Drinking water supplies for 70 million Americans in 48 states are contaminated with arsenic at concentrations above the level scientists say increases the risk of cancer, according to nationwide test results collected in EWG's Tap Water Database.
The Environmental Protection Agency's legal limit for arsenic in tap water is 10 parts per billion, or ppb, a level exceeded in 2015 in the water supplies for more than half a million people in 32 states. But the EPA's legal limit is 2,500 times higher than the public health goal set by California's Office of Environmental Health Hazard Assessment, endorsed as a health-protective EWG Standard.
The public health goal, 0.004 ppb, is the level expected to cause no more than a one-in-a-million risk of cancer over a lifetime. When the EPA's legal limit was set in 2001, the agency published an analysis showing that 10 ppb is not safe, potentially causing up to 600 cancer cases for every 1 million people exposed for a lifetime. A 2010 draft report from the EPA suggests that arsenic could be up to 17 times more toxic than previously estimated, but political pressures blocked publication of the draft.
Arsenic is a notorious, deadly poison. Exposure to even tiny concentrations of arsenic in drinking water is proven to increase the risk of bladder, lung and skin cancer, and possibly liver, kidney and prostate cancer as well. The risk of cancer is even higher when exposed during early childhood and pregnancy. Prenatal exposure has also been shown to harm the immune system, cause behavioral problems and impair intelligence.
Tests conducted by almost 50,000 utilities showed that, in 2015, arsenic contamination of tap water was highest in the following communities:
- The Española Water System in Española, N.M., serving more than 10,000 people, reported an average level of 13.6 ppb.
- The Camino Real Regional Utility Authority in Sunland Park, N.M., which serves almost 21,000 people, reported an average level of 11.3 ppb.
- The City of Andrews water utility in Andrews, Texas, serving more than 11,000 residents, reported an average level of arsenic of 25.8 ppb in 2015. Andrews installed a water treatment system in December 2015, which appears to have reduced arsenic concentrations in city water.
EWG’s Tap Water Database has in-depth research on arsenic and many other contaminants found by water utilities across the nation. You can plug in your zip code and see exactly what has been detected in your water, as well as the associated risks.
Our water filter guide can tell you what kind of filters are effective in removing the particular contaminants in your tap water. While most contaminants can be removed with inexpensive filters, arsenic is more difficult to get out, requiring reverse-osmosis or carbon block filter systems.
Ultimately, the burden of ensuring that tap water is safe should not fall on individual Americans. Citizens should speak out to pressure state and federal regulators and elected officials to ensure the well-being of all Americans by setting strict, health-protective legal limits for contaminants in tap water.