Collaborative Science Provides Understanding of Contaminants in Bottled Water-an Increasingly Common Alternate Drinking Water Source Active

The quality and sustainability of drinking water is a concern in the United States and globally owing to increasing water use, water reuse, and contamination of water sources. In the United States, drinking water is delivered through three main supply chains: public tap water, private tap water, and bottled water. To maintain a safe supply, select water-borne pathogens and chemical contaminants are actively regulated and monitored in U.S. public-supply tap water under the Safe Drinking Water Act and in bottled water as a food under the Food, Drugs, and Cosmetics Act, whereas private-supply tap water is not systematically regulated or monitored.  

The U.S. Geological Survey (USGS) and public health experts collaborate on a series of studies to provide improved understanding of human exposure to environmental contaminants through drinking water. The scientists have taken a strategic approach of following contaminants from sources in the environment to the point of exposure at the tap to understand human exposure. They have reported the presence of mixtures of inorganic and organic contaminants in sources of water through distribution systems and in public-supply and private-well tap water, generally at low levels not exceeding existing regulations. Comparable data are lacking on potential human exposure to contaminants through bottled water, which is an increasingly common alternate drinking water source.

Sources/Usage: Public Domain.

To address that gap in understanding, the USGS, U.S. Environmental Protection Agency (EPA), Food and Drug Administration (FDA), and National Institute of Environmental Health Science assessed inorganic, organic, and microbial contaminant mixtures in selected bottled waters available for purchase in the United States. The study analyzed 30 different bottled waters, including purified tap water and spring water from the United States, and imported, for 53 inorganics, 465 organics, and 14 microbial metrics, many of which are not routinely monitored.

This study assessed potential human health effects by comparing measured contaminant concentrations to FDA's standards of quality (SOQ) levels and to EPA's maximum contaminant level goals (MCLGs). MCLGs are health advisory levels that establish a margin-of-exposure concentration below which there is no known risk to vulnerable populations (for example, infants, children, pregnant women, elderly, and immune-compromised).

Consistent with the results of previous studies of public-supply and private-well tap water and source waters by this group, regulated and unregulated chemicals (inorganic, organic) were detected in bottled water samples. The researchers reported that 48 of the 53 inorganics and 45 of the 465 organics were detected at least once among all bottled water samples. Disinfection byproducts of chlorine disinfection, volatile organic compounds, and pesticides were the most frequently detected organic chemicals in bottled water. Arsenic, uranium, lead, and nitrate were the most frequently detected inorganic compounds. No per- and polyfluoroalkyl substances, pharmaceutical, or phthalate contaminants were detected among the samples.

None of the bottled water samples exceeded SOQs; however, precautionary health-based screening levels (MCLGs) of zero were exceeded for several inorganic contaminants including arsenic, lead, uranium, and disinfection byproducts. The MCLGs were exceeded, primarily owing to disinfection byproducts in tap-water-sourced bottled water and co-occurring inorganic and organic contaminants in spring-sourced bottled water.

The results of this study on contaminants in bottled water and previous studies on public and private point-of-use tap water demonstrate that the three supply chains for drinking water all face a similar challenge of contaminants that occur in watersheds and aquifers used for drinking water sources, contaminants that are generated during disinfection processes and distribution, and contaminants at the point of use.

Continued comprehensive studies with a broad array of public health experts (EPA, FDA, National Cancer Institute, National Institute of Allergy and Infectious Disease, National Institute of Environmental Health Science, academia, Tribal entities, water purveyors, and others) aim to contextualize the results of these studies to better understand the extent to which contaminant exposure through drinking water results in a risk to public health. 

This research was supported by the USGS Ecosystems Mission Area, Environmental Health Program.