Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 1

Fact Sheet: Final Third Drinking Water 

Contaminant Candidate List (CCL 3) 

EPA has published a final list of contaminants which may require regulation under the Safe 

Drinking Water Act (SDWA). 

This final Contaminant Candidate List 3 (CCL 3) includes 104 chemicals or chemical groups and 

12 microbiological contaminants which are known or anticipated to occur in public water 

systems. The list includes chemicals used in commerce, pesticides, waterborne pathogens, 

disinfection byproducts, and biological toxins. The Agency evaluated approximately 7,500 

chemicals and microbes and selected 116 candidates for the CCL 3 that have the potential to 

present health risks through drinking water exposure. 

You can find more information on the CCL on EPA’s website at 

www.epa.gov/safewater/ccl/index.html

Questions and Answers

What is the drinking water CCL?

The drinking water CCL is a list developed by EPA that identifies priority contaminants for 

regulatory decision making and information collection. The contaminants on the list are known 

or anticipated to occur in public water systems and may require regulation. However, they are 

currently unregulated by existing national primary drinking water regulations. 

How often is the CCL published?

The Safe Drinking Water Act directs EPA to publish a CCL every five years. We published the 

first CCL in March 1998. We published the second CCL in February 2005. The draft CCL 3 

was published in February 2008. 

What contaminants are included on the CCL 3? 

The chemicals and microbes are listed on the attached table. 

 

Final Drinking Water Contaminant Candidate List 3 

 

Chemical Contaminants 

CASRN 

Common Name - 

Registry Name 

630206 

1,1,1,2-

Tetrachloroethane 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 2

75343 1,1-Dichloroethane 

96184 1,2,3-Trichloropropane 

106990 1,3-Butadiene 

99650 1,3-Dinitrobenzene 

123911 1,4-Dioxane 

57910 17 alpha-Estradiol 

71363 1-Butanol 

109864 2-Methoxyethanol 

107186 2-Propen-1-ol 

16655826 3-Hydroxycarbofuran 

101779 4,4'-Methylenedianiline 

30560191 Acephate 

75070 Acetaldehyde 

60355 Acetamide 

34256821 Acetochlor 

187022113 

Acetochlor 

ethanesulfonic acid 

(ESA) 

184992444 

Acetochlor oxanilic 

acid (OA) 

107028 Acrolein 

142363539 

Alachlor ethanesulfonic 

acid (ESA) 

171262172 

Alachlor oxanilic acid 

(OA) 

319846 

alphaHexachlorocyclohexan

e 

62533 Aniline 

741582 Bensulide 

100447 Benzyl chloride 

25013165 

Butylated 

hydroxyanisole 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 3

133062 Captan 

14866683 Chlorate 

74873 

Chloromethane (Methyl 

chloride) 

110429624 Clethodim 

7440484 Cobalt 

80159 Cumene hydroperoxide 

NA Cyanotoxins 

141662 Dicrotophos 

55290647 Dimethipin 

60515 Dimethoate 

298044 Disulfoton 

330541 Diuron 

517099 Equilenin 

474862 Equilin 

114078 Erythromycin 

50282 

Estradiol (17-beta 

estradiol) 

50271 Estriol 

53167 Estrone 

57636 

Ethinyl Estradiol (17-

alpha Ethynyl 

Estradiol) 

13194484 Ethoprop 

107211 Ethylene glycol 

75218 Ethylene oxide 

96457 Ethylene thiourea 

22224926 Fenamiphos 

50000 Formaldehyde 

7440564 Germanium 

74975 Halon 1011 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 4

(bromochloromethane) 

75456 HCFC-22 

110543 Hexane 

302012 Hydrazine 

72333 Mestranol 

10265926 Methamidophos 

67561 Methanol 

74839 

Methyl bromide 

(Bromomethane) 

1634044 Methyl tert-butyl ether 

51218452 Metolachlor 

171118095 

Metolachlor 

ethanesulfonic acid 

(ESA) 

152019733 

Metolachlor oxanilic 

acid (OA) 

2212671 Molinate 

7439987 Molybdenum 

98953 Nitrobenzene 

55630 Nitroglycerin 

872504 

N-Methyl-2-

pyrrolidone 

55185 

N-Nitrosodiethylamine 

(NDEA) 

62759 

Nnitrosodimethylamine 

(NDMA) 

621647 

N-Nitroso-di-npropylamine (NDPA) 

86306 

NNitrosodiphenylamine 

930552 

N-nitrosopyrrolidine 

(NPYR) 

68224 

Norethindrone (19-

Norethisterone) 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 5

103651 n-Propylbenzene 

95534 o-Toluidine 

75569 Oxirane, methyl301122 Oxydemeton-methyl 

42874033 Oxyfluorfen 

14797730 Perchlorate 

1763231 

Perfluorooctane 

sulfonic acid (PFOS) 

335671 

Perfluorooctanoic acid 

(PFOA) 

52645531 Permethrin 

41198087 Profenofos 

91225 Quinoline 

121824 RDX 

135988 sec-Butylbenzene 

7440246 Strontium 

107534963 Tebuconazole 

112410238 Tebufenozide 

13494809 Tellurium 

13071799 Terbufos 

56070167 Terbufos sulfone 

59669260 Thiodicarb 

23564058 Thiophanate-methyl 

26471625 Toluene diisocyanate 

78488 Tribufos 

121448 Triethylamine 

76879 

Triphenyltin hydroxide 

(TPTH) 

51796 Urethane 

7440622 Vanadium 

50471448 Vinclozolin 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 6

137304 Ziram 

Microbial Contaminants 

Adenovirus 

Caliciviruses 

Campylobacter jejuni 

Enterovirus 

Escherichia coli (0157)

Helicobacter pylori 

Hepatitis A virus 

Legionella pneumophila 

Mycobacterium avium 

Naegleria fowleri 

Salmonella enterica 

Shigella sonnei 

What approach did EPA use to list contaminants on the CCL? 

In developing the CCL 3, the Agency implemented a different process from that used for CCL 1 

and CCL 2. This new process builds on evaluations from previous CCLs and was based on 

substantial expert input and recommendations from various groups, including the National 

Academy of Science’s National Research Council (NRC), the National Drinking Water Advisory 

Council (NDWAC), and the Science Advisory Board (SAB). 

The Agency considered the best available health effects and occurrence data and information to 

evaluate unregulated contaminants. EPA evaluated data for chemicals identified in Superfund, 

registered pesticides, chemicals detected in drinking water or source waters, chemicals released 

to the environment, or high production commercial chemicals. The Agency also evaluated 

human pathogens for their potential to cause waterborne disease through drinking water 

exposure. 

EPA used a multi-step CCL process to identify contaminants for inclusion on the CCL 3. The 

key steps EPA took to develop the CCL 3 include: 

1) Identifying a broad universe of potential drinking water contaminants (called the 

“CCL Universe”). EPA evaluated 284 data sources that may identify potential chemical 

and microbial contaminants and selected a set of approximately 7,500 contaminants from 

these data sources for initial consideration. 

2) Applying screening criteria to the CCL universe to identify those contaminants that 

should be further evaluated (the preliminary CCL or PCCL) based on a contaminant’s 

potential to occur in public water systems and the potential for public health concern. 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 7

3) Identifying contaminants from the PCCL to include on the CCL based on more detailed 

evaluation of occurrence and health effects and expert judgment applied in a transparent, 

reproducible manner. 

4) Incorporating public input and expert review in the CCL process. 

EPA sought public input by asking for nominations of contaminants to consider for the CCL in 

October 2006 and incorporated these nominations into the three key steps discussed above. EPA 

also convened several expert panels to obtain review and input on the processes used to identify 

the draft CCL and the CCL 3 itself. 

How did EPA consider public comments on the draft CCL 3? 

EPA published the draft CCL 3 FR notice in February 2008. In this FR notice, EPA solicited 

input from the public, and specifically requested comments on (1) the approach EPA used to 

create the list; (2) contaminants on the list; and (3) specific contaminants such as 

pharmaceuticals, perfluorinated compounds, and microbes. EPA reviewed all comments 

received on the draft CCL 3 and evaluated information provided by commenters in determining 

which contaminants to include on the final CCL 3. 

What changes were made from the draft CCL 3 to the final CCL 3?

Based on the Agency’s review of data and information collected during the comment period and 

new available data, the Agency made these changes from the draft to the final CCL 3: 

• Removed 2 pesticides (ethion and nitrofen) because the registrations were cancelled 

and available data indicates they are unlikely to appear in drinking water sources. 

• Added 10 pharmaceuticals; one antibiotic (erythromycin) and nine hormones (17 

alpha-estradiol, 17-beta estradiol, equilenin, equilin, estriol, estrone, ethinyl estradiol, 

mestranol, and norethindrone) based on new health effects and occurrence data in 

ambient water. 

• Added 2 disinfection by-products (bromochloromethane (Halon1011) and chlorate) 

based on new health effects and occurrence data. 

• Added perfluorooctane sulfonate (PFOS) based on new health effects and occurrence 

data in public water systems. 

• Removed 2 microbes (Vibrio cholerae and Entamoeba histolytica) because the 

Agency decided to only use waterborne disease outbreak data more recent than 

January 1991. 

• Added 3 microbes to the final CCL 3 (Mycobacterium avium, Enterovirus and 

Adenovirus). Mycobacterium avium was added to the list based on the Agency’s reevaluation of its health effects. Enterovirus and Adenovirus were added to the list 

based on changes to the selection criteria and because the Agency used waterborne 

disease outbreak data more recent than January 1991. 
Office of Water (4607M) EPA EPA 815F09001 September 2009 www.epa.gov/safewater 8

What happens to contaminants on the draft CCL 3? 

The purpose of the draft CCL 3 was to present the list of contaminants and seek comment on the 

list and various aspects of its development. The Agency sought comments on the process used to 

identify the draft CCL 3, the data used in the process, and on the individual contaminants 

included in the CCL 3. All comments submitted were considered in determining the final CCL3. 

What happens to contaminants on the final CCL 3? 

EPA will evaluate all the contaminants on the CCL 3 to determine which contaminants have 

sufficient information to allow the Agency to make a regulatory determination. For those 

contaminants that lack sufficient information, EPA will encourage research to provide the 

information needed to determine whether to regulate the contaminant. 

Does the CCL impose any requirements on public water systems?

No. Publishing the CCL does not impose any requirements on public water systems. If EPA 

decided to regulate a contaminant on the list in the future, the Agency would start a separate 

rulemaking process with opportunity for public comment. 

What is a regulatory determination?

A regulatory determination is a formal decision on whether EPA should initiate a process to 

develop a national primary drinking water regulation for a specific contaminant. The law 

requires that EPA make regulatory determinations for at least five contaminants from the most 

recent CCL every five years. 

Where can I find more information about this notice and the CCL?

For information on the third CCL 3, please visit the EPA internet website, 

www.epa.gov/safewater/ccl/ccl3.html. For general information on drinking water, please visit 

the EPA Safewater website at www.epa.gov/safewater or contact the Safe Drinking Water 

Hotline at 1-800-426-4791. Local or international calls can reach the Hotline at 703-412-3330. 

The Safe Drinking Water Hotline is open Monday through Friday, excluding legal holidays, 

from 10:00 a.m. to 4:00 p.m., Eastern time.