oEPA
The Third Unregulated Contaminant Monitoring Rule (UCMR 3)
Data Summary: 2013-2015
Background
The EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) program to collect nationally
representative data for contaminants that may be present in drinking water but do not have regulatory
standards set under the Safe Drinking Water Act (SDWA). This monitoring is used by the agency to understand
the frequency and level of occurrence of unregulated contaminants in the nation's drinking water systems.
Every five years, taking into consideration the EPA's Contaminant Candidate List (CCL), the agency develops a
new list of UCMR contaminants for monitoring. SDWA calls for the EPA to:
• Issue a list of unregulated contaminants to be monitored by certain public water system (PWS) types1
every five years
• Require large PWSs (i.e., those that serve more than 10,000 people) to monitor their water for the
contaminants
• Require a nationally representative sample of small PWSs serving 10,000 or fewer people to monitor2
• Make analytical results available in a National Contaminant Occurrence Database (NCOD) for drinking
water
UCMR 3 required monitoring between 2013 and 2015 for the 30 contaminants (28 chemicals and two viruses)
listed in Table la and Table lb. UCMR 3 chemical contaminants were monitored under the UCMR Assessment
Monitoring (AM) or Screening Survey (SS) design; the viruses were monitored under the Pre-Screen Testing (PST)
design. For more information, refer to the EPA's UCMR 3 website. Contaminant health effects information that
was available at the time of UCMR 3 monitoring is provided in Table 2. The health information presented may no
longer be current or publicly available from the original reference. Summary details for contaminant occurrence
are shown in Table 3a and Table 3b and represent the final release of UCMR 3 analytical results. Before
conducting your own assessment of the data, please review the Data Considerations section.
1 UCMR 3 requirements applied to community water systems (CWSs) and non-transient non-community water systems (NTNCWSs). For
Pre-Screen Testing (PST) monitoring only, transient non-community water systems (TNCWSs) that were sourced by ground water and
served 1,000 or fewer people were also subject to being selected for participation. The use of "PWS" throughout this document refers to
participating CWSs, NTNCWSs, and TNCWSs. For more information on PWS types, visit the agency's website.
2 SDWA, as amended by Section 2021 of America's Water Infrastructure Act of 2018, calls for the EPA to require small PWSs serving
between 3,300 and 10,000 people to monitor for UCMR contaminants, subject to the availability of EPA appropriations and sufficient
laboratory capacity, and to require a nationally representative sample of small PWSs serving fewer than 3,300 people to monitor. This
expansion in small PWS monitoring applies to the fifth UCMR (UCMR 5) and subsequent monitoring cycles.
March 2024
Office of Water (MS-140)
EPA 815-S-24-004
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Table la. Chemical Contaminants and Methods
Contaminant
CASRN1
EPA
Method
Contaminant Classification
Monitoring
Requirement2
chromium (total)
7440-47-3
200.8
Metal
AM
cobalt
7440-48-4
200.8
Metal
AM
molybdenum
7439-98-7
200.8
Metal
AM
strontium
7440-24-6
200.8
Metal
AM
vanadium
7440-62-2
200.8
Metal
AM
chromium-6
18540-29-9
218.7
Metal
AM
chlorate
14866-68-3
300.1
Disinfection byproducts
AM
1,4-dioxane
123-91-1
522
Solvent
AM
1,1-dichloroethane
75-34-3
524.3
Solvent; chemical intermediate
AM
1,2,3-trichloropropane
96-18-4
524.3
Solvent; chemical intermediate
AM
1,3-butadiene
106-99-0
524.3
Industrial chemical
AM
bromochloromethane (Halon 1011)
74-97-5
524.3
Fire extinguishing fluid; chemical
intermediate
AM
chlorodifluoromethane (HCFC-22)
75-45-6
524.3
Refrigerant
AM
methyl bromide (bromomethane)
74-83-9
524.3
Pesticide
AM
methyl chloride (chloromethane)
74-87-3
524.3
Industrial chemical
AM
perfluorobutanesulfonic acid (PFBS)
375-73-5
537
Per- and polyfluoroalkyl
substances (PFAS)
AM
perfluoroheptanoic acid (PFHpA)
375-85-9
537
PFAS
AM
perfluorohexanesulfonic acid (PFHxS)
355-46-4
537
PFAS
AM
perfluorononanoic acid (PFNA)
375-95-1
537
PFAS
AM
perfluorooctanesulfonic acid (PFOS)
1763-23-1
537
PFAS
AM
perfluorooctanoic acid (PFOA)
335-67-1
537
PFAS
AM
16-a-hydroxyestradiol (estriol)
50-27-1
539
Hormone
SS
4-androstene-3,17-dione
63-05-8
539
Hormone
SS
equilin
474-86-2
539
Hormone
SS
estradiol (17|5-estradiol)
50-28-2
539
Hormone
SS
estrone
53-16-7
539
Hormone
SS
ethinyl estradiol (17a-ethynylestradiol)
57-63-6
539
Hormone
SS
testosterone
58-22-0
539
Hormone
SS
1 CASRN - Chemical Abstracts Service Registry Number
2 AM - Assessment Monitoring, SS - Screening Survey. For more information on UCMR 3 monitoring design, refer to the EPA's UCMR 3
website.
