Monitoring Unregulated Drinking Water Contaminants

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 requires 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.


UCMR 3 analytical methods and contaminants

Assessment Monitoring (List 1 contaminants)

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

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 D5673-10Exit, Standard Methods 3125 (1997)Exit

cobalt

7440-48-4

1µg/L

EPTDS & DSMRT

EPA 200.8 Rev 5.4, ASTM D5673-10Exit, Standard Methods 3125 (1997)Exit

strontium

7440-24-6

0.3 µg/L

EPTDS & DSMRT

EPA 200.8 Rev 5.4, ASTM D5673-10Exit, Standard Methods 3125 (1997)Exit

chromium3

Not applicable.

0.2 µg/L

EPTDS & DSMRT

EPA 200.8 Rev 5.4, ASTM D5673-10Exit, Standard Methods 3125 (1997)Exit

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 monitor for seven List 2 contaminants during a 12-month period from January 2013 through December 2015.

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 participate in monitoring for two List 3 viruses during a 12-month period from January 2013 through December 2015.

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

  • Chemical Abstract Service (CAS) Registry Number
  • Sample points:
    • Entry points to the distribution system (EPTDS)
    • Distribution system maximum residence time (DSMRT)
  • 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.

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