Evaluation of private well contaminants in an underserved North Carolina community

Abstract

On-site sewage treatment systems can be an important source of antibiotic resistant bacteria and organic micropollutants into adjacent groundwater. Due to the frequent proximity of private wells to septic systems, this contamination is a concern to communities that do not have access to public municipal services. In both rural and urban environments, low-income communities, indigenous communities and those of color are disproportionately affected by well contamination. The objective of this study was to assess well water quality in an underserved North Carolina community by performing a comprehensive evaluation of microbial and organic micropollutant occurrence and determining possible sources of contamination. Well water, septic tanks, and adjacent municipal water were sampled. Culture- and molecular biology-based microbial analysis and non-targeted, high resolution mass spectrometry chemical analysis were conducted to assess water quality in comparison to nearby municipal water. Three of thirteen homes had between 1 and 6.3 CFUs/100 mL of E. coli and two homes had fecal bacteria resistant to antibiotics in their well water. The water of four homes showed concentrations of the artificial sweetener sucralose, a wastewater tracer, higher than the municipal water (range ~ 60-1500 ng L^-1). The human-specific HF183 fecal marker was detected in 79% of the wells tested. The presence of pharmaceuticals and personal care products in four home wells, along with the presence of pesticides and insecticides in two homes, suggest possible contamination from septic tanks and lawn care runoff. The implications of this work highlight the necessity of wider scale contaminant evaluation of well water.

Keywords: Antibiotic resistance; Contaminant source tracking; Emerging organic contaminants; Environmental justice; Water quality.