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Table lb. Microbiological Contaminants and Methods
Contaminant1
Method ID
Method Name
Monitoring
Requirement2
enteroviruses
EPA 1615A
Enterovirus cell culture
PST
enteroviruses
EPA 1615B
Enterovirus RT-qPCR
PST
noroviruses
EPA 1615C
Norovirus genogroup 1 with RT-qPCR primer set A
PST
noroviruses
EPA 1615D
Norovirus genogroup 1 with RT-qPCR primer set B
PST
noroviruses
EPA 1615E
Norovirus genogroup II
PST
total coliforms
SM 9223B
Colilert®
PST
E. coli
SM 9223B
Colilert®
PST
Enterococci
ASTM D6503-99
Enterolert®
PST
aerobic spores
SM 9218
Aerobic endospores
PST
male specific phage
EPA 1602
Coliphage in water by single agar layer procedure
PST
somatic phage
EPA 1602
Coliphage in water by single agar layer procedure
PST
1 Gray rows represent microbial indicators.
2 PST- Pre-Screen Testing. For more information on UCMR 3 monitoring design, refer to the EPA's UCMR 3 website.
Page 3 of 15
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Information About UCMR 3 Results
The purpose of this document is to (1) summarize UCMR 3 results and (2) provide context around UCMR 3
results in relation to EPA-established UCMR minimum reporting levels (MRLs) and, if available, reference
concentrations in drinking water.
The UCMR 3 MRLs are the lowest concentrations that laboratories were permitted to report to the EPA during
UCMR 3 monitoring. UCMR MRLs are determined using data from multiple laboratories that participate in the
EPA's MRL-setting studies and are not associated with contaminant health effects information. The EPA
establishes UCMR MRLs to ensure consistency in the quality of the information reported to the agency.
Depending on the available health and toxicological information for a UCMR 3 contaminant, a reference
concentration in drinking water may have been available. The reference concentrations identified in this
document do not represent regulatory limits or action levels and should not be interpreted as an indication of
future agency actions.
Community water systems (CWSs) required to monitor under UCMR must inform their customers of UCMR
results (including the average and range of results) in their annual Consumer Confidence Report (CCR). See 40
CFR 141.153(d)(7) for the CCR regulatory requirements and Section IV of the EPA's guidance Preparing Your
Drinking Water Consumer Confidence Report for details on the content of the report. Additional resources are
available on the EPA's CCR Compliance Help webpage.
Non-transient non-community water systems (NTNCWSs) (e.g., a school that operates its own drinking water
system) and CWSs required to monitor under UCMR must inform their customers of the availability of UCMR
results through Tier 3 Public Notification (PN). See 40 CFR 141.207 for the PN regulatory requirements and the
EPA's PN Compliance Help webpage for guidance.
UCMR occurrence data are used to inform the agency's Regulatory Determination process (i.e., the process that
addresses potential regulatory actions for unregulated contaminants). State and local officials may also use the
UCMR data to assess the need for actions to protect public health. States may establish requirements or levels
(regulatory or non-regulatory) for drinking water contaminants not yet regulated by the EPA. PWSs are
responsible for being aware of and complying with their state's requirements, if any.
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Reference Concentrations
Table 2 provides reference concentrations for chemical contaminants monitored under UCMR 3, if available at
the time of monitoring (2013-2015). Information cited was current as of January 2017 with the publication of
the final dataset. Thus, the health information may no longer be current or publicly available from the original
reference. Many of the references are hyperlinked to where the most recent information can be found.
To identify reference concentrations, the EPA applied the following principles:
(1) Reference concentrations were based on the following publicly available resources:
a. 2012 Drinking Water Standards and Health Advisories.
b. CCL 4 Contaminant Information Sheets.
c. 2013 Human Health Benchmarks for Pesticides (HHBPs),
d. Integrated Risk Information System (IRIS) Assessments, and
e. 2014 Preliminary Regulatory Determinations for Contaminants on CCL 3
The above resources are the products (or compilation) of peer-reviewed health assessments. The
reference concentrations are subject to change as new health assessments are completed; they are not
legally enforceable federal standards.
(2) If health information was available from more than one of the resources listed above, the most recent
health information was used.
(3) If both cancer and non-cancer reference concentrations were available from the most recent resource,
the lower (more conservative) of the two concentrations was used.
(4) If non-cancer health effects were the basis for the reference concentration, and both chronic and short-
term exposure values were available from the most recent resource, the lower concentration
(associated with the chronic exposure) was used.
(5) For chemicals with reference concentrations based on a cancer endpoint, the table presents a range of
concentrations associated with risks of 10 s (1 in 1,000,000) to 10"4 (1 in 10,000) over a lifetime.
(6) For chemicals with reference concentrations based on a non-cancer endpoint, the exposure duration
(short-term, intermediate/long-term, chronic) associated with the toxic effect is shown.
