But our problems with drinking water aren’t limited to lead or to Flint. What should you be paying attention to in the water where you live?

America’s drinking water is in trouble:

  • According to an investigation by USA Today, nearly 2,000 (out of 155,000) public water systems in all 50 states delivered water with too much lead to their customers sometime during the past four years. One sample from an elementary school in Ithaca, New York, had enough lead to qualify as “hazardous waste.”
  • This spring, a jury ordered Exxon Mobil to pay $236 million to the state of New Hampshire to help clean up water sources contaminated with MTBE, a chemical the company added to its gasoline.
  • Northern Alabama residents and their local public water system are suing 3M, accusing the company of polluting their drinking water source, the Tennessee River, with PFOA, a chemical used to manufacture nonstick surfaces.
  • About 20 percent of the groundwater used for drinking water in California contains high levels of one or more contaminants like arsenic, uranium, and nitrate, the U.S. Geological Survey recently found.

It’s clear that children are the most vulnerable to contaminants in water. But what about adults?

“A contaminant in water may have more of an impact on a growing fetus or child, but there still can be harmful consequences for adults,” says Jeffrey Griffiths, of the Tufts University School of Medicine. Griffiths chaired the drinking water committee for the Environmental Protection Agency’s Science Advisory Board.

Take lead. “There’s no safe amount, no matter what your age,” says Griffiths. “The incidence of high blood pressure is higher in adults who’ve been exposed to lead, and now there’s evidence that exposure in adulthood could accelerate cognitive decline.”1,2

Even if tap water had a small but legally permissible amount of lead, “there’s no way I would drink that water,” says Griffiths. “I would not expose my family, my neighbors, or anyone else.”

water coming out of a tap

The same goes for arsenic

Utilities are allowed to deliver water with up to 10 parts per billion (ppb). “But there’s no safe level,” says Griffiths. “It’s a really clear carcinogen for lots of cancers, and it causes metabolic problems. If my water had any arsenic in it, I wouldn’t drink it. End of sentence.”

Then there’s the unintended damage utilities do when they treat their water. Disinfectants like chlorine can react with organic compounds in the water to produce so-called disinfection byproducts

Some are carcinogens. “You want to get the optimal balance between the level of disinfection that gets rid of bad bugs and viruses and a minimal exposure to those carcinogens,” says Griffiths.

In 2006, when the EPA began to phase in a lower limit for disinfection byproducts, it estimated that the new limit would prevent 280 cases of bladder cancer a year.

What can you do?

  • Check your Consumer Confidence Report. “If you get your water from a public utility, find out what’s in your town’s water,” says Griffiths. To see your report, which water utilities are required to issue every year, go to epa.gov/ccr or call the EPA’s Safe Drinking Water Hotline at 800-426-4791. The report will flag any substance that exceeds its maximum contaminant level(MCL). That’s the highest concentration allowed in drinking water. It will also tell you what the utility is doing to fix any problems.
  • Get your water tested. The Consumer Confidence Report can’t tell how much lead is in your water because lead may be coming from pipes in your home (seep. 8). And there’s no report for people who draw their water from a private well. Solution: Get your water tested. For a list of certified labs in your state, call the Safe Drinking Water Hotline or go to epa.gov/dwlabcert and click on “Contact information for certification programs and certified laboratories.”
  • Get a filter. If your water is high in any contaminant, “I would get a filter,” says Griffiths. Ditto if you don’t want to deal with testing or reports or the environmental cost of bottled water. What to buy? Most filters will make your water taste better. But the best way to tell whether they also get rid of the contaminants you're concerned about is to check their certification with NSF International.

1 Environ. Health Perspect. 117: 574, 2009.
2 Am. J. Physiol. Heart Circ. Physiol. 295: H454, 2008.


water coming out of a faucet

What is it? A metal used in plumbing.

How does it get into drinking water? If your home was built before 1986, the service line—which brings water in from the street—could be made from lead. And no matter when your home was built, “there could be lead in your indoor plumbing,” says Tufts University’s Jeffrey Griffiths.

What’s more, “Congress, in its infinite wisdom, used to say that fixtures with up to 8 percent lead could be sold as leadfree,” adds Griffiths. (Now it’s only a quarter of 1 percent.) So if you have a faucet that was purchased before 2014, it could be leaching lead.

“If you take that first glass in the morning, the water that was up against the fixture all night may give you a big slug of lead,” says Griffiths. That’s why, if you don’t have a filter, “you should run your cold water in the morning.”

How do you know if it’s in your water? Only by testing your home’s water.

How can it harm you? No level of lead is safe. It accumulates in our bodies, damaging the brain, kidneys, and other organs, and leading to lower IQ, cognitive decline, and high blood pressure.1,2 At greatest risk: children and pregnant women.

“Where you have the opportunity to minimize your exposure to lead, you should take it,” says Susan Korrick, an environmental epidemiologist at Brigham and Women’s Hospital and the Harvard T. H. Chan School of Public Health.

