Occurrence of Viruses in US groundwaters

In a study that may affect the upcoming Ground Water Rule, the authors of this article determined that because of the widespread occurrence of virus in groundwater, most well water supplies should be disinfected before distribution. Scientific data were needed to support the upcoming rule, and this study provides a snapshot of viral contamination of groundwater at the nation al level. This article looks at information regarding the occurrence of pathogens and microbial indicators in source waters and their relationships with different abiotic parameters such as water quality, geologic formation of groundwater sites, and other factors. Sites were selected based on their geological characteristics to match the national profile for groundwater sources. Two different microbial methods were used to detect viruses in groundwater sources, and during the study a new microbial detection methodology was field-tested. Results indicate that when a well tested positive once for any of the biological assays, it was likely to test positive in future samplings. This article also offers a strategy to predict the vulnerability of groundwater supplies to fecal contamination.