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Private wells are susceptible to contamination from flooding and are exempt from the federal requirements of the Safe Drinking Water Act. Consequently, well users must manage (e.g., disinfect) and maintain (e.g., regularly test) their own wells to ensure safe drinking water. However, well user practices and perceptions of well water quality in the years following a natural disaster are poorly characterized. An online follow-up survey was administered in October 2020 to private well users who had previously experienced Hurricane Harvey in 2017. The survey was successfully sent to 436 participants, and 69 surveys were returned (15.8% return rate). The survey results indicate that well users who had previously experienced wellhead submersion or a positive bacteria test were more likely to implement well stewardship practices (testing and disinfection) and to report the feeling that their well water was safe. While the majority of well users believed that their water was safe (77.6%), there was a significant decrease in well water being used for drinking, cooking, and for their pets after Hurricane Harvey. Generally, these well users tend to maintain their wells at higher rates than those reported in other communities, but there continues to be a critical need to provide outreach regarding well maintenance practices, especially before natural disaster events occur. [ABSTRACT FROM AUTHOR]

Microbial contamination of private well systems continues to be a prominent drinking water concern, especially for areas impacted by floodwaters. Hurricane Harvey deposited nearly 60 inches of rain, resulting in extensive flooding throughout Houston, Texas, and neighboring counties. A sampling campaign to test private wells for fecal indicator bacteria was initiated in the weeks following flooding. Escherichia coli concentrations measured in wells were utilized in a quantitative microbial risk assessment to estimate the risk of infection for both drinking water and indirect ingestion exposure scenarios. Derived reference pathogen doses indicated that norovirus (1.60 × 10−4 to 8.32 × 10−5) and Cryptosporidium (2.37–7.80 × 10−6) posed the greatest health risk via drinking, with median health risk estimates exceeding the U.S. Environmental Protection Agency's modified daily risk threshold of 1 × 10−6 for a gastrointestinal infection. Bathing (1.78 × 10−6), showering (4.32 × 10−7), and food/dish washing (1.79 × 10−6) were also identified to be exposure pathways of health concern. A post-flood microbial risk assessment of private wells in the Gulf Coast has not previously been conducted. Estimating these health risks can provide scientifically supported guidance regarding which well water practices are safest, especially when well water quality is unknown. Developing this guidance is critical as coastal communities experience increased vulnerability to flooding. [ABSTRACT FROM AUTHOR]

Gastrointestinal (GI) illness risks associated with exposure to waters impacted by human and nonhuman fecal sources were estimated using quantitative microbial risk assessment (QMRA). Microbial source tracking (MST) results had identified Escherichia coli (E. coli) contributors to the waterbody as human and unidentified (10%), cattle and domestic animals (25%), and wildlife (65%) in a rural watershed. The illness risks associated with ingestion during recreation were calculated by assigning reference pathogens for each contributing source and using pathogen dose–response relationships. The risk of GI illness was calculated for a specific sampling site with a geometric mean of E. coli of 163 colony forming units (cfu) 100 mL−1, and the recreational standard of E. coli, 126 cfu 100 mL−1. While the most frequent sources of fecal indicator bacteria at the sampling site were nonhuman, the risk of illness from norovirus, the reference pathogen representing human waste, contributed the greatest risk to human health. This study serves as a preliminary review regarding the potential for incorporating results from library-dependent MST to inform a QMRA for recreational waters. The simulations indicated that identifying the sources contributing to the bacterial impairment is critical to estimate the human health risk associated with recreation in a waterbody. [ABSTRACT FROM AUTHOR]