Under the 1996 amendments to the federal Safe Drinking Water Act, the U.S. Environmental Protection Agency is required once every five years to issue a new list of up to 30 unregulated contaminants for which public water systems must monitor. The intent of this rule is to provide baseline occurrence data that the EPA can combine with toxicological research to make decisions about potential future drinking water regulations. We are currently going through the third round of this contaminant testing.
The most recent UCMR, the Third Unregulated Contaminant Monitoring Rule (UCMR3),
was signed by former EPA Administrator Lisa P. Jackson on April 16, 2012. The EPA, the states, laboratories and public water systems all participated in the testing for UCMR3 in various ways. The testing occurred between January 2013 and December 2015.