A review of perchlorate occurrence in public drinking water systems

The national occurrence of perchlorate in drinking water was analyzed and mapped by compiling data from existing perchlorate occurrence surveys. The existing surveys included studies conducted by utilities for the first Unregulated Contaminant Monitoring Rule and by the states of Arizona, California, Massachusetts, and Texas. Perchlorate was detected in 26 states, Puerto Rico, and the Mariana Islands and was found in at least one source of approximately 5% of the nation—s large (> 10,000 population) public water systems. When found, perchlorate was typically present at concentrations of < 12 μg/L. Some water utilities that detected perchlorate have discontinued the use of perchlorate‐contaminated sources. On the basis of the results of a 2007 phone survey, it is estimated that at least 50 mgd of potable water production has been taken off line as a result of perchlorate contamination.