United States
Environmental Protection
Agency
The Fourth Unregulated Contaminant Monitoring Rule (UCMR 4)
HAA Groups - Fact Sheet for Assessment Monitoring
Overview
EPA published the "Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 4) for Public Water Systems and
Announcement of Public Meeting" on December 20, 2016 (81 FR 92666). UCMR 4 includes Assessment Monitoring for a total
of 30 chemical contaminants including three brominated haloacetic acid (HAA) disinfection byproducts groups (shown in the
table at right) and two associated indicators (total organic carbon (TOC) and bromide). UCMR 4 also requires Assessment
Monitoring for:
•	Nine cyanotoxins and one cyanotoxin group.
•	17 additional contaminants: two metals; eight pesticides plus one pesticide manufacturing byproduct; three alcohols;
and three semivolatile organic chemicals.
Monitoring under UCMR 4 will occur from 2018-2020. For more information on these contaminants, please refer to the
respective UCMR 4 Fact Sheets.
Assessment Monitoring (HAA Groups)
¦	Applicable Water Systems: Community water systems (CWSs) and non-transient non-community water systems
(NTNCWSs) serving more than 10,000 retail customers (i.e., large systems), and a representative sample of 800 CWSs and
NTNCWSs serving 10,000 or fewer retail customers (i.e., small systems). UCMR 4 HAA monitoring only applies to public
water systems (PWSs) that are subject to Disinfectants and Disinfection Byproduct Rules (D/DBPRs) HAA5 monitoring
requirements.
¦	Timeframe and Frequency: For surface water (SW) and ground water under the direct influence of surface water (GWUDI)
systems, sampling will take place for four consecutive quarters over the course of 12 months; a total of four sampling events
that occur three months apart. For ground water (GW) systems, sampling will take place twice over the course of 12
months; a total of two sampling events that occur five to seven months apart.
¦	Monitoring Locations:
o HAA Groups: Taken at the D/DBPRs sampling locations described in 40 CFR 141.622. UCMR 4 HAA samples and
D/DBPRs HAA5 compliance monitoring samples may be collected by the PWS at the same time (see below
regarding laboratory and method requirements). See the Quick Reference Guides for Stage 1 and Stage 2 D/DBPRs
for more information about the HAA5 compliance monitoring requirements.
HAA Groups
Dichloroacetic acid (DCAA)
Monochloroacetic acid (MCAA)
Trichloroacetic acid (TCAA)
HAA5
Monobromoacetic acid (MBAA)
Dibromoacetic acid (DBAA)
Bromochloroacetic acid (BCAA)
Bromodichloroacetic acid (BDCAA)
Chlorodibromoacetic acid (CDBAA)
Tribromoacetic acid (TBAA)
HAA9
HAA6Br
Office of Water (MS-140)
EPA 815-F-16-006
December 2016

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o TOC and Bromide: Taken at source water influent locations representing untreated water entering the water
treatment plant (i.e., a location prior to any treatment). Must be collected at the same time as HAA samples.
¦	SW and GWUDI systems subject to the D/DBPRTOC monitoring must use their D/DBPRs TOC source water
sampling site(s) from 40 CFR 141.132.
¦	SW and GWUDI systems that are not subject to D/DBPRs TOC monitoring must use their Long Term 2
Enhanced Surface Water Treatment Rule (LT2) source water sampling site(s) (40 CFR 141.703).
¦	GW systems that are subject to the D/DBPRs collect TOC and bromide samples at the influents entering
their treatment train.
¦	Consecutive systems (PWSs that purchase 100 percent of their water) are not required to collect source
water samples for TOC or bromide analyses.
¦ Laboratories: UCMR 4 HAA samples must be analyzed by a UCMR 4 EPA UCMR approved laboratory using EPA Method
552.3 or 557 (both of which are compliance methods also approved for analysis of D/DBPRs samples). TOC and bromide
must be analyzed by methods already approved for compliance monitoring. For additional information on the D/DBPRs
compliance methods, see CFR 141.131(d). Minimum Reporting Levels (MRLs) for the individual HAAs are provided (40 CFR
141.40(a)(5)(v)) for quality control purposes. The HAA5 group is currently regulated in drinking water at a maximum
contaminant level (MCL) of 60 ng/L; all are disinfection by-products.
o Note: laboratories (including PWS laboratories) that wish to exclusively analyze TOC and/or bromide samples do
not need to undergo all of the steps for UCMR 4 laboratory approval. Rather, they must email
UCMR Sampling Coordinatorffiepa.gov by December 1, 2017 to register for the Lab Approval Program.
Next, the PWS laboratory must complete the registration and submit documentation that they are authorized by
their primacy state to analyze TOC and/or bromide compliance monitoring samples under the D/DBPRs by
December 15, 2017.
¦ Occurrence Data: The analytical results from UCMR 4 are stored in the National Contaminant Occurrence Database (NCOD).
For a summary of the NCOD results, tips for querying NCOD, and health effects information (including reference
concentrations, where available), please refer to the UCMR 4 Data Summary document.
Critical Deadlines and Requirements
Following Rule Publication
Due Date
Requirement
Report
through
SDWARS1
Contact
Sampling
Coordinator2
December 31, 2017
Large systems must update contact information, zip code(s),
sampling location(s), inventory information and monitoring
schedule. With the exception of monitoring schedule
changes, any subsequent changes must be submitted within
30 days of the change occurring. EPA will coordinate with the
small systems to collect the contact information, zip code(s)
and inventory information. After December 31, 2017, systems
must provide an explanation for any requested schedule
change and obtain EPA approval of the change.
X
X
(after
December
31, 2017)
February 21, 2017
Laboratories seeking approval must submit a registration
form to participate in the laboratory approval process.

X
April 19, 2017
Laboratories must complete and submit the necessary
laboratory approval application materials.

X
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Following Sample Collection
Due Date
Requirement
Report
through
SDWARS1
Contact
Sampling
Coordinator2
Within 120 days of
sample collection
Laboratories post data to SDWARS.
X

Within 60 days of
lab posting data
PWSs review and approve the data. If the PWS has not taken
action after 60 days, the data are considered approved and
ready for state and EPA review.
X

1.	Safe Drinking Water Accession and Review System.
2.	Contact via email at UCMR Sampling Coordinator(5)epa.gov.
Data Elements
EPA will collect the following data elements via SDWARS 4, an updated version of the data reporting system used in previous
UCMR actions.
Public Water System
Identification
(PWSID) Code
Sampling Point
Identification Code
Sample Collection Date
Analysis Batch
Identification Code
Laboratory
Identification Code
Public Water System
Name
Sampling Point Name
Sample Identification
Code
Analysis Date
Sample Event Code
Public Water System
Facility Identification
Code
Sampling Point Type
Code
Contaminant
Sample Analysis Type

Public Water System
Facility Name
Disinfectant Type
Analytical Method
Code
Analytical Results-Sign

Public Water System
Facility Type
Treatment Information
Extraction Batch
Identification Code
Analytical Result-
Measured Value

Water Source Type
Disinfectant Residual
Type
Extraction Date
Additional Value

Additional Information
The Public Notification Rule (40 CFR 141.207) requires PWSs to notify the persons served of the availability of the results
no later than 12-months after monitoring results are known. CWSs may include their public notice within their Consumer
Confidence Reports (CCRs).
Under the Consumer Confidence Report (CCR) Rule (40 CFR 141.153(d)) requires CWSs to report the monitoring results
whenever unregulated contaminants are detected. CCRs are to be sent to all billing customers each year by July 1. (The
CCR Rule does not apply to non-community water systems). To obtain a copy of your CCR, you should contact your water
supplier or you may find information for how to obtain a copy of the CCR in your water bill. Additional information about
the CCR including detains on reporting requirements can be found on the CCR Homepage.
For More Information
¦	Safe Drinking Water Hotline: 1-800-426-4791
¦	CDX/SDWARS Help Desk: 1-888-890-1995
¦	UCMR Homepage
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