An unexpected temporal pattern of coliphage isolation in groundwaters sampled from wells at varied distances from reclaimed water recharge sites

Potable and monitoring wells located in close proximity to a large groundwater rechargeproject which utilizes a blend of surface water and reclaimed wastewater for recharge were tested for coliphage over a period of 6 months to assess the potential for virus migration. During the first 3 months FRNA phage were detected once at a shallow monitoring well. In late summer, an unexpected pulse of phage was detected in all wells, including control sites, suggesting an ecological phenomenon independent of recharge operations. Cubic and filamentous F-specific coliphage, consistent with the Leviviridae and Inoviridae groups, and a noncontractile tailed phage consistent with the Siphoviridae family were detected. There was no discernible relationship between recharge operations and the pattern of phage populations detected. Phage were detected using a host designated HS12, a variant of HS(pFamp)R (Debartolomeis, J. and Cabelli, V. J. (1991) Evaluation of an Escherichia coli host strain for enumeration of f male-specific bacteriophages. Appl. Environ. Microbiol. 57, 1301.). During the study it was found that HS12 contained a temperate Myoviridae phage; Myoviridae phage were subsequently excluded from the results. A total of 26 production wells, including 3 control sites, were sampled monthly and 6 monitoring wells were sampled every two weeks. Water reclamation plant effluents and river water upstream of effluent discharges were randomly sampled. The concentration and distribution of phage isolated was quite different in chlorinated effluent compared to river water. The majority of isolates from reclaimed water were filamentous DNA F-specific phage suggesting this group was more resistant to chlorine. Groundwater samples were analyzed using a novel large volume enrichment technique that proved very sensitive for detecting low concentrations of phage.