Occurrence, Concentrations, and Risks of Pharmaceutical Compounds in Private Wells in Central Pennsylvania.

Over-the-counter and prescription medications are routinely present at detectable levels in surface and groundwater bodies. The presence of these emerging contaminants has raised both environmental and public health concerns, particularly when the water is used for drinking either directly or with additional treatment. However, the frequency of occurrence, range of concentrations, and potential human health risks are not well understood, especially for groundwater supplies. Private wells are often not tested for contaminants regulated by drinking water standards and are even less frequently tested for emerging contaminants. By partnering with the Pennsylvania Master Well Owner Network, water samples were collected from 26 households with private wells in the West Branch of the Susquehanna River basin in central Pennsylvania in winter 2017. All samples were analyzed for six pharmaceuticals (acetaminophen, ampicillin, naproxen, ofloxacin, sulfamethoxazole, and trimethoprim) and one over-the-counter stimulant (caffeine). At least one compound was detected at each site. Ofloxacin and naproxen were the most and least frequently detected compounds, respectively. Concentrations from the groundwater wells were higher than those of nearby surface water samples. However, risk calculations revealed that none of the concentrations measured in groundwater samples posed significant human health risk. A simple, physicochemical-based modeling approach was used to predict pharmaceutical transport from septic absorption field to groundwater and further elucidate variations in detection frequencies. Findings indicate that although septic tanks may act as contaminant sources for groundwater wells, the human health impacts from trace-level pharmaceuticals that may be present are likely minimal.

Water quality and management of private drinking water wells in Pennsylvania.

Pennsylvania has over three million rural residents using private water wells for drinking water supplies but is one of the few states that lack statewide water well construction or management standards. The study described in this article aimed to determine the prevalence and causes of common health-based pollutants in water wells and evaluate the need for regulatory management along with voluntary educational programs. Water samples were collected throughout Pennsylvania by Master Well Owner Network volunteers trained by Penn State Extension. Approximately 40% of the 701 water wells sampled failed at least one health-based drinking water standard. The prevalence of most water quality problems was similar to past studies although both lead and nitrate-N were reduced over the last 20 years. The authors' study suggests that statewide water well construction standards along with routine water testing and educational programs to assist water well owners would result in improved drinking water quality for private well owners in Pennsylvania.

The influence of well construction on bacterial contamination of private water wells in Pennsylvania.

Pennsylvania has a large population that relies on private water wells, but no statewide regulations govern the location or construction of the wells. Bacterial contamination occurs in nearly half of these water supplies, representing a health risk to rural residents. The role of large-scale aquifer contamination versus wellhead contamination from poor construction is poorly understood. The authors disinfected and installed sanitary well caps on 16 wells that contained coliform bacteria and retested them after 30-60 days and one year. Coliform bacteria were present in seven of the 16 wells within 30-60 days and all but two wells within one year. The occurrence and prevalence of bacteria in wells appeared to be influenced by weather conditions during the study. The few wells where disinfection and installation of a sanitary well cap were successful had low initial coliform bacteria and no E. coli. Samples were also collected from 24 new wells that were constructed with a grout seal and sanitary well cap. Twenty-nine percent contained coliform bacteria, and 17 percent contained E. coli. The results from this limited number of wells suggest that bacterial contamination of private wells in Pennsylvania may often originate from areas away from the wellhead.