This study investigated the potential for distribution system biofilm bacteria to elevate copper concentrations in drinking water. Biofilms were sampled from household copper reticulation pipes and grown on R2A agar. Laboratory coupon experiments were used to determine the effect of single isolate biofilms on aqueous copper concentrations. The majority of biofilm bacteria did not affect copper concentrations in comparison to sterile controls. However, several bacteria including Acidovorax delafieldii, Cytophaga johnsonae and Micrococcus kristinae were shown to significantly elevate copper concentrations in drinking water. In contrast, the bacteria Rhodococcus sp. and Xanthomonas maltophilia were shown to significantly decrease copper levels in comparison to controls. The significance of biofilm bacteria to increase copper concentrations in drinking water has implications for public health by increasing concentrations to levels toxic to humans.

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