EPA 815-F-10-004

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Announcement of Proposed Rule: Revisions to 

the Unregulated Contaminant Monitoring 

Regulation (UCMR) for Public Water Systems

Summary

EPA proposes the design for the third Unregulated Contaminant Monitoring Regulation (UCMR 

3). This design includes monitoring for 28 chemicals and two viruses, for a total of 30 UCMR 3 

contaminants using seven EPA analytical methods and/or four equivalent consensus 

organization-developed methods. 

Background

The 1996 amendments to the Safe Drinking Water Act (SDWA) require that EPA identify a new 

list of unregulated drinking water contaminants every five years. This list must not exceed 30 

contaminants for public water system (PWS) monitoring. The data set collected through UCMR 

informs EPA on the occurrence and public exposure to support determinations of whether to 

establish a health based standard to protect public health. The first Unregulated Contaminant 

Monitoring Regulation (UCMR 1) was published on September 17, 1999, and the second 

(UCMR 2) was published on January 4, 2007. EPA anticipates that the final UCMR 3 will be 

published in early 2012.

About this regulation

As proposed, UCMR 3 revises the previous rule (UCMR 2) as follows: 

• identifies a new list of contaminants to be monitored;

• lists the analytical methods to be used; 

• specifies the number of systems required to monitor and where they are required to 

monitor (e.g., entry point to the distribution system and, for some contaminants, in the 

distribution system); and

• makes minor modifications to the requirements based on previous experience 

implementing UCMR 1 and UCMR 2. 

All PWSs serving more than 10,000 people (i.e., large systems) and 800 representative PWSs 

serving 10,000 or fewer people (i.e., small systems) would monitor for the chemicals from 2013 

through 2015. A representative selection of 800 undisinfected ground water PWSs serving 1,000 

or fewer people would monitor for the viruses from 2013 through 2015. 

PWSs that monitor for chemicals would sample at their entry point to the distribution system 

(EPTDS). Additionally, monitoring for chlorate and the four metals – cobalt, molybdenum, 

vanadium and strontium – would take place at one distribution system sampling point per 

treatment plant. EPA contractors would collect samples at each EPTDS location for PWSs 

selected for virus monitoring due to the complexity of the sampling techniques. Virus monitoring 

also includes the following pathogen indicators: total coliform, E. coli, bacteriophage, 

Enterococci and aerobic spores. 
EPA 815-F-10-004

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PWSs with surface water or “ground water under the direct influence of surface water” would 

monitor four times during their year of monitoring. PWSs with ground water would monitor

twice during their year of monitoring. 

How did EPA select these contaminants?

EPA identified and selected the contaminants for UCMR 3 through a prioritization process. The 

Agency first reviewed the Contaminant Candidate List (CCL 3) and the “pre-CCL.” Under the 

CCL 3 process, EPA evaluated 7,500 unregulated contaminants in the development of the final 

CCL 3. The final CCL 3 is comprised of 104 chemicals or chemical groups, and 12

microbiological contaminants. This list outlines unregulated contaminants with the greatest 

potential to occur at PWSs, and which may require regulation due to the potential for human 

health concerns.

EPA then reviewed additional sources of information about emerging contaminants of concern, 

and expanded the list to approximately 150 potential UCMR 3 contaminants. That list of 150 

contaminants was then narrowed by eliminating contaminants for which analytical methods 

would not be ready in time for UCMR 3 monitoring. An EPA and state working group further 

considered this narrowed list and used health effects data and information regarding other critical 

endpoints to arrive at the proposed list of 30 UCMR 3 analytes described in Exhibit 1. The 

proposed rule also invites public comment on whether hexavalent chromium (“chromium-6”) -

and possibly total chromium - should be included in UCMR 3 in lieu of any of the 30 

contaminants in Exhibit 1.
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Exhibit 1: Proposed Contaminants

Chemical Monitoring

17-β-estradiol chlorodifluoromethane (HCFC-22)

17-α-ethynylestradiol (ethinyl estradiol) bromochloromethane (Halon 1011)

estriol 1,4-dioxane

equilin vanadium

estrone molybdenum

testosterone cobalt

4-androstene-3,17-dione strontium

1,2,3-trichloropropane chlorate

1,3-butadiene perfluorooctanesulfonic acid (PFOS) 

chloromethane (methyl chloride) perfluorooctanoic acid (PFOA)

1,1-dichloroethane perfluorononanoic acid (PFNA) 

n-propylbenzene perfluorohexanesulfonic acid (PFHxS) 

bromomethane (methyl bromide) perfluoroheptanoic acid (PFHpA) 

sec-butylbenzene perfluorobutanesulfonic acid (PFBS)

Virus Monitoring

enteroviruses noroviruses

What are the major differences between UCMR 2 and 3?

In addition to the new list of 30 contaminants to be monitored, proposed changes between 

UCMR 2 and UCMR 3 include the following: revising monitoring requirements (which would

be now based on retail population); revising reporting schedules; revising data elements to be 

reported; and adding Pre-Screen Testing for two viruses. 

What are the environmental and public health benefits?

The UCMR 3 program provides EPA and other interested parties with scientific data on the 

occurrence of targeted contaminants in drinking water, the number of people potentially being 

exposed, and an estimate of the levels of that exposure. UCMR information is the primary source 

of occurrence and exposure data for the Agency to determine whether to regulate these 

contaminants.
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What is the cost of the regulation?

Non-labor costs would be incurred primarily by EPA and large PWSs. They include the cost of 

shipping samples to laboratories, and the cost of laboratory analyses. The cost of the analyses for 

chemical monitoring is estimated at $1,320 per sample set. The cost of the analyses for virus 

monitoring is estimated at $1,650 per sample set. Laboratory analysis and sample shipping 

account for approximately 86 percent of the national cost for UCMR 3 implementation.

PWSs, states and EPA would also have labor costs. Other labor costs for PWSs, states and EPA 

include: activities such as notifying PWSs selected to participate, collecting samples, reviewing 

data, reporting, and keeping records. EPA expects that states would only incur labor costs 

associated with their voluntary assistance with UCMR 3 implementation. Since state 

participation is voluntary, the levels of effort and labor costs would vary depending on each 

state’s agreement with EPA. State costs for UCMR 3 were estimated using the State Resource 

Model that was developed by the Association of State Drinking Water Administrators in 

conjunction with EPA. For the model estimates of state costs, the levels of state participation in 

UCMR 3 were input as the same levels observed in UCMR 2.

The average annual costs for small water systems complying with this rule are minimal. EPA 

specifically structured the rule to avoid significantly affecting small entities by assuming all 

costs for laboratory analyses, shipping, and quality control for small entities. Small systems 

monitoring for chemicals would only incur labor costs, which are attributed to the additional 

labor required for reading about their requirements, monitoring, reporting, and record keeping.

Small systems monitoring for viruses would incur even lower labor costs since EPA contractors 

will collect the samples, and record and report the data. 

EPA estimates that nationwide, the average annual cost of UCMR 3, across the five-year cycle of 

2012-2016, is approximately $15 million.

How can I get additional information?

For general information on UCMR 3, please visit the UCMR 3 website at:

http://water.epa.gov/lawsregs/rulesregs/sdwa/ucmr/ucmr3/index.cfm or contact the Safe 

Drinking Water Hotline at (800) 426-4791 (open Monday - Friday, excluding legal holidays, 

from 10:00 a.m. to 4:00 p.m. Eastern Time). The Safe Drinking Water Hotline may also be found 

on the Internet at: http://water.epa.gov/aboutow/ogwdw/hotline/index.cfm.