Third Unregulated Contaminant Monitoring Rule (UCMR3)

glass water against sky smallUCMR3, which was signed into effect on April 16, 2012, is the third round of contaminant testing mandated by a 1996 amendment to the federal Safe Drinking Water Act. Once every five years, the EPA issues a list of up to 30 unregulated contaminants and requires all public water systems serving more than 10,000 people, as well as 800 representative public water supplies serving 10,000 or fewer and 800 public water supplies serving 1,000 or fewer, to monitor them.

The UCMR3 contaminants requiring monitoring are as follows:

Seven Volatile Organic Compounds
– trichloropropane
– butadiene
– chloromethane (methyl chloride)
– dichloroethane
– bromomethane (methyl bromide)
– chlorodifluoromethane (HCFC-22)
– bromochloromethane (halon 1011)

One Synthetic Organic Compound
– dioxane

Six Metals
– vanadium
– molybdenum
– cobalt
– strontium
– chromium
– chromium 6 (hexavalent chromium)

One Oxyhalide Anion
– chlorate

UCMR3 testing occurs between January 2013 and December 2015 and helps to determine the geographic prevalence and levels of these contaminants throughout the country. This information, combined with toxicological data, provides baseline data that the EPA uses to determine the necessity of future drinking water regulations.

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