SEPA
United States
Environmental Protection
Agency
T
his fact sheet describes the Unregulated Contaminant Monitoring Regulation (UCMR).
It provides information for water systems and consumers.
What Is the Unregulated Contaminant Monitoring Regulation?
UCMR is a tool for the U.S. Environmental Protection Agency (EPA) to find unregulated
contaminants of concern in the nation's drinking water. The Safe Drinking Water Act gives
EPA the responsibility to protect public health and to set minimum standards for drinking water.
To do this, EPA identifies contaminants that might be harmful to human health. (A contaminant
is any physical, chemical, biological, or radiological substance or matter in water.) EPA then
determines whether to set drinking water standards for individual contaminants or to require
water providers to use certain treatment processes to reduce or eliminate contaminants in the
drinking water.
As a part of this process, EPA works with local water systems to periodically test the water that
is delivered to consumers' homes for contaminants that are not regulated. This helps EPA to
know whether these contaminants occur often enough and at high enough levels to warrant
further attention. This testing takes place as part of the Unregulated Contaminant Monitoring
Regulation, or UCMR. EPA is currently implementing the second cycle of UCMR testing (with
monitoring taking place from 2008-2010), called UCMR2.
Which Water Systems Participate in UCMR2?
EPA requires all public water systems serving more than 10,000 people to participate. EPA
also requires some smaller systems serving 10,000 people or fewer to participate. EPA selects
smaller systems based on factors such as the number of people they serve, where they are
located, and whether they use water from a source such as a river or a well. Together, these
water systems gather the information EPA needs to determine if and how often these
contaminants occur in drinking water. Almost 5,000 systems are participating in UCMR2.
What Contaminants Are Systems Looking for as Part of UCMR2?
EPA considered more than 200 contaminants for further testing and selected 25 that it considers
most important. (EPA can select up to 30 contaminants every five years.) The contaminants were
selected for three main reasons:
• EPA believes that they are likely to occur in drinking water.
• They could be harmful.
• There are testing methods to look for them in drinking water.
EPA divided the 25 contaminants into two lists. The 10 "List 1" (Assessment Monitoring)
contaminants are monitored using testing methods that are more widely used. They include flame
retardants (materials that stop fires from spreading), contaminants used in explosives, and
contaminants related to insecticides. The 15 "List 2" (Screening Survey) contaminants are
monitored using testing methods that are relatively new. They include nitrosamines (chemical
compounds that exist in sources of drinking water or that form when disinfectants are added to
water to kill microbes), herbicides (used to kill unwanted plants), and herbicide degradate (formed
when herbicides change in the natural environment).
Spotlight on
NDMA and Other
Nitrosamines
Nitrosamines are
chemical compounds
that can be present in
water. NDMA is
among the more
studied of the six
nitrosamines being
monitored as a part
ofUCMR2.
EPA is currently
evaluating the health
effects of
nitrosamines.
Nitrosamines can
exist in sources of
drinking water or can
form when
disinfectants are
added to water to kill
microbes. As a part
ofUCMR2,
thousands of water
systems are
collecting information
on how often
nitrosamines occur in
drinking water.
This UCMR2 testing
will give EPA
information on how
often and at what
levels nitrosamines
occur in drinking
water. EPA will use
the UCMR2 results,
along with health
effects and other
information, to
determine whether
nitrosamines warrant
further attention.
-------
UCMR and the
Contaminant
Candidate List
UCMR is closely
coordinated with EPA's
Contaminant Candidate List,
or CCL. EPA uses both of
these programs to identify
drinking water contaminants
of concern. Both programs
focus on contaminants that
are not currently regulated.
EPA uses the best available
information to decide which
contaminants should be on
the CCL, selecting
unregulated contaminants of
highest interest to EPA for
further review. The CCL lists
contaminants that may harm
health, may occur in public
water systems, and may
require drinking water
regulation. Some of the CCL
contaminants require further
research. This could include
research on the following:
What contaminants are in
water and how often they
occur.
What methods are
appropriate to detect
contaminants.
How contaminants affect
health.
How to remove
contaminants from water.
EPA uses the CCL as its
primary source from which
to select UCMR
contaminants. Priority is
given to contaminants
where testing methods are
available and where little is
known about how often the
contaminant occurs in
drinking water.
UCMR results can also
inform CCL priorities if
UCMR contaminants are
detected in drinking water,
and if these contaminants
are not on a current CCL.
What Does UCMR2 Participation Involve? What Does It Cost?
Participating systems collect samples of drinking water and have them tested for
UCMR contaminants. The largest water systems (serving more than 100,000 people)
are testing for all 25 UCMR2 contaminants. Water systems serving 10,001 to 100,000
people are testing for all 10 contaminants on List 1. Some of these systems are also
testing for the additional 15 contaminants on List 2. Selected small water systems
(serving 10,000 or fewer people) are testing for either List 1 or List 2 contaminants (but
not both). Large systems are paying their own testing costs ($190-$370 per sample, per
testing method, on average). EPA is paying the testing costs for small systems and
managing the analysis of small system samples.
What Will EPA Do With This Occurrence Information?
EPA will use this information on what contaminants are occurring in drinking water to
help decide which contaminants might need to be regulated. When deciding to regulate
a contaminant, EPA is required to consider the following:
• Whether the contaminant has the potential to harm human health.
• How often the contaminant occurs in public drinking water.
• Whether regulation presents a meaningful opportunity to reduce public health risks.
As a part of this process, EPA evaluates whether contaminants are occurring at levels
that could harm humans. UCMR data help EPA to make this decision by providing
information on how often, and at what levels, contaminants occur in drinking water.
What Does This Information Mean to Me?
Contaminant monitoring is part of a larger process that EPA, States, Tribes, water
systems, and other partners use to protect drinking water. Health information is
necessary to know whether these contaminants pose a health risk, but it is often
incomplete for unregulated contaminants and is frequently being studied at the same
time UCMR monitoring is taking place. Some contaminants maybe harmful at low
levels; others maybe harmful only at much higher levels. UCMR is a tool to find out
what is in the drinking water, but additional information is needed to know whether
these contaminants pose a health risk.
How Can I Find Out the Results?
If a water system is participating and finds contaminants in the drinking water, they
will provide the information to their customers in an annual water quality report (called
a Consumer Confidence Report). This includes both regulated and unregulated
contaminants. Systems mail these reports directly to customers, and many reports are
available from EPA's Web site. EPA will also make the results available on-line via its
National Contaminant Occurrence Database. These results will be posted on an
ongoing basis after they have been reviewed for quality.
How Can I Learn More?
• General information on drinking water is available at EPA's drinking water
Web site (www.epa.gov/safewater) or by calling the Safe Drinking Water hotline
(800-426-4791).
• Additional information on UCMR is available at www.epa.gov/safewater/ucmr/
index.html.
Office of Water
www.epa.gov/safewater
EPA815-F-08-010
December 2008
------- |