Please review the references and footnotes in Table 2 for additional health effects information. Recognizing that
additional health effects information will become available over time, those attempting to assess UCMR
occurrence data are encouraged to visit the EPA's Non-Regulatory Health-Based Drinking Water Levels webpage
for the most recent information.
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Table 2. UCMR Minimum Reporting Levels (MRLs) and Reference Concentrations at the Time of Monitoring
(2013-2015)
Chemical Contaminant
UCMR
MRL
(Hg/L)
Reference
Concentration
(Hg/L)1
Reference Concentration based
on a Cancer Endpoint (Y/N)1
EPA References1
chromium (total)
0.2
100
N (chronic exposure)
The MCL for the National Primary Drinking Water Regulation
cobalt
1
70
N (intermediate exposure)
Contaminant Information Sheets for the Final CCL 4
molybdenum2
1
40
N (chronic exposure)
2012 Edition of the Health Advisories Table
strontium3
0.3
1,500
N (chronic exposure)
Federal Register Notice for the Preliminary Regulatory
Determinations for Contaminants on CCL 3
vanadium4
0.2
21
N (intermediate exposure)
Contaminant Information Sheets for the Final CCL 4
chromium-65
0.03
-
-
-
chlorate
20
210
N (chronic exposure)
Contaminant Information Sheets for the Final CCL 4
1,4-dioxane6
0.07
0.35 to 35
Y
2012 Edition of the Health Advisories Table
1,1-dichloroethane6
0.03
6.14 to 614
Y
Contaminant Information Sheets for the Final CCL 4
1,2,3-trichloropropane6'7'8
0.03
0.0004 to 0.04
Y
2009 Integrated Risk Information System (IRIS) Assessment
1,3-butadiene6'7
0.1
0.0103 to 1.03
Y
Contaminant Information Sheets for the Final CCL 4
Halon 10119
0.06
90
N (chronic exposure)
2012 Edition of the Health Advisories Table
HCFC-2210
0.08
-
-
-
bromomethane
0.2
140
N (chronic exposure)
2013 Human Health Benchmarks for Pesticides (HHBPs)
chloromethane6
0.2
2.69 to 269
Y
Contaminant Information Sheets for the Final CCL 4
1 The health information reflects what was available during UCMR 3 monitoring (2013-2015). Information cited was current as of January 2017 with the publication of the final
dataset. Thus, the health information may no longer be current or publicly available from the original reference. Many of the references are hyperlinked to where the most
recent information can be found.
2 The 2012 Edition of the Health Advisories Table (40 |ag/l) and the CCL 4 Contaminant Information Sheets (35 pg/L) have slightly different reference values for molybdenum due
to rounding.
3 The reference concentration is based on the HRL cited in the preliminary regulatory determination for strontium [Docket No. EPA-HQ-OW-2012-0155].
4 The assessment for the 1992 Agency for Toxic Substances and Disease Registry (ATSDR) Minimal Risk Level used for vanadium in the CCL 4 Contaminant Information Sheets is
no longer publicly available and has been replaced by a new assessment (ATSDR. 2012). The ATSDR Minimal Risk Level (reference dose equivalent) was 0.003 mg/kg/day for
minor renal effects in an animal study (ATSDR, 1992) compared to 0.01 mg/kg/day for lack of minor effects in blood pressure, body weight, and hematological parameters in a
human study with a 12-week exposure (ATSDR, 2012).
5 In process/draft EPA Integrated Risk Information System (IRIS) assessment for chromium-6.
6 Reference Concentration range based on cancer risk of 10 6 to 10 4.
710 6 cancer risk < MRL < 10-4 cancer risk. The MRL was established based on the capability of the analytical method at the time of monitoring (2013-2015).
8 To derive the reference concentration, age dependent adjustment factors were applied to the IRIS oral slope factor of 30 per mg/kg-day (calculated using adult exposure data)
to address presumed early-life susceptibility for 1,2,3-trichloropropane (see the EPA's Guidelines for Carcinogen Risk Assessment).
9 The 2012 Edition of the Health Advisories Table (90 pg/L) and the CCL 4 Contaminant Information Sheets (70 pg/L) have slightly different reference values for Halon 1011 due
to rounding.
10 The CCL 4 Contaminant Information Sheets provide a reference level of 31.5 pg/L for HCFC-22; the number is based on a single LOAEL (lowest-observed-adverse-effect level)
from a 1983 study.
