Office of Water (4607M) EPA 815-F-11-003 February 2011 water.epa.gov/drink

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Fact Sheet: Final Regulatory 

Determination for Perchlorate

EPA has decided to regulate perchlorate under the Safe Drinking Water Act (SDWA). The 

science that has lead to this decision has been peer reviewed by independent scientists and 

public health experts including the National Academies of Science. 

This decision is the first time EPA has decided to regulate a substance from the Contaminant 

Candidate List required by the 1996 Amendments to the Safe Drinking Water Act. This decision 

reverses a 2008 preliminary determination and considers input from almost 39,000 public

commenters.

Questions and Answers

What is perchlorate?

Perchlorate is both a naturally occurring and man-made chemical that is used to produce rocket 

fuel, fireworks, flares and explosives. Perchlorate can also be present in bleach and in some 

fertilizers.

Why did EPA decide to regulate perchlorate? 

EPA has determined that perchlorate meets SDWA’s thee criteria for regulating a contaminant. 

1) Perchlorate may have adverse health effects because scientific research indicates that 

perchlorate can disrupt the thyroid’s ability to produce hormones needed for normal growth and 

development. 2)There is a substantial likelihood that perchlorate occurs with frequency at 

levels of health concern in public water systems because monitoring data show over four 

percent of public water systems have detected perchlorate, and 3.) There is a meaningful 

opportunity for health risk reduction for the between 5.2 and 16.6 million people who may be 

served drinking water containing perchlorate. 

Is EPA requiring public water systems to take action now to address perchlorate?

No, this action notifies interested parties of EPA’s determination to regulate perchlorate, but 

imposes no requirements on public water systems at this time. However, this action initiates the 

process to develop a national primary drinking water regulation (NPDWR) for perchlorate.

What happens next?

EPA will continue to evaluate the science on perchlorate health effects and occurrence in 

developing a proposed NPDWR for perchlorate. EPA will also now begin to evaluate the 

feasibility and affordability of treatment technologies to remove perchlorate and will examine the 

costs and benefits of potential standards. EPA will consult with our Science Advisory Board and 

with the National Drinking Water Advisory Council. EPA intends to publish the proposed 

regulation and analyses for public review and comment within 24 months. EPA will consider the 

public comments and expects to promulgate a final regulation within 18 months of the proposal.
Office of Water (4607M) EPA 815-F-11-003 February 2011 water.epa.gov/drink

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What is a regulatory determination?

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

process to develop a national primary drinking water regulation (NPDWR) for a specific 

contaminant. 

EPA identifies contaminants for decisions on whether drinking water regulations are needed and 

for research prioritization with the drinking water Contaminant Candidate List (CCL). The 

contaminants on the list are known or anticipated to occur in public water systems. However, 

they are currently not regulated with a national primary drinking water regulation. Under the 

Safe Drinking Water Act, EPA publishes a CCL every five years. EPA then makes regulatory 

determinations from the list of contaminants. EPA included perchlorate on the first, second, and 

third CCLs that were published in the Federal Register on March 2, 1998, February 24, 2005, 

and October 8, 2009, respectively.

Where can I find more information about this notice and the Perchlorate Regulatory 

Determination?

For information on the regulatory determinations for the second CCL, please visit 

http://www.epa.gov/safewater/ccl/reg_determine2.html. For general information on drinking 

water, please visit the EPA Safewater Web site at www.epa.gov/safewater or contact the Safe 

Drinking Water Hotline at 1-800-426-4791. 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. 

For information on perchlorate, please visit 

http://water.epa.gov/drink/contaminants/unregulated/perchlorate.cfm.