Chemical & Engineering News: Scientists once thought that pathogens could not reach drinking water wells sunk into deep, protected groundwater aquifers. Nevertheless, over the past decade, researchers have identified diarrhea-causing viruses at a handful of deep bedrock well sites in the U.S. and Europe. Now, researchers in Madison, Wis., report where these pathogenic viruses may have originated. The viruses appear to seep from sewer pipes and then swiftly penetrate drinking water wells (Environ. Sci. Technol., DOI: 10.1021/es400509b).
The U.S. Environmental Protection Agency does not regulate the presence of viruses in drinking water, so many public water systems do not routinely test for them. In a 2007 study, a team of researchers, including Mark Borchardt, a microbiologist with the U.S. Department of Agriculture, and Kenneth Bradbury, a hydrogeologist at the University of Wisconsin-Extension, in Madison, investigated the integrity of aquifers confined beneath a thick layer of clay or shale (Environ. Sci. Technol., DOI: 10.1021/es071110+). Groundwater models predicted that surface contaminants would require tens to hundreds of years to reach wells in these aquifers, which typically sit more than 700 feet underground. Even if pathogens did find their way to the groundwater, they should be dead after that amount of time. "But we were shocked to find human-specific viruses—some of which were still infectious—in every well we sampled in Madison," Bradbury says.
