Twenty-six unregulated contaminants will be monitored by U.S. drinking water suppliers under a new rule proposed by the U.S. Environmental Protection Agency. This second cycle of the Unregulated Contaminant Monitoring Rule (UCMR 2) also proposes the use of nine analytical methods to detect the contaminants.

The data collected will help the EPA determine whether to regulate the contaminants, their occurrence in drinking water, the potential population exposed to each, and the levels of exposure. The EPA currently has regulations for more than 90 contaminants. The Safe Drinking Water Act requires the EPA to identify up to 30 contaminants for monitoring every five years. The first cycle, UCMR 1, published in 1999, covered 25 chemicals and one microorganism.

All public water systems serving more than 10,000 people and a sample of 800 systems serving 10,000 people or fewer will monitor the contaminants for a 12-month period from July 2007 to June 2010. Additionally, 322 systems serving more than 100,000 people and 800 serving 100,000 or fewer will conduct the screening surveys during a 12-month period from July 2007 through June 2009.

Costs for the five-year UCMR 2 will total approximately $42.1 million. The EPA will conduct and pay for the monitoring for those water systems serving 10,000 people or fewer at a cost of $8.05 million. For more information, visit