Page 6 of 15
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Chemical Contaminant
UCMR
MRL
(Hg/L)
Reference
Concentration
(Hg/L)1
Reference Concentration based
on a Cancer Endpoint (Y/N)1
EPA References1
PFBS
0.09
-
-
-
PFHpA
0.01
-
-
-
PFHxS
0.03
-
-
-
PFNA
0.02
-
-
-
PFOS
0.04
0.07
N (chronic exposure)
2009 Provisional Health Advisorv and SuoDortins
Documentation for PFOS
PFOA
0.02
0.07
N (chronic exposure)
2009 Provisional Health Advisorv and Suooortins
Documentation for PFOA
estriol
0.0008
0.35
N (chronic exposure)
Contaminant Information Sheets for the Final CCL4
4-androstene-3,17-dione
0.0003
-
-
-
equilin
0.004
0.35
N (chronic exposure)
Contaminant Information Sheets for the Final CCL4
17(3-estradiol6
0.0004
0.0009 to 0.09
Y
Contaminant Information Sheets for the Final CCL4
estrone
0.002
0.35
N (chronic exposure)
Contaminant Information Sheets for the Final CCL4
17a-ethynylestradiol
0.0009
0.035
N (chronic exposure)
Contaminant Information Sheets for the Final CCL4
testosterone
0.0001
-
-
-
Page 7 of 15
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Terms and Definitions
a) UCMR MRL- EPA-established UCMR Minimum Reporting Level. The lowest concentration that laboratories may report
to the EPA during UCMR 3 monitoring. MRLs are not associated with health effects information. More specifically, an
MRL is the quantitation limit for a contaminant that is considered achievable, with 95% confidence, by at least 75% of
laboratories nationwide using a specified analytical method (recognizing that individual laboratories may be able to
measure at lower levels). [Note: The Agency for Toxic Substances and Disease Registry (ATSDR) uses the term "MRL"
for a different purpose [i.e., to describe "Minimal Risk Level"). The UCMR term and the ATSDR term have no
relationship to each other.]
b) Ref Cone - Reference Concentration. Based on publicly available health information found in the following EPA
resources: 2012 Edition of the Drinking Water Standards and Health Advisories Tables [i.e., Health Advisories (HA)], the
CCL 4 Contaminant Information Sheets [i.e., Health Reference Levels (HRLs)], and the 2013 Human Health Benchmarks
for Pesticides (i.e., HHBPs). These reference concentrations are derived from peer-reviewed health assessments
published by the EPA or other governmental agencies. They are not legally enforceable federal standards and are subject
to change as new health assessments are completed. Depending on available health effects information, a reference
concentration in drinking water can be derived from a reference dose (i.e., a non-cancer endpoint) or a cancer slope
factor (CSF) (i.e., a cancer endpoint), and considers additional assumptions about body weight and drinking water intake.
c) HA - Health Advisory. Provides information on a contaminant that can cause negative human health effects and is known
or anticipated to occur in drinking water. SDWA authorizes the EPA to issue HAs for contaminants that are not subject to
a National Primary Drinking Water Regulation (NPDWR). The EPA's HAs are non-enforceable and non-regulatory and
provide technical information to state agencies and other public health officials on health effects, analytical methods,
and treatment technologies associated with drinking water contaminants. The HA documents include the derivation of
the HA levels, which are the concentrations of contaminants at or below which adverse health effects are not anticipated
to occur over specific exposure durations, such as one day, 10 days, or a lifetime. The lifetime HA for the drinking water
contaminant is calculated from its associated Drinking Water Equivalent Level (DWEL), obtained from its reference dose,
and incorporates a drinking water Relative Source Contribution (RSC) factor of contaminant-specific data or a default of
20% of total exposure from all sources.
d) HRL- Health Reference Level. Derived during the Contaminant Candidate List (CCL) process for screening purposes. HRLs
are used in the EPA's Regulatory Determination process as risk-derived concentrations against which to evaluate
occurrence data to determine if contaminants occur at levels of public health concern. HRLs are not final determinations
about the level of a contaminant in drinking water that is necessary to protect any particular population and, in some
cases, are derived prior to development of a complete exposure assessment using the best available data. HRLs are not
legally enforceable federal standards. To determine the HRL for a chemical, the agency considers adverse health effects
that may pose a greater risk to specific lifestages and other sensitive groups which represent a meaningful portion of the
population.
e) HHBP - Human Health Benchmarks for Pesticides. The EPA has developed HHBPs for informational purposes for use by
states, PWSs, and the public to assist with risk management decisions and to prioritize monitoring efforts for pesticides
that have no drinking water standards or Health Advisories. The HHBPs are not legally enforceable federal standards.
f) MCL- Maximum Contaminant Level. The highest level of a contaminant that is allowed in drinking water. MCLs are set as
close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are
enforceable standards.
g) Cancer Risk of 10 ® to 10"4 (chronic exposure) - The concentration of a contaminant in drinking water corresponding to
an excess estimated lifetime cancer risk of one-in-a-million (1 x 10"6) to one-in-ten thousand (1 x 10"4). The 2012 Edition
of the Health Advisories provide the cancer risk at 1 x 10"4. The CCL 4 Contaminant Information Sheets provide the cancer
risk at 1 x 10"6. Cancer risk is derived using drinking water exposure assumptions, risk level, and a cancer slope factor
(CSF), a toxicity value for evaluating the probability of an individual developing cancer from exposure to a certain level of
a contaminant over a lifetime. Generally, when evaluating risk for health endpoints associated with chronic exposures,
averages from multiple measurements (potentially spanning a period of time) are more representative of a lifetime risk
than results from a single measurement.
