© 2025 American Dental Association l 39
Fluoridation Facts
19. Why did the USPHS issue a report in 2015 recommending 0.7 mg/L