Reliable access to safe and affordable drinking water is essential for maintaining human health, hygiene, food preparation, and dignity more broadly (UNDP, 2006). Consumption of microbiologically contaminated drinking water is associated with a substantial burden of disease globally (Lim et al., 2016; Benedict et al., 2017; Khalil et al., 2018; Prüss-Ustün et al., 2019; Greco et al., 2019). Chronic exposures to heavy metals, disinfection byproducts, and other chemical contaminants in drinking water are also known to cause or contribute to bladder, colon, kidney, liver, pancreas, rectal, and stomach cancers, as well as coronary heart disease, hypertension, and stroke (Kuo et al., 2017; Moon et al., 2017; Chowdhury et al., 2018; DCEG, 2022).

In 2010, the United Nations recognized the human right to safe drinking water, as did the United States (US) state of California, in 2012 (UN Economic and Social Council, 2002; UN, 2010, 2014; CAWB, 2022). However, in the US, the right to safe drinking water is unevenly realized, and many lower-income, minority, and rural populations in the US have limited or unreliable access to safe drinking water (Sultana et al., 2012; McDonald and Jones, 2018; Meehan et al., 2020; Mueller and Gasteyer, 2021). In rural areas of the US overall, an estimated ∼1.8 million people lack reliable access to safe drinking water in their homes (estimate derived from data [Annex 3] in a recent United Nations report) (WHO/UNICEF, 2019). For those with access to utility-supplied water, rates of health-based violations of EPA drinking water regulations are highest in lower-income rural areas overall; and Central Appalachia is one of five regional clusters with the highest rates of violations as well as reported incomplete plumbing (i.e., no hot and cold running water or a functioning sink, bath, or shower) (Allaire et al., 2018; Mueller and Gasteyer, 2021). Most rural households without utility-supplied water have access to private wells (not regulated by the EPA), but we lack comprehensive data on private well water quality and associated health impacts in the US (Lee et al., 2023).

The Appalachian Region, as defined by the Appalachian Regional Commission (a federal agency established in 1965), is home to ∼26.1 million people across 423 counties in 13 states (AL, GA, KY, MD, MS, NY, NC, OH, PA, SC, TN, VA, WV); the Central Appalachia subregion consists of 82 counties in the states of KY, TN, VA, and WV (ARC, 2022). In addition to documented disparities in safe water access (Mueller and Gasteyer, 2021), the Appalachian region is impacted by substantial disparities in health outcomes. These health disparities include higher mortality rates for 7 of the 10 leading causes of death in the US, and higher rates of cardiopulmonary disease and cancer are particularly acute in Central Appalachia (ARC, 2017; Behringer and Friedell, 2006; Krometis et al., 2017; McGarvey et al., 2011; Meit et al., 2017; Pollard and Jacobsen, 2022).

Although there is evidence of disparities in safe water access across the Appalachian Region, our understanding of which subregions, communities, and populations in Appalachia may have higher risks of exposure to contaminated drinking water is severely limited (Cohen et al., 2020, 2022; Krometis et al., 2017). Our understanding of associated health outcomes is more limited still. By way of example, a recent (382 page) report on “Health Disparities in Appalachia” did not address water, sanitation, or enteric diseases (ARC, 2017).

Our recent systematic review and meta-analysis study, focused on water and health studies conducted from 2000 to 2020 in Appalachia, further demonstrated the relatively limited nature of water-and-health focused research for this region of the US (Cohen et al., 2020; Darling et al., 2023). Of 85 eligible studies identified, 32% (n = 27) assessed potentially water-related health outcomes, though only 4.7% of studies overall (n = 4) used case-control or cohort designs, the rest using cross-sectional designs (Darling et al., 2023). Only five studies reported outcome data for gastrointestinal illness, and overall only 6% of the studies (n = 5) were conducted exclusively in the Central Appalachia region (Darling et al., 2023). In addition to limited evidence from the studies identified in our review, in 2021 our group conducted a small study (9 households, 18 individuals) in Wise County, VA (part of Central Appalachia), collecting water samples and survey data from a small rural community of households all with private well water. In water samples from 33% (n = 3) of these homes we detected E. coli (an indicator of fecal contamination), specific enteric pathogens (e.g., Campylobacter), and relatively high concentrations of iron and nitrate (NO3−N) (Cohen et al., 2022). Although our sample size was small, findings suggested that many lower-income rural households on well water in this region may be exposed to a variety of drinking water contaminants, and that many households in such settings may rely on bottled water as their primary drinking water source.

Considering the relative lack of water and health related data for most rural areas of Appalachia, our primary objectives for this study were to assess public and private drinking water sources, their use, quality-related perceptions, and to assess exposures to drinking water contaminants and potentially associated risk factors and health outcomes for individuals living in lower-income households in predominately rural counties in Central Appalachia. Given these objectives, in addition to collecting and analyzing drinking water samples and potentially associated individual-level reported health outcome data, we also sought to collect saliva samples to analyze antibody responses as biomarkers of previous infections with waterborne pathogens (Egorov et al., 2010; Moe et al., 2004; O'Farrell et al., 1997). Saliva is simple and non-invasive to collect, and has been used in studies to characterize potential infections with waterborne and environmentally transmitted pathogens (Egorov et al., 2018, 2021; Wade et al., 2018, 2019). As far as we are aware, ours would be the first such study to use saliva, water, and survey data to assess exposure risks to waterborne pathogens in Central Appalachia.