Page 8 of 15
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h) Non-cancer (short-term exposure) - Based on a reference dose, which is a non-cancer estimate (with uncertainty
spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of deleterious effects after short-term exposure. Short-term
exposure typically refers to animal toxicological studies with an exposure duration of days to weeks. One-day is
protective for up to 1 day of exposure and is typically based on an animal study with a duration of 7 days or less. Ten-day
is protective for up to 10 days of exposure and is typically based on an animal study with a duration of 7 to 30 days.
Generally, when evaluating risk for health endpoints associated with short-term exposures, a single detection is more
relevant.
i) Non-cancer (intermediate/longer-term exposure) - Based on a reference dose, which is a non-cancer estimate (with
uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including
sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects after intermediate/longer-term
exposure. Intermediate/longer-term exposure typically refers to animal toxicological studies with an exposure duration
of weeks to months.
j) Non-cancer (chronic exposure) - Based on a reference dose, which is a non-cancer estimate (with uncertainty spanning
perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is
likely to be without an appreciable risk of deleterious effects after long-term exposure. Chronic exposure typically refers
to animal toxicological studies with an exposure duration of months to years, representing a lifetime exposure in
humans. Generally, when evaluating risk for health endpoints associated with chronic exposures, averages from multiple
measurements (potentially spanning a period of time) are more representative of a lifetime risk than results from a
single measurement.
Page 9 of 15
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Table 3a. UCMR 3 Data Summary for Chemical Contaminants1
UCMR
Ref Cone3
(Hg/L)
Total
Number
Number
% of total
Total number
Number of
Number of
PWSs with
results >Ref
Cone
% of PWSs
Contaminant
MRL2
number
of results
of results
results >Ref
of PWSs with
PWSs with
with results
(Hg/L)
of results4
>MRL
>Ref Cone
Cone
results4
results >MRL
>Ref Cone
chromium (total)
0.2
100
62,917
31,773
1
0.002%
4,922
3,660
1
0.02%
cobalt
1
70
62,982
833
3
0.005%
4,922
247
3
0.06%
molybdenum
1
40
62,986
25,377
151
0.2%
4,922
2,546
40
0.8%
strontium
0.3
1,500
62,913
62,799
1,739
2.8%
4,922
4,922
286
5.8%
vanadium
0.2
21
62,981
37,954
1,680
2.7%
4,922
3,625
163
3.3%
chromium-6
0.03
-
62,837
47,503
-
-
4,919
4,401
-
-
chlorate
20
210
62,859
34,426
9,796
15.6%
4,918
3,391
1,896
38.6%
1,4-dioxane
0.07
0.35/355
36,810
4,197
1,081/06
2.9% / 0%6
4,915
1,077
341/ 06
6.9% / 0%6
1,1-dichloroethane
0.03
6.14/6145
36,848
835
I/O6
0.003% / 0%6
4,916
244
I/O6
0.02% / 0%6
1,2,3-trichloropropane
0.03
0.0004 / 0.045
36,848
256
256/1976
0.7% / 0.5%6
4,916
67
67/556
1.4% / 1.1%6
1,3-butadiene
0.1
0.0103 / 1.035
36,848
2
2 / 06
0.005% / 0%6
4,916
2
2 / 06
0.04% / 0%6
Halon 1011
0.06
90
36,847
655
0
0%
4,916
309
0
0%
HCFC-22
0.08
-
36,847
827
-
-
4,916
286
-
-
bromomethane
0.2
140
36,848
115
0
0%
4,916
49
0
0%
chloromethane
0.2
2.69/2695
36,845
283
20 /06
0.05% / 0%6
4,916
138
8 / 06
0.2% / 0%6
PFBS
0.09
-
36,972
19
-
-
4,920
8
-
-
PFHpA
0.01
-
36,972
236
-
-
4,920
86
-
-
PFHxS
0.03
-
36,971
207
-
-
4,920
55
-
-
PFNA
0.02
-
36,972
19
-
-
4,920
14
-
-
PFOS
0.04
0.07
36,972
292
124
0.3%
4,920
95
46
0.9%
PFOA
0.02
0.07
36,972
379
32
0.09%
4,920
117
13
0.3%
estriol
0.0008
0.35
11,796
4
0
0%
1,201
4
0
0%
4-androstene-3,17-dione
0.0003
-
11,796
101
-
-
1,201
77
-
-
equilin
0.004
0.35
11,796
0
0
0%
1,201
0
0
0%
17(3-estradiol
0.0004
0.0009 / 0.095
11,795
4
I/O6
0.008% / 0%6
1,201
2
I/O6
0.08% / 0%6
estrone
0.002
0.35
11,796
0
0
0%
1,201
0
0
0%
17a-ethynylestradiol
0.0009
0.035
11,796
4
0
0%
1,201
4
0
0%
testosterone
0.0001
-
11,795
72
-
-
1,201
65
-
-
1 Analytical results from the UCMR program are reported by laboratories and provided by the agency in micrograms/liter (|ig/L, or parts per billion). To convert results in |Jg/Lto
nanograms/liter (ng/L, or parts per trillion), multiply the value by 1,000. UCMR results are presented as single measurements and do not represent a locational running annual average.
