The Hopkins study, supported by a $300,000 grant from the U.S. Environmental Protection Agency, will focus on water drawn from wells alongside the Wabash, Ohio and Missouri rivers near Terra Haute, Ind.; Louisville, Ky.; and Kansas City, Mo. The wells are all owned by the American Waterworks Service Co., which is providing $256,000 in labor, equipment and other in-kind support for the study.

The company is testing a natural filtration method developed in Europe two decades ago to produce cleaner drinking water from polluted rivers such as the Rhine. "The focus in the 1970s was mainly to get rid of taste and odor problems and to remove hazardous materials like pesticides and hydrocarbons," Bouwer says. "But there has been limited recent work to look at how it affects the pathogens and by-products of disinfection. We will be doing work that is more relevant to today's concerns."

The study will pay particular attention to disinfection by- products, a source of growing alarm. After vegetation decays, tiny bits of surviving plant material make their way into a water source. In its natural state, this organic matter may affect how water tastes or smells, but it poses no health risks. However, when treatment plants add a disinfectant to kill pathogens, the chemical can also react with the harmless organic matter, creating not-so-harmless by-products. For example, chlorine mixed with the plant material can produce chloroform, a suspected carcinogen.

For water utilities, that poses a dilemma. "Viruses and other pathogens in drinking water are a real threat," says Bouwer. "But the trade-off is, if you use disinfectants to kill them, you're going to create these by-products that are harmful themselves."

One solution is to remove more of the harmless plant matter before a disinfectant is added to the water. One way is to "feed" this material to bacteria in the soil before the water reaches the treatment plant. Bouwer's team--which includes William
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Contact: Phil Sneiderman
prs@jhu.edu
410-516-7160
Johns Hopkins University
7-Jul-1998