AWWA JAW59043

Fecal pollution in some groundwater sources may be intermittent or low. Little data exist regarding the comparative performance of a large variety of indicator tests to detect fecal contamination in groundwater sources tested multiple times, rather than just once or a few times, and on an equal-volume basis. The proposed US Environmental Protection Agency Ground Water Rule specifies the use of either Escherichia coli, enterococci, or coliphage tests to detect contamination, but it is not clear if these are the best indicator tests to use. This study showed that detecting fecal pollution in some groundwater sources is easy, but in others it is easier said than done. In addition to using groundwater vulnerability assessments and well sanitary surveys, water purveyors need to sample their groundwater sources often, over an extended period of time, and use the most reliable monitoring tools available. Data from this study, although limited, show that fecal pollution in a well with known contamination was detected most often by the total coliform bacteria indicator test, followed by the fecal coliform bacteria test, then the E. coli and enterococci tests. Further, if method issues can be resolved, 1-L volumes should be tested rather than the currently specified 100-mL volumes. Includes 54 references.