In the United States, approximately
48 million people are served
by private wells. Unlike public water systems, private well water
quality is not monitored, and there are few studies on the extent
and sources of contamination of private wells. We extensively investigated
five private wells to understand the variability in microbial contamination,
the role of septic systems as sources of contamination, and the effect
of rainfall on well water quality. From 2016 to 2017, weekly or biweekly
samples (n = 105) were collected from five private
wells in rural Pennsylvania. Samples were tested for general water
quality parameters, conventional and sewage-associated microbial indicators,
and human pathogens. Total coliforms, human Bacteroides (HF183), and pepper mild mottle virus were detected at least once
in all wells. Regression revealed significant relationships between
HF183 and rainfall 8–14 days prior to sampling and between
total coliforms and rainfall 8–14 or 0–14 days prior
to sampling. Dye tracer studies at three wells confirmed the impact
of household septic systems on well contamination. Microbiological
measurements, chemical water quality data, and dye tracer tests provide
evidence of human fecal contamination in the private wells studied,
suggesting that household septic systems are the source of this contamination.
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