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).

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 levelmaximum 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
	New information, but no revision recommended because:	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

Federal Register Notice
- National Primary Drinking Water Regulations; Announcement of the Results of EPA's Review of Existing Drinking Water Standards and Request for Public Comment and/or Information on Related Issues; Notice (March 29, 2010: Volume 75, Number 59)
Federal Register Notice (Extension of Comment Period)
- National Primary Drinking Water Regulations; Announcement of the Results of EPA's Review of Existing Drinking Water Standards and Request for Public Comment and/or Information on Related Issues; Extension of the Comment Period (June 1, 2010: Volume 75, Number 104)
Fact Sheet: Six-Year Review 2
- Read the Fact Sheet

US EPA

Six-Year Review 2 of Drinking Water Standards

On this page:

Summary of Six-Year Review 2 Results

Federal Register Notices and Fact Sheet

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