2 UCMR MRL- EPA-established UCMR Minimum Reporting Level. Based on laboratory capability; not related to contaminant health effects information.
3 Ref Cone - Reference Concentration. SeeTerms and Definitions.
4 UCMR 3 chemical contaminants were monitored under either the UCMR Assessment Monitoring (AM) or Screening Survey (SS) design, affecting the number of results and PWSs with
results for each contaminant. For more information, refer to the EPA's UCMR 3 website. For the metals, samples were collected at the entry point to the distribution system (EP) and the
distribution system at maximum residence time (MR), increasing their total AM results.
5 The first number is the reference concentration for 10~6 cancer risk; the second number is the reference concentration for 10~4 cancer risk.
6 The first number is associated with the first reference concentration; the second number is associated with the second reference concentration.
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Table 3b. UCMR 3 Data Summary for Microbiological Contaminants
Contaminant1
UCMR MRL2
Units
Total number
of results3
Number of
results >MRL
Total number of
PWSs with results3
Number of PWSs with
results >MRL
enteroviruses (cell culture)
0.002
MPN4/L5
1,044
2
789
2
enteroviruses (RT-qPCR6)
0.398
GC7/L
1,044
6
789
6
noroviruses GIA8
0.398
GC/L
1,044
4
789
4
noroviruses GIB9
0.398
GC/L
1,044
2
789
2
noroviruses Gil10
0.398
GC/L
1,044
4
789
4
total coliforms
1
MPN/lOOmL
1,045
57
791
53
E. coli
1
MPN/lOOmL
1,045
3
791
3
Enterococci
1
MPN/lOOmL
1,044
41
792
41
aerobic spores
1
SFC^VlOOmL12
1,047
317
793
252
male specific phage
1
PFU13/100mL
1,029
14
783
14
somatic phage
1
PFU/lOOmL
1,029
5
783
5
1 Gray rows represent results for microbial indicators.
2 UCMR MRL - EPA-established UCMR Minimum Reporting Level. Based on laboratory capability of the analytical method; not related to contaminant health effects information.
Under UCMR 3, microbe analytical results were reported as "below", "at", or "above" MRL. It is important to note that microbial contamination can be transient in nature and
microbial results under UCMR 3 should be interpreted in the context of the time samples were collected. However, the presence of any UCMR 3 microbe indicates a potential
vulnerability of the PWS to contamination.
3 UCMR 3 microbiological contaminants were monitored under the Pre-Screen Testing (PST) design. For more information, refer to the EPA's UCMR 3 website.
4 MPN - Most Probable Number
5 L - liters
6 RT-qPCR - Reverse Transcription-Polymerase Chain Reaction
7 GC- Genomic Copies
8 Noroviruses GIA - qPCR analysis of norovirus genogroup I with RT-qPCR primer set A
9 Noroviruses GIB - qPCR analysis of norovirus genogroup I with RT-qPCR primer set B
10 Noroviruses Gil - qPCR analysis of norovirus genogroup II
11 SFO - Spore Forming Units
12 mL- milliliters
13 PFU - Plaque Forming Units
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Data Considerations
The UCMR 3 analytical results are publicly available through the UCMR Archival Data Finder and as text files.
The UCMR Archival Data Finder allows people to easily search for, summarize, and download the UCMR 3 analytical results.
Results can be filtered using multiple data fields, including public water system (PWS), PWS size, state, EPA Region,
contaminant, source water type, and results at or above UCMR minimum reporting levels (MRLs) (data definitions provided
in Table 4). Selected results can be viewed online or downloaded as a Microsoft Excel file (.xlsx). Additional resources for
the UCMR Archival Data Finder are available here. Note: Results for the microbial indicators (gray rows in Table 3b) are not
included in the UCMR Archival Data Finder (see UCMR3_Virus_lndicators.txt as described below).
For those interested in large-scale data processing using statistical or data analysis software, the EPA recommends using the
occurrence data text files containing the UCMR 3 analytical results as well as additional information reported during
monitoring. Data are provided in tab delimited text files (.txt) (see below for descriptions), with field names included in the
first row of each file and no text qualifier. The EPA recommends importing all ID fields into your choice of software (e.g.,
Microsoft Excel, Microsoft Access) as text since some of the IDs can otherwise be misinterpreted as long integer field types
when they contain alpha characters.
• To download the occurrence data text files (data definitions provided in Table 5). select one of the following zip
(.zip) files from UCMR 3 (2013-2015) Occurrence Data:
o UCMR 3 Occurrence Data Text Files to view all the analytical results (i.e., results for all contaminants
reported by all PWSs). Since the UCMR3_All.txt file is too large to be imported into Excel, you can try
other applications (e.g., Microsoft Access) or import a subset of the data as described below.
o UCMR 3 Occurrence Data Text Files by State to view all the analytical results, organized by Tribes and
states. Within that zip file, one text file (UCMR3_AII_Tribes_AK_LA.txt) will have all results for Tribal
PWSs and for the states starting alphabetically with A through L; another file (UCMR3_AII_MA_WY.txt)
will have all results for the states starting alphabetically with M through W. The results are organized this
way to address file size limitations and streamline data management.
o UCMR 3 Occurrence Data Text Files by Method Classification to view all the analytical results, organized
by analytical method. Within that zip file, you will find individual text files with results organized by
method (e.g., a Method 300.1 file with results for chlorate).
• The following text files for additional data elements and indicators (i.e., information beyond analytical results for
the 30 UCMR 3 contaminants) are also contained in each of the above zip files:
o UCMR3_ZIPCodes.txt - U.S. Postal Service ZIP Code(s) for all areas served by a PWS (data definitions
provided in Table 6)
o UCMR3_Virus_lndicators.txt - Analytical results from PST monitoring for microbiological indicators
including total coliforms, E. coli, Enterococci, aerobic spores, male specific phage, and somatic phage (data
definitions provided in Table 5)
o UCMR3_Disinfectant_AddtlDataElem.txt - Disinfectant Type (data definitions provided in Table 7)
For step-by-step details on using the UCMR Archival Data Finder and occurrence data text files, please refer to the
document Instructions for Accessing UCMR Results. Additional reference material is available on the EPA's UCMR 3 website.
In addition to reporting occurrence data for UCMR 3 contaminants, the EPA tasked the laboratories it contracted to analyze
small PWS samples with reporting results for sec-butylbenzene, n-propylbenzene, tellurium, germanium, and manganese.
These additional unregulated contaminants were within the scope of the methods already performed for the UCMR 3
contaminants. The results from small PWS monitoring for the additional contaminants are included in the UCMR Archival
Data Finder and the occurrence data text files.
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Table 4. UCMR 3 Data Definitions for the UCMR Archival Data Finder
The data definitions below are specific to the UCMR 3 data. The UCMR Archival Data Finder also contains data from
additional UCMR cycles, which may have different definitions for the provided fields. Please refer to the document
Instructions for Accessing UCMR Results for data definitions specific to each cycle.
Field Name
Definition
UCMR Cycle
UCMR cycle and monitoring years. Results may have sample collection dates outside the designated
UCMR sample collection timeframe (e.g., resample collection): UCMR 3 (2013-2015)
PWS ID
Public Water System (PWS) Identification Code. The code used to identify each PWS. The code begins
with the standard 2-character postal state abbreviation or Region code for Tribes; the remaining 7
numbers are unique to each PWS in the state. Utah PWS IDs begin with 4 letters (UTAH) followed by
5 numbers
PWS Name
Name of the PWS
Contaminant
The UCMR 3 contaminant analyzed
Result
Numeric value of the analytical result in |ag/L for the chemical contaminants and GC/L or MPN/L for
the viruses. Results less than the UCMR MRL are indicated by 10,000)
Facility Water Type
Source of water at the facility: SW (surface water), GW (ground water), GU (ground water under the
direct influence of surface water), MX (any combination of SW, GW, and GU)
Sample Point Type
Sampling Point Type Code: EP (entry point to the distribution system), MR (distribution system at
maximum residence time)
EPA Region
EPA Region (states): Region 1 (CT, ME, MA, NH, Rl, VT), Region 2 (NJ, NY, PR [Puerto Rico], VI [Virgin
Islands]), Region 3 (DE, DC, MD, PA, VA, WV), Region 4 (AL, FL, GA, KY, MS, NC, SC, TN), Region 5 (IL,
IN, Ml, MN, OH, Wl), Region 6 (AR, LA, NM, OK, TX), Region 7 (IA, KS, MO, NE), Region 8 (CO, MT, ND,
SD, UT, WY), Region 9 (AZ, CA, HI, NV, AS [American Samoa], GU [Guam], MP [Northern Marianas
Islands], NN [Navajo Nation]), Region 10 (AK, ID, OR, WA)
State
State abbreviation. Tribal PWSs without primacy are attributed to an EPA Region (01, 05, 06, 08, 09,
10)
Associated Facility ID
Identification code for the facility of the associated MR
Associated Sample Point ID
Identification code for the sample point of the associated MR
Monitoring Requirement
AM (Assessment Monitoring), SS (Screening Survey), PST (Pre-Screen Testing)
Minimum Reporting Level
(MRL)
Minimum Reporting Level defined by UCMR 3 in |ag/L for the chemical contaminants and GC/L or
MPN/L for the viruses. Based on laboratory capability; not related to contaminant health effects
information (see Terms and Definitions)
UCMR1 Sample Type
Null for UCMR 3
CASRN
Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical
Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic
and inorganic compounds, polymers elements, nuclear particles, etc.) in the open scientific
literature. It contains up to 10 digits, separated by hyphens into three parts
DTXSID
Distributed Structure-Searchable Toxicity Substance Identifier (DTXSID) is a unique substance
identifier used in the EPA's CompTox Chemicals database, where a substance can be any single
chemical, mixture, or polymer
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Table 5. Data Definitions for Text Files: UCMR3_AII, UCMR3_AII_Tribes_AK_LA,
UCMR3_AII_MA_WY, \JCMR3_MethodNumber, and UCMR3_Virus_lndicators
Field Name
Definition
PWSID
Public Water System (PWS) Identification Code. The code used to identify each PWS. The code begins
with the standard 2-character postal state abbreviation or Region code for Tribes; the remaining 7
numbers are unique to each PWS in the state. Utah PWS IDs begin with 4 letters (UTAH) followed by 5
numbers
PWSName
Name of the PWS
Size
Size category of the PWS for UCMR 3, based on retail population as indicated by the Safe Drinking
Water Information System (Federal) (SDWIS/FED) as of December 31, 2010: S (< 10,000), L (> 10,000)
FacilitylD
Identification code (5-digit number) for each applicable facility associated with water treatment or
delivery at the PWS
FacilityName
Name of the facility at the PWS
FacilityWaterType
Source of water at the facility: SW (surface water), GW (ground water), GU (ground water under the
direct influence of surface water), MX (any combination of SW, GW, and GU)
SamplePointID
Identification code for each sample point location at the PWS
SamplePointName
Name of the sample point at the PWS
SamplePointType
Sampling Point Type Code: EP (entry point to the distribution system), MR (distribution system at
maximum residence time)
AssociatedFacilitylD
Identification code for the facility of the associated MR
AssociatedSamplePointID
Identification code for the sample point of the associated MR
CollectionDate
Date of sample collection (month, day, year)
SamplelD
Identification code for each sample
Contaminant
The UCMR 3 contaminant analyzed
MRL
Minimum Reporting Level (MRL) defined by UCMR 3 in |ag/L for the chemical contaminants and GC/L or
MPN/L for the viruses; for UCMR3_Virus_lndicators.txt only, in SFO/lOOmL, PFU/lOOmL, or MPN/lOOmL
for the indicators. Based on laboratory capability; not related to contaminant health effects information
(see Terms and Definitions)
Units
Units of the UCMR MRL and analytical results: ng/L (micrograms per liter), GC/L (genomic copies per
liter), MPN/L (most probable number per liter); for UCMR3_Virus_lndicators.txt only, SFO/lOOmL
(spore forming units per one hundred milliliters), PFU/lOOmL (plaque forming units per one hundred
milliliters), MPN/lOOmL (most probable number per one hundred milliliters)
MethodID
Identification code of the analytical method
AnalyticalResultsSign
Sign indicating whether the analytical result is less than (<) the UCMR MRL or equal to (=) a numeric
value at or above the UCMR MRL
AnalyticalResultValue
Numeric value of the analytical result in pg/L for the chemical contaminants and GC/L or MPN/L for the
viruses; for UCMR3_Virus_lndicators.txt only, in SFO/lOOmL, PFU/lOOmL, or MPN/lOOmL for the
indicators. Null (or blank) values represent results less than the UCMR MRL
SampleEventCode
Identification code for each sample event: SE1, SE2, SE3, SE4
MonitoringRequirement
AM (Assessment Monitoring), SS (Screening Survey), PST (Pre-Screen Testing)
Region
EPA Region (states): 1 (CT, ME, MA, NH, Rl, VT), 2 (NJ, NY, PR [Puerto Rico], VI [Virgin Islands]), 3 (DE,
DC, MD, PA, VA, WV), 4 (AL, FL, GA, KY, MS, NC, SC, TN), 5 (IL, IN, Ml, MN, OH, Wl), 6 (AR, LA, NM, OK,
TX), 7 (IA, KS, MO, NE), 8 (CO, MT, ND, SD, UT, WY), 9 (AZ, CA, HI, NV, AS [American Samoa], GU [Guam],
MP [Northern Marianas Islands], NN [Navajo Nation]), 10 (AK, ID, OR, WA)
State
State abbreviation. Tribal PWSs without primacy are attributed to an EPA Region (01, 05, 06, 08, 09,10)
UCMRlSampleType
Null for UCMR 3
Table 6. Data Definitions for Text File: UCMR3_ZIPCodes
Field Name
Definition
ZIPCODE
U.S. Postal Service ZIP Code(s) for all areas served by a PWS. This is entered by the PWS
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Table 7. Data Definitions for Text File: UCMR3 Disinfectant AddtlDataElem
Additional Data Element
Definition and Response Options
DisinfectantType
All of the disinfectants/oxidants that have been added prior to the entry point to the distribution
system. Please select ALL that apply.
CLGA = gaseous chlorine, CLOF = offsite generated hypochlorite (stored as a liquid form), CLON = onsite
generated hypochlorite, CAGC = chloramine (formed with gaseous chlorine), CAOF = chloramine
(formed with offsite hypochlorite), CAON = chloramine (formed with onsite hypochlorite), CLDO =
chlorine dioxide, OZON = ozone, ULVL = ultraviolet light, OTHD = other types of disinfectant, NODU =
no disinfectant used
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