Monday, May 16, 2016

Private Wells and Health Risks in Your Drinking Water

Private wells do not fall under the regulatory authority of the U.S. Environmental Protection Agency (EPA) or the Safe Drinking Water Act. In the past it was always assumed that groundwater that supplies private wells is fairly safe and clean. However, recent research by the U.S. Geological Survey and studies of water borne disease outbreaks associated with untreated groundwater have found that private wells, springs and cisterns are a potential source of elevated health risk. In addition, while waterborne disease outbreaks overall have fallen since 1971, the waterborne disease outbreaks in private well systems continues to increase relative to public systems.
This is of concern because according to the EPA, approximately 15% of U.S. households, more than 47 million people get their drinking water from private wells and springs.

Preliminary efforts to survey water quality in private systems in limited studies in Pennsylvania, Wisconsin and Virginia report that 23−58% of wells tested in their studies exceed at least one safe drinking water act health-based standard. However, since 2010 Virginia has been operating the subsidized well water testing clinics as part of the Virginia Household Water Quality Program testing wells throughout Virgininia. The goal of the Virginia Household Water Quality Program is to educate well owners, improve the water quality and protect the health of Virginians with private water supplies, such as wells, springs and cisterns. In 60 of Virginia’s 95 counties more than half the households rely on private wells, springs, and cisterns. In total there are more than 1,500,000 households in Virginia with private water supplies.

The Virginia Cooperative Extension obtained a grant from the U.S. Department of Agriculture’s Cooperative Research Education and Extension Service to restart the Virginia Household Water Quality Program originally launched in 1989. Working with the researchers at Virginia Tech the program has used the data they have collected to identify characteristics in wells within counties and throughout the Commonwealth. In the 2012 clinics analysis for lead and copper were added. Participation in the drinking water clinics is voluntary and though the analysis is subsidized, participants are still charged a fee, currently $55. Homeowners who wish to participate have to hear about the clinic, show up for two meetings, purchase a water sampling kit with instructions and are asked to fill out a questionnaire about system characteristics, perceived water quality and household demographics and drop off their samples on time on the scheduled day. Typically, better educated and more affluent households participate.

The scientists at Virginia Tech have used the data from the 2012 clinics and targeted additional field study to examine, lead in drinking water from private wells. The following information is from their recent paper cited below.
Of the 2,146 samples taken in an 18 month period from spring 2012 to fall 2013, 58% of the wells sampled exceeded at least one Maximum Contaminant Level (MCL) from the EPA’s safe drinking water act’s levels though only 14 of the 82 parameters were tested. Bacterial contamination was the most common issue, with 46% of systems testing positive for total coliforms with 10% having E. coli present. The most common treatment systems were water softeners which are used to treat hard water, elevated iron and manganese which were found to be less prevalent that water softener sales would indicate.

Using the action level for lead and copper as a threshold, 19% of the tested systems had elevated lead concentrations (15 μg/L) and 12% had elevated copper concentrations (1.3 mg/L) in the first draw. Lead leaches into water primarily as a result of corrosion of plumbing and well components. Corrosion control techniques such as adjusting pH or alkalinity that are commonly used in public systems are not common in private wells where the decision to install and maintain treatment is solely the prerogative and responsibility of the homeowner. As a result, though 26% of the private wells had pH outside the neutral range of 6.5-8.5 (and 89% of these were below 6.5), only 5% of private well systems had acid neutralizers installed to control pH and corrosion within the home and 3% had reverse osmosis units that could remove lead among other contaminants. 

The scientists did not find a correlation between self-reported well depths and lead concentrations, but lead concentrations were negatively correlated with pH values. The lower the pH (more acidic the water) the higher the lead concentrations found. Houses built before 1988 when the ban on lead went into effect had higher lead concentrations; however, it is important to note that elevated lead concentrations were still found in homes built after 1988. The scientists attributed this to the presence of lead in brass fixtures and faucets. If that is correct, then with the ban on lead containing materials in the Reduction of Lead in Drinking Water Act, lead release from brass components should be reduced in the future.

For most of the private well supplied systems sampled in this study, flushing for 5 minutes reduced lead concentrations below 15 μg/L. However, 2% of households experienced an increase in lead concentrations with flushing suggesting that there may be other components within the well and plumbing system that release lead and/or particulate lead and may have been mobilized. To develop effective remediation and prevention additional work must be done to increase our understanding of the mechanisms of lead release in well systems. Brass fittings and components within the well might be the source of soluble or particulate lead.

Pieper, Kelsey J.; Krometis, Leigh-Anne H. ; Gallagher Daniel L; Berham, Brian L.; and Edwards, Marc; Incidence of waterborne lead in private drinking water systems in Virginia; Journal of Water and Health; 13.3 2015. Pages 897-907.

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