1 Environ. Health Perspect. 117: 574, 2009.
2 Am. J. Physiol. Heart Circ. Physiol. 295: H454, 2008.

Disenfection byproducts

water testing

What are they? Hundreds of mostly chlorine-containing compounds.

How do they get into drinking water? Public water systems typically treat their water with disinfectants like chlorine, chloramine, and ozone. Those chemicals can combine with microscopic residues in the water (from decomposed leaves, for example) to form DBPs.

How do you know if they’re in your water? Look for “Total Trihalomethanes” in your Consumer Confidence Report. They shouldn’t exceed 80 ppb (parts per billion).

How can they harm you? DBPs may slightly increase the risk of bladder cancer, which is why the Environmental Protection Agency limits their levels in public water systems.1

1 nepis.epa.gov/Exe/ZyPDF.cgi/2000E99D.PDF?Dockey=2000E99D.pdf.

Rx drugs

prescription drugs

What are they? Antibiotics, antidepressants, and other prescription drugs.

How do they get into drinking water? Drug residues that people excrete are flushed down toilets. The EPA recently tested wastewater effluent from 50 of the biggest water utilities. (That’s treated sewage, which is released into rivers and lakes that may be used as sources of drinking water.) Traces of at least one prescription drug turned up in every sample.1

How can they harm you? They probably don’t, says the EPA’s Mitch Kostich. The amounts are so minuscule “that you would have to drink two quarts of wastewater every day for decades, usually for an entire lifetime, before you would be exposed to even one therapeutic dose,” he says.

How do you know if they’re in your water? You don’t. Water utilities aren’t required to include prescription drugs in the Consumer Confidence Report.

1 Environ. Pollut. 184: 354, 2014.


water drain pipe

What is it? A chemical used to manufacture nonstick pans, stain-resistant carpets, and other consumer goods. It is no longer being produced, but persists in the environment.

How does it get into drinking water? Traces are everywhere (but there’s not enough in nonstick pans to worry about). The highest levels are in areas—like West Virginia and upstate New York—where factories that used PFOA discharged it into waterways.

How do you know if it’s in your water? You don’t. Utilities monitor its presence, but don’t have to report levels to their customers.

How can it harm you? There is “suggestive evidence” that high levels of PFOA cause cancer, especially kidney and testicular cancer, says the EPA.1 About one out of every 100 smaller public water utilities exceeds the level that the EPA recommends.

1 epa.gov/sites/production/files/2016-06/documents/drinkingwaterhealthadvisories_pfoa_pfos_updated_5.31.16.pdf.

Other contaminants

gas pump

MTBE. It’s a gasoline additive that reduces carbon monoxide and ozone levels in car emissions. It has largely been replaced by ethanol. While MTBE that leaked from gasoline pipelines and storage tanks into the soil can take years to degrade, ”it is not clear if exposure to MTBE causes long-lasting health effects,” says the American Cancer Society.1 Water utilities aren’t required to include MTBE in the Consumer Confidence Report.

rocket lifting off

Perchlorate. It occurs naturally in rock. It’s also used in rocket fuel and explosives, which is why it’s more likely to be found in drinking water in areas near military facilities. Perchlorate interferes with the uptake of iodine into the thyroid gland, which can lead to an underactive thyroid.2 The EPA doesn’t require water utilities to include perchlorate in the Consumer Confidence Report, but that may soon change.

1 cancer.org/cancer/cancercauses/othercarcinogens/pollution/mtbe.
2 atsdr.cdc.gov/toxfaqs/tf.asp?id=893&tid=181.


plane crop dusting

What is it? A toxic element that’s found naturally in rocks, soil, water, and air.

How does it get into drinking water? Naturally occurring arsenic can leach into water sources. So can arsenic that’s used in pesticides and in manufacturing.

How do you know if it’s in your water? Arsenic levels are listed in the Consumer Confidence Report. Your water shouldn’t have more than 10 ppb. That’s a compromise between what’s safe and what’s practical.

What’s safe? There is no safe level of arsenic, says the Environmental Protection Agency. Yet according to a 2009 survey, the arsenic in 7 percent of the private wells in the United States exceeded 10 ppb.

How can it harm you? Arsenic can cause bladder cancer. Its presence in wells in New England may explain why that region has a 20 percent higher incidence of bladder cancer than the national average.1

Arsenic may also affect your brain, say several studies that are troubling but can’t prove cause and effect:

Elementary school children in Maine who lived most of their lives in homes where the well water contained 5 ppb or more of arsenic scored about 5 points lower on IQ tests than children whose well water averaged less.2

And in two rural Texas counties where the arsenic in groundwater averaged about 6 ppb, the more arsenic in their tap water, the lower adults scored on tests of language, executive function, and memory.3

1 J. Natl. Cancer Inst. 108: djw099, 2016.
2 Environ. Health 13: 23, 2014.
3 Int. J. Environ. Res. Public Health 8: 861, 2011.