Arsenic Levels in Drinking Water To Be Reduced

Advisory Report - June 2000

Arsenic Levels in Drinking Water To Be Reduced
The U.S. Environmental Protection Agency (EPA) is proposing to reduce the current arsenic standard from 50 parts per billion (ppb) to 5 ppb in drinking water.  The proposal would provide additional protection to at least 22.5 million Americans from cancer and other health problems.

All 54,000 community water systems serving 254 million people would be subject to the new standard.  The EPA estimates that only 12 percent of community water systems--approximately 6,600 systems--would need to take corrective action to lower arsenic levels in drinking water to 5 ppb.  Ninety-four percent of these water systems serve fewer than 10,000 people each.  Water systems in western states and parts of the Midwest and New England that depend on underground sources of drinking water will be most affected by this proposal.

In general, arsenic can contaminate drinking water through natural processes, such as erosion of rocks and minerals.  Arsenic can also contaminate drinking water when used for industrial purposes.  Arsenic is found at higher levels in underground sources of drinking water than in surface waters, such as lakes, reservoirs and rivers.

The EPA estimates that reducing the standard of arsenic in drinking water to 5 ppb will provide additional protection to at least 22.5 million Americans from cancer and other health problems.  Exposure to arsenic at high levels poses serious health effects as it is a known human carcinogen.  In addition, it has been reported to affect the vascular system in humans and has been associated with the development of diabetes.

The current arsenic standard of 50 ppb was set by EPA in 1975, based on a Public Health Service standard originally established in 1942.  A March 1999 report by the National Academy of Sciences concluded that the current standard does not achieve the  EPA’s goal of protecting public health and should be lowered as soon as possible.  Under the Safe Drinking Water Act Amendments of 1996, the EPA is required to promulgate a final rule by January 1, 2001.

According to the EPA, water suppliers must deliver to their customers annual drinking water quality reports (or consumer confidence reports). These reports will tell consumers what contaminants have been detected in their drinking water, how these detection levels compare to drinking water standards, and where their water comes from. The reports must be provided annually before July 1 and, in most cases, are mailed directly to customers’ homes.  Contact your water supplier to get a copy of your report, or see if your report is posted on-line.

For additional information, visit www.epa.gov/safewater, or call the EPA's drinking water hotline at (800) 426-4791.