Occurrence of perchlorate IN DRINKING WATER SOURCES

Abstract

Perchlorate is of concern to drinking water suppliers because of its potential risk to human health, tendency to disperse rapidly in groundwater, and resistance to conventional water treatment processes. An occurrence survey was performed in 1997 and 1998 to assess the prevalence of perchlorate in surface and subsurface drinking water supplies of the American Water System. The survey examined 40 surface water sites in 11 states and 367 groundwater wells in 17 states. No perchlorate was detected in any of the surface waters. The presence of perchlorate was confirmed in nine (~2.5%) wells, all located in California or New Mexico. Positive perchlorate concentrations ranged from < 4 to ~7 μg/L, well below the health advisory guideline value of 18 μg/L suggested by the California Department of Health Services. These results help confirm previous reports that perchlorate contamination is a localized problem affecting sites near military‐related facilities or other major sources of perchlorate.