The 1996 amendments to the Safe Drinking Water Act (SDWA) require that EPA establish criteria for a program to monitor unregulated contaminants and identify no more than 30 contaminants to be monitored every five years. EPA identified and published unregulated contaminants for the first direct-implementation of the Unregulated Contaminant Monitoring Rule (i.e., UCMR 1) and a revised approach for monitoring in the Federal Register dated September 1999. UCMR 1 established a tiered monitoring approach, and required all public water systems (PWSs) serving more than 10,000 people and a representative sample of PWSs serving 10,000 or fewer people to monitor for unregulated contaminants from 2001-2005. The second rule, UCMR 2, required PWSs to monitor during a 12-month period from 2008-2010.
As proposed, UCMR 3 would require public water systems (PWSs) to monitor for 28 chemicals and two viruses (see link for additional information). All PWSs serving more than 10,000 people, and a representative sample of 800 PWSs serving 10,000 or fewer people, would be required to conduct Assessment Monitoring for 28 "List 1" chemicals during a continuous 12-month period from January 2013 through December 2015. In addition, a targeted group of 800 PWSs serving 1,000 or fewer people would be required to conduct Pre-Screen Testing for two "List 3" viruses during a 12-month period from January 2013 though December 2015.
For more information about the UCMR-3 program go to: http://water.epa.gov/lawsregs/rulesregs/sdwa/ucmr/ucmr3/basicinformation.cfm