Third Unregulated Contaminant Monitoring Rule

The 1996 Safe Drinking Water Act (SDWA) amendments require 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 third Unregulated Contaminant Monitoring Rule (UCMR 3) was published on May 2, 2012. UCMR 3 required monitoring for 30 contaminants (28 chemicals and two viruses) between 2013 and 2015 using analytical methods developed by EPA, consensus organizations or both. This monitoring provides a basis for future regulatory actions to protect public health.

• Federal Register Notice: Final Revisions to the UCMR 3 for Public Water Systems, May 2, 2012
• UCMR 3 Basic Information Fact Sheet
• EPA Approved Laboratories for UCMR 3

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UCMR 3 analytical methods and contaminants

• Assessment monitoring (List 1 contaminants)
• Screening survey (List 2 contaminants)
• Pre-screen testing (List 3 contaminants)
• Notes

Assessment Monitoring (List 1 contaminants)

All PWSs serving more than 10,000 people and 800 representative PWSs serving 10,000 or fewer people monitored for 21 List 1 contaminants during a 12-month period from January 2013 through December 2015.

• UCMR 3: Fact Sheet for Assessment Monitoring of List 1 Contaminants

Seven Volatile Organic Compounds

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
1,2,3-trichloropropane	96-18-4	0.03 µg/L	EPTDS	EPA 524.3
1,3-butadiene	106-99-0	0.1 µg/L	EPTDS	EPA 524.3
chloromethane (methyl chloride)	74-87-3	0.2 µg/L	EPTDS	EPA 524.3
1,1-dichloroethane	75-34-3	0.03 µg/L	EPTDS	EPA 524.3
bromomethane (methyl bromide)	74-83-9	0.2 µg/L	EPTDS	EPA 524.3
chlorodifluoromethane (HCFC-22)	75-45-6	0.08 µg/L	EPTDS	EPA 524.3
bromochloromethane (halon 1011)	74-97-5	0.06 µg/L	EPTDS	EPA 524.3

One Synthetic Organic Compound

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
1,4-dioxane	123-91-1	0.07 µg/L	EPTDS	EPA 522

Six Metals

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
vanadium	7440-62-2	0.2 µg/L	EPTDS & DSMRT	EPA 200.8 Rev 5.4
molybdenum	7439-98-7	1 µg/L	EPTDS & DSMRT	EPA 200.8 Rev 5.4, ASTM D5673-10, Standard Methods 3125 (1997)
cobalt	7440-48-4	1µg/L	EPTDS & DSMRT	EPA 200.8 Rev 5.4, ASTM D5673-10, Standard Methods 3125 (1997)
strontium	7440-24-6	0.3 µg/L	EPTDS & DSMRT	EPA 200.8 Rev 5.4, ASTM D5673-10, Standard Methods 3125 (1997)
chromium3	Not applicable.	0.2 µg/L	EPTDS & DSMRT	EPA 200.8 Rev 5.4, ASTM D5673-10, Standard Methods 3125 (1997)
chromium-6	18540-29-9	0.03 µg/L	EPTDS & DSMRT	EPA 218.7

One Oxyhalide Anion

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
chlorate	14866-68-3	20 µg/L	EPTDS & DSMRT	EPA 300.1, ASTM D6581-08, Standard Methods 4110D (1997)

Six Perfluorinated Compounds

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
perfluorooctanesulfonic acid (PFOS)	1763-23-1	0.04 µg/L	EPTDS	EPA 537 Rev 1.1
perfluorooctanoic acid (PFOA)	335-67-1	0.02 µg/L	EPTDS	EPA 537 Rev 1.1
perfluorononanoic acid (PFNA)	375-95-1	0.02 µg/L	EPTDS	EPA 537 Rev 1.1
perfluorohexanesulfonic acid (PFHxS)	355-46-4	0.03 µg/L	EPTDS	EPA 537 Rev 1.1
perfluoroheptanoic acid (PFHpA)	375-85-9	0.01 µg/L	EPTDS	EPA 537 Rev 1.1
perfluorobutanesulfonic acid (PFBS)	375-73-5	0.09 µg/L	EPTDS	EPA 537 Rev 1.1

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Screening Survey (List 2 contaminants)

All PWSs serving more than 100,000 people, 320 representative PWSs serving 10,001 to 100,000 people, and 480 representative PWSs serving 10,000 or fewer people monitored for seven List 2 contaminants during a 12-month period from January 2013 through December 2015.

• UCMR 3: Fact Sheet for Screening Survey of List 2 Contaminants

Seven Hormones

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
17-β-estradiol	50-28-2	0.0004 µg/L	EPTDS	EPA 539
17-α-ethynylestradiol (ethinyl estradiol)	57-63-6	0.0009 µg/L	EPTDS	EPA 539
16-α-hydroxyestradiol (estriol)	50-27-1	0.0008 µg/L	EPTDS	EPA 539
equilin	474-86-2	0.004 µg/L	EPTDS	EPA 539
estrone	53-16-7	0.002 µg/L	EPTDS	EPA 539
testosterone	58-22-0	0.0001 µg/L	EPTDS	EPA 539
4-androstene-3,17-dione	63-05-8	0.0003 µg/L	EPTDS	EPA 539

Pre-Screen Testing (List 3 contaminants)

EPA selected 800 representative PWSs that serve 1,000 or fewer people, do not disinfect, and have wells located in areas of karst or fractured bedrock to monitor for two List 3 viruses during a 12-month period from January 2013 through December 2015.

• UCMR 3: Fact Sheet for Pre-Screen Testing of List 3 Contaminants

Two Viruses

Contaminant	CAS Registry Number1	Minimum Reporting Level	Sampling Points2	Analytical Methods
enteroviruses	Not Applicable.	Not Applicable.	EPTDS	EPA 1615
noroviruses	Not Applicable.	Not Applicable.	EPTDS	EPA 1615

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Notes

1. Chemical Abstract Service (CAS) Registry Number
2. Sample points:
   • Entry points to the distribution system (EPTDS)
   • Distribution system maximum residence time (DSMRT)
3. Monitoring for total chromium in conjunction with UCMR 3 assessment monitoring is required under the authority provided in Section 1445(a)(1)(A) of the SDWA.