Announcement of Final Rule: Unregulated 

Contaminant Monitoring Rule (UCMR 3) for 

Public Water Systems 

Summary 

Under the third Unregulated Contaminant Monitoring Rule (UCMR 3), large public water 

systems (PWSs) and a representative sample of small PWSs will monitor for 28 chemical 

contaminants and two viruses from January 2013 through December 2015. UCMR 3 will provide 

EPA and other interested parties with scientifically valid data on the occurrence of these 

contaminants in drinking water, permitting the assessment of the number of people potentially 

being exposed and the levels of that exposure. The data represent one of the primary sources of 

occurrence and exposure information the Agency uses to develop regulatory decisions for these 

emerging contaminants. 

Background 

Section 1445(a)(2) of the 1996 Safe Drinking Water Act (SDWA) amendments requires 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 

Regulation (UCMR 1) was published on September 17, 1999, and the second (UCMR 2) was 

published on January 4, 2007. This monitoring provides a basis for future regulatory actions to 

protect public health. The UCMR 3 proposed rule was published in the Federal Register on 

March 3, 2011. 

About this regulation 

UCMR monitoring helps the Agency understand contaminant occurrence in drinking water and 

supports determinations as to whether particular contaminants need to be regulated. This final 

rule requires PWSs to monitor for the 28 chemical contaminants and two viruses shown in 

Exhibit 1. 

UCMR 3 samples will be collected at entry points to the distribution system (EPTDSs). 

Additionally, monitoring for total chromium, chromium-6, cobalt, molybdenum, strontium, 

vanadium, and chlorate will also take place at the distribution system maximum residence time 

(DSMRT) location. PWSs may perform sampling at representative ground water sampling 

locations and representative intakes from wholesalers. 

Sampling frequency will depend on the PWS water type. PWSs with surface water or “ground water 

under the direct influence of surface water” will monitor four times (quarterly) during their 

applicable year of monitoring. PWSs with ground water will monitor twice (five to seven months 

apart) during their applicable year of monitoring. PWSs can adjust the monitoring schedule initially 

established by EPA. 

EPA 815-R-12-001 Page 1 of 5 April 2012 
 

Exhibit 1: UCMR 3 Final Contaminant Lists 

List 1, Assessment Monitoring 

1,4-dioxane vanadium 

molybdenum strontium 

cobalt chromium-6 (hexavalent chromium)1 

1,2,3-trichloropropane total chromium2 

chlorate perfluorooctanesulfonic acid (PFOS) 

1,3-butadiene perfluorooctanoic acid (PFOA) 

chloromethane (methyl chloride) perfluorononanoic acid (PFNA) 

1,1-dichloroethane perfluorohexanesulfonic acid (PFHxS) 

bromochloromethane (Halon 1011) perfluoroheptanoic acid (PFHpA) 

bromomethane (methyl bromide) perfluorobutanesulfonic acid (PFBS) 

chlorodifluoromethane (HCFC-22) 

List 2, Screening Survey 

17-β-estradiol estriol 

17-α-ethynylestradiol (ethinyl estradiol) equilin 

estrone testosterone 

4-androstene-3,17-dione 

List 3, Pre-Screen Testing3 

enteroviruses noroviruses 

1. Chromium-6 will be measured as soluble chromate (ion). 

2. 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. 

3. EPA will collect the samples from List 3 sampling locations, and will pay for all sampling and analysis costs associated 

with virus and indicator monitoring at these small systems. 

EPA 815-R-12-001 Page 2 of 5 April 2012 
EPA generally divides unregulated contaminant monitoring into three types of monitoring, or 

“lists”. UCMR 3 includes monitoring under each of the three lists, as follows: 

	 Assessment Monitoring (List 1): 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) will monitor for 21 chemicals contaminants. 

	 Screening Survey (List 2): All PWSs serving more than 100,000 people, a 

representative sample of 320 large PWSs serving 10,001 to 100,000 people, and a 

representative sample of 480 small PWSs serving 10,000 or fewer people will monitor for 

seven chemicals contaminants. 

	 Pre-Screen Testing (List 3): Two viruses and related pathogen indicators (i.e., total 

coliforms, E. coli, bacteriophage, Enterococci, and aerobic spores) will be monitored at a 

representative selection of 800 undisinfected ground water PWSs serving 1,000 or fewer 

people. The virus monitoring will take place in sensitive hydrogeological areas (e.g., 

karst or fractured bedrock). 

Consistent with UCMR 1 and UCMR 2, EPA will manage and fund the UCMR 3 monitoring at 

small systems. 

All laboratories conducting analyses for UCMR 3 List 1 and List 2 contaminants must receive 

EPA approval to perform those analyses (see “UCMR 3 Laboratory Approval Requirements and 

Information Document” for details of EPA’s UCMR laboratory approval program). Pre-Screen 

Testing (List 3) analyses for viruses and indicators are organized and paid for by EPA through 

direct contracts with microbiology laboratories. The List 3 laboratories are subject to a laboratory 

approval process as part of their direct contracts with EPA. 

What are the major differences between the UCMR 3 proposed rule and final rule? 

Key revisions, relative to the March 2011 proposed rule, are as follows: 

 Chromium-6 and total chromium were added to the final contaminants list; 

 Sec-butylbenzene and n-propylbenzene were removed from the final contaminants list; 

 Monitoring of hormones was moved from Assessment Monitoring (List 1) to Screening 

Survey (List 2); 

 PWSs are required to report zip codes only for the customers they serve (zip codes 

associated with each sampling point will not be required); 

 The laboratory reporting timeframe is now 120 days after sample collection (same as 

earlier UCMRs); and 

 The PWS reporting timeframe is now 60 days after laboratories post data (same as earlier 

UCMRs). 

EPA 815-R-12-001 Page 3 of 5	 April 2012 
How did EPA select these contaminants? 

EPA selected the contaminants that will be monitored through a process that included a review 

of EPA's Contaminant Candidate List, which highlights priority contaminants that need 

additional research to support future drinking water regulations. The contaminants on the list are 

known or anticipated to occur in public water systems but are not addressed by existing national 

drinking water regulations. Additional contaminants of concern were selected based on current 

occurrence research and health-risk factors. 

What are the major differences between UCMR 2 and 3? 

This proposed rule (UCMR 3) revises the previous rule (UCMR 2) as follows: it updates the list 

of contaminants to be monitored; it provides information on how many systems will be required 

to monitor and where they are required to monitor (typically just after treatment and, in the case 

of several contaminants, in the distribution system); it identifies the analytical methods to be 

used; and it makes minor modifications to the requirements based on our experience 

implementing UCMR 1 and UCMR 2. 

What is the cost of the regulation? 

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

2012-2016, is approximately $17.45 million. The total estimated annual costs are described in 

Exhibit 2. 

The final rule applies to PWSs and the states. Non-labor costs will be incurred primarily by EPA 

and large PWSs. They include the cost of shipping samples to laboratories and the cost of the 

actual laboratory analyses. Labor costs pertain to PWSs, states and EPA. These costs include 

activities such as reading the regulation, notifying PWSs selected to participate, collecting 

samples, reviewing data, reporting, and keeping records. EPA expects that states will incur only 

labor costs associated with voluntary assistance with UCMR 3 implementation. Since state 

participation will be voluntary, level of effort will vary depending on their individual agreements 

with EPA. 

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 funding all costs 

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

monitoring for chemicals will only incur labor costs, which are attributed to the labor required 

for reading about their requirements and collecting samples. Small systems participating in virus 

monitoring will incur even lower labor costs since EPA contractors will collect the samples, 

record and report the data (because of the complexity of the sampling techniques). 

EPA 815-R-12-001 Page 4 of 5 April 2012 
EPA 815-R-12-001 Page 5 of 5 April 2012 

Exhibit 2: National Estimated Annual Cost of UCMR 3 (2012-2016)

Avg. Annual 

Respondent Cost. All 

Respondents 

(2012-2016) 

Small Systems (25-10,000), including labor only, non-labor costs paid for by $0.066 m

EPA 

Large Systems (10,001-100,000), including labor and non-labor costs $9.55 m

Very Large Systems (100,001 and greater), including labor and non-labor $2.94 m

costs 

States, including labor costs related to implementation coordination $0.75 m

EPA, including labor for implementation, non-labor for small system testing $4.14 m

AVERAGE ANNUAL NATIONAL TOTAL $17.45 m

How can I get additional information? 

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

http://water.epa.gov/lawsregs/rulesregs/sdwa/ucmr/ucmr3/index.cfm. 

You may also contact the Safe Drinking Water Hotline at (800) 426-4791 or 

http://water.epa.gov/drink/contact.cfm.