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Volatile Organic Compounds in the Nations Ground Water and Drinking-Water Supply Wells—A Summary

By Michael J. Moran, Pixie A. Hamilton, and John S. Zogorski

Introduction

Volatile organic compounds (VOCs) are produced in large volumes and are associated with a myriad of products, such as plastics, adhesives, paints, gasoline, fumigants, refrigerants, and dry-cleaning fluids. Widespread and long-term use of VOCs and their ability to persist and migrate in ground water raise questions about possible adverse effects on the environment, including drinking-water quality. A long-term investigation by the National Water-Quality Assessment (NAWQA) Program of the United States Geological Survey (USGS) provides the most comprehensive national analysis to date of the occurrence of VOCs in ground water, based on results from sampling between 1985 and 2002. Among the major findings are that VOCs were detected in most aquifers throughout the Nation, and were not limited to a few specific aquifers or regions. VOCs were not detected, however, in many of the nearly 3,500 sampled wells; for example, about 80 percent had no detections above a threshold of 0.2 part per billion. The most frequently detected VOCs were chloroform, the solvents PCE and TCE, and the gasoline oxygenate MTBE; 13 of the 55 compounds included in the assessment were not detected at all. A separate analysis of untreated ground-water samples from drinking-water supply wells showed that VOCs were detected in domestic well samples (14 percent) and public well samples (26 percent), but seldom at concentrations likely to affect human health (less than 2 percent had concentrations greater than Federal drinking-water standards). This Fact Sheet highlights selected national and regional findings on the occurrence of VOCs in ground water and in drinking-water supply wells. It serves as a companion product to a USGS Circular (1292) titled "The Quality of Our Nation's Waters—Volatile Organic Compounds in the Nation's Ground Water and Drinking-Water Supply Wells," by Zogorski and others (2006).

The PDF for the report is 182 kb

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