Vulnerability of drinking water supply wells to VOCs

A national study analyzed untreated water samples from similar to 1,100 public and 2,400 domestic wells for 55 volatile organic compounds (VOCs) and found that supplies from public wells were more vulnerable to VOC contamination than those from domestic wells. Analyses of ancillary data identified natural and anthropogenic variables associated with occurrence of the most frequently detected VOCs in public well samples. Perchloroethene and trichloroethene in public well water was associated with point sources and pumping rates, whereas trihalomethanes and the oxygenate methyl tertiary butyl ether were not associated with pumping rates and had a nonpoint source signature. Study findings should increase awareness of the risks posed by VOC contamination of drinking water supply wells and reaffirm the need for comprehensive wellhead protection programs. VOC contamination of public well supplies can be minimized by effective management practices such as well permitting and land use planning, construction considerations such as well depth, and operational factors such as pumping rate.