What's In Your Water?

This article edited by Katherine Unger in the May 12th 2006 issue of Science/AAAS provides an informative assessment of the current state of the U.S. water supply.

The vast majority of Americans who rely on groundwater to drink are swigging more than just H2O. A new survey of groundwater stored by the U.S. Geological Survey (USGS) found that volatile organic compounds (VOCs) are found in 90% of aquifers, although generally at levels considered safe for human consumption.

VOCs come from commmonly used products such as gasoline, cleaning products, plastics, and paint. The 17-year USGS study, released last month, tested water samples from 98 groundwater aquifers and 3500 public and private wells for 55 compounds. Scientists identified 42 such compounds, the most common of which was chloroform. It was found in 7% of aquifers, 5% of domestic wells, and 11% of public wells. But fewer than 2% of the samples had VOC levels above those determined by the Environmental Protection Agency to be harmful to human health.

Senior author John Zogorski says the findings underscore the necessity of 'continuing monitoring efforts to go back and understand the sources' of contamination. And Erik Olson, director of the drinking-water program at the Natural Resources Defense Council in Washington, D.C., cautions that many of the chemicals identified could be harbingers fo worse contamination. For instance, 3% of aquifer samples contained MTBE--a highly mobile gasoline additive that affects water's taste and odor. Its presence could mean that slower moving and more toxic gasoline compounds may not be far behind.