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Water: Unregulated Contaminant Monitoring Rule 3

Basic Information about the Unregulated Contaminant Monitoring Rule 3 (UCMR 3)

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Sampling for the third Unregulated Contaminant Monitoring Regulation (UCMR 3) will occur from 2013-2015. The monitoring includes 30 contaminants (28 chemicals and 2 viruses).

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The 1996 Safe Drinking Water Act (SDWA) amendments require that once every five years EPA issue a new list of no more than 30 unregulated contaminants to be monitored by public water systems (PWSs). The first Unregulated Contaminant Monitoring Rule (UCMR 1) was published on September 17, 1999, the second (UCMR 2) was published on January 4, 2007 and the third (UCMR 3) was published on May 2, 2012. This monitoring provides a basis for future regulatory actions to protect public health.

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About this rule
UCMR 3 requires public water systems (PWSs) to monitor for 30 contaminants (28 chemicals and two viruses) under each of the three lists:

  • Assessment Monitoring (List 1 Contaminants) uses common analytical method technologies used by drinking water laboratories. For UCMR 3, all PWSs serving more than 10,000 people and 800 representative PWSs serving 10,000 or fewer people will monitor for 21 List 1 contaminants during a 12-month period from January 2013 through December 2015.

  • Screening Survey (List 2 Contaminants) monitoring uses specialized analytical method technologies not as commonly used by drinking water laboratories. All PWSs serving more than 100,000 people, 320 representative PWSs serving 10,001 to100,000 people and 480 representative PWSs serving 10,000 or fewer people are required to monitor for 7 List 2 contaminants during a 12-month period from January 2013 through December 2015.

  • Pre-Screen Testing (List 3 Contaminants) uses newer method technologies not as commonly used by drinking water laboratories. For UCMR 3, EPA will select 800 representative PWSs serving 1,000 or fewer people that do not disinfect. These PWSs with wells that are located in areas of karst or fractured bedrock, will participate in monitoring for two List 3 viruses during a 12-month period from January 2013 through December 2015.

EPA will pay for the analysis of all samples from systems serving 10,000 or fewer people and will arrange for the collection of samples from the systems that participate in the Pre-Screen Testing.

UCMR 3 Contaminants and Corresponding Analytical Methods

Assessment Monitoring (List 1 Contaminants)
Contaminant Analytical Methods Exit EPA Disclaimer
Volatile Organic Compounds EPA 524.3
chloromethane (methyl chloride)
bromomethane (methyl bromide)
chlorodifluoromethane (HCFC-22)
bromochloromethane (halon 1011)
Synthetic Organic Compounds EPA 522
Metals EPA 200.8 Rev 5.4, ASTM D5673-10, Standard Methods 3125 (1997) (excluding chromium-6)
chromium *
chromium-6 EPA 218.7
Oxyhalide Anion EPA 300.1, ASTM D6581-08, Standard Methods 4110D (1997)
Perfluorinated Compounds EPA 537 Rev 1.1
perfluorooctanesulfonate acid (PFOS)
perfluorooctanoic acid (PFOA)
perfluorononanoic acid (PFNA)
perfluorohexanesulfonic acid (PFHxS)
perfluoroheptanoic acid (PFHpA)
perfluorobutanesulfonic acid (PFBS)

* Monitoring for total chromium – in conjunction with UCMR 3 Assessment Monitoring – is required under the authority provided in Section 1445(a)(1)(A) of SDWA.

About this rule

Screening Survey (List 2 Contaminants)
Contaminant Analytical Methods
Hormones EPA 539
17-α-ethynylestradiol (ethinyl estradiol)
16-α-hydroxyestradiol (estriol)

About this rule

Pre-Screen Testing (List 3 Contaminants)
Contaminant Analytical Methods
Viruses EPA 1615

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Why was the UCMR program developed?
The UCMR program was developed in coordination with the Contaminant Candidate List (CCL). The CCL is a list of contaminants that are not regulated by the National Primary Drinking Water Regulations, are known or anticipated to occur at public water systems and may warrant regulation under the Safe Drinking Water Act. Data collected through UCMR are stored in the National Contaminant Occurrence Database (NCOD) to support analysis and review of contaminant occurrence, to guide the CCL selection process and to support the Administrator's determination of whether to regulate a contaminant in the interest of protecting public health.

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How did EPA select these contaminants?
EPA reviewed contaminants that had been targeted through existing prioritization processes, including previous UCMR contaminants and the Contaminant Candidate List (CCL). Additional contaminants were identified based on current research on occurrence and health effect risk factors. Pesticides that were not registered for use in the United States, contaminants that did not have an analytical reference standard and contaminants whose analytical methods were not ready for use were removed from the list. EPA further prioritized the remaining contaminants based on more extensive health effects evaluations by the Office of Water’s Office of Science and Technology. These procedures for evaluating health effects were developed to support the ranking of contaminants for future CCLs.

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What are the environmental and public health benefits?
UCMR benefits the environment and public health by providing EPA and other interested parties with scientifically valid data on the occurrence of these contaminants in drinking water, permitting assessment of the population being exposed and the levels of exposure. This data set is one of the primary sources of occurrence and exposure information the Agency uses to develop regulatory decisions for emerging contaminants.

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What are the major differences between UCMR 2 and 3?
UCMR 3 builds on the established structure of UCMR 1 and 2, and makes minor changes to improve the rule design. Per the cyclical nature of UCMR, a new list of contaminants and analytical methods are defined. UCMR 3 reflects lessons learned from UCMR 2 and:

  • Redefines applicability to include PWSs that purchase all of their water.
  • Clarifies the terms of representative ground water sampling.
  • Updates the reporting elements (including adding a data element for zip codes for the customers served by PWSs).

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What is the EPA Laboratory Approval Program for UCMR 3?
Laboratories interested in analyzing samples for PWSs subject to the UCMR 3 monitoring requirements will need to register for the EPA Laboratory Approval Program. Interested laboratories can complete and submit method-specific application packages. Following EPA’s review, qualified laboratories will become eligible to participate in a proficiency testing (PT) program. Laboratories successfully completing the PT analyses will be granted method-specific approval. UCMR 3 requires laboratories have EPA approval to analyze PWS samples.

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