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How frequently are volatile organic compounds (VOCs) detected in groundwater?

Volatile organic compounds (VOCs) are chemicals used to make everyday products, including refrigerants, plastics, adhesives, paints, and petroleum products. USGS has monitored VOCs and other groundwater contaminants since the late 1980s. 

VOCs can get into groundwater through spills, leaks, or through improper waste disposal. They are most often found in shallow groundwater beneath urban areas. 

  • The VOCs detected most often are trihalomethanes, solvents, and petroleum hydrocarbons. Trihalomethanes are chemicals that include byproducts from water chlorination.
  • VOCs detected less frequently include chemicals used in manufacturing organic chemicals, gasoline oxygenates, fumigants, and refrigerants.

VOCSs found in shallow monitoring wells in urban areas often occur as mixtures of two or more compounds. Although VOCs were detected in some public-supply wells, relatively few individual VOCs or VOC mixtures were found at concentrations that approached or exceeded human-health benchmarks.

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Updated Date: July 22, 2026
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