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Six-Year Review 2 of Drinking Water Standards

In March 2010, EPA announced the review results for the Agency’s second Six-Year Review (called Six-Year Review 2). After performing a detailed review of 71 national primary drinking water regulations (NPDWRs), the Agency found that 67 NPDWRs remain appropriate (i.e., do not need to be revised) and four NPDWRs were candidates for regulatory revision. These four NPDWRs identified as revision candidates included: 
  • acrylamide,
  • epichlorohydrin,
  • tetrachloroethylene and
  • trichloroethylene.

In addition to the 71 NPDWRs reviewed in detail for the Six-Year Review 2, fourteen other NPDWRs were included in the review but did not need a detailed review because of recent or ongoing regulatory actions (i.e., disinfection byproducts (DBPs), lead and copper, and microbials).

On this page:

 

Summary of Six-Year Review 2 Results

Learn more about the drinking water contaminants listed below

Summary of Review Outcomes Regulated Contaminants

1. For these compounds, there is no potential to change the maximum contaminant levelHelpmaximum contaminant levelThe highest level of a contaminant that is allowed in drinking water as delineated by the National Primary Drinking Water Regulations. These levels are based on consideration of health risks, technical feasibility of treatment, and cost-benefit analysis. (MCL) based on changes in analytical feasibility or there may be a potential change to the MCL based on analytical feasibility but any such change is unlikely to provide a meaningful opportunity to improve public health protection. Therefore, EPA chose to leave these in the ongoing health assessment category.

2. Note that a health assessment is in process but new analytical feasibility and treatment technology information may justify a revision.
No Detailed Technical Review Conducted During this Cycle Due to Recent or Ongoing Regulatory Action (14 NPDWRs) Bromate
Chloramines
Chlorine
Chlorine dioxide
Chlorite
Coliform
Copper
Cryptosporidium
Giardia lamblia
Haloacetic acids
Lead
Legionella
Total Trihalomethanes
Viruses
Not Appropriate for Revision at this Time Health effects assessment in process or potential nominee for an assessment (32 NPDWRs) Alpha particles (or emitters)1
Antimony
Arsenic
Asbestos
Benzo(a)pyrene1
Beryllium
Beta particles and photon emitters1
Cadmium
Carbon tetrachloride1
Chromium
Cyanide
1,2-Dichlorobenzene
1,4-Dichlorobenzene
1,2-Dichloroethane1
cis-1,2-Dichloroethylene
trans-1,2-Dichloroethylene
Dichloromethane1
Di(2-ethylhexyl)adipate1
Di(2-ethylhexyl)phthalate1
Ethylbenzene
Fluoride
Nitrate
Nitrite
Pentachlorophenol1
Polychlorinated biphenyls (PCBs)1
Radiums1
Selenium
Styrene
2,3,7,8-TCDD (dioxin)1
Thallium
1,2,4-Trichlorobenzene
Uranium
NPDWR remains appropriate after data/information review(8 NPDWRs) Dalapon
Dinoseb
Endrin
Ethylene Dibromide (EDB)
Mercury (inorganic)
Methoxychlor
Monochlorobenzene (chlorobenzene)
2,4,5-Trichorophenoxy-propionic acid (2,4,5-TP)
New information, but no revision recommended because: Low priority
(24 NPDWRs)
Alachlor
Barium
Benzene
Chlordane
1,2-Dibromo-3-chloropropane (DBCP)
1,1-Dichloroethylene
1,2-Dichloropropane
2,4-Dichlorophenoxyacetic acid (2,4-D)
Diquat
Endothall
Glyphosate
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Hexachlorocyclopentadiene
Lindane
Oxamyl
Picloram
Toluene
Toxaphene
1,1,1-Trichloroethane
1,1,2-Trichloroethane
Xylenes
Vinyl chloride

Emerging information or data gaps
(3 NPDWRs)

Atrazine
Carbofuran
Simazine
Candidate for Revision Based on new information (4 NPDWRs) Acrylamide2
Epichlorohydrin
Tetrachloroethylene (PCE)2
Trichloroethylene (TCE)2

Federal Register Notices and Fact Sheet


Support Documents and Occurrence Data for EPA's Second Six-Year Review of Existing Drinking Water Standards