Study: Activated-Carbon Filtering Pitcher Found To Significantly Reduce Chemicals In Tap Water

Using an activated-carbon filtering pitcher is the most effective way to reduce disinfection byproducts in tap water, according to the results of a study conducted by Université Laval (Quebec, Canada) researchers.

The results of the study, funded by the Natural Sciences and Engineering Research Council of Canada, were announced on Nov. 2.

Researchers Steven Lévesque, Christine Beaulieu, Jean Sérodes, François Proulx and Manuel Rodriguez, all from Université Laval's Center for Research in Regional Planning and Development, measured concentrations of the two main drinking water disinfection byproducts -- trihalomethanes (THMs) and haloacetic acids (HAAs) -- in samples subjected to different types of indoor handling. These byproducts result from chemical reactions between chlorine used to disinfect water and organic matter normally present in it.

"They don't affect the smell or the flavor of water, but in high concentrations, they are suspected of increasing the risk of certain types of cancer," Rodriguez said.

Researchers subjected samples collected in private residences to three treatments often used to improve taste, smell and appearance of water: storing water in the refrigerator, boiling water followed by storage in the refrigerator and filtering water with an activated-carbon filtering pitcher followed by storage in the refrigerator. Analysis revealed that after a 48-hour period, these treatments reduced THMs by 30 percent, 87 percent and 92 percent, respectively. However, results were less convincing with HAAs: direct storage and storage after boiling had no effect on HAAs. The carbon-activated filter, on the other hand, reduced HAA concentration by 66 percent.

In spite of these results, Rodriguez does not recommend the systematic use of such filtering pitchers.

"If you live in a city with adequate water treatment facilities, HAAs are probably within regulation levels, and there's no need to subject water to additional treatment," Rodriguez said. "However, if I lived in a place where there were regular notifications to boil water or if I knew the water contained high levels of HAAs, I'd consider using home water-treatment devices."

Manuel Rodriguez: http://www.vrr.ulaval.ca/bd/chercheur/fiche/285969.html.

This article originally appeared in the 11/01/2006 issue of Environmental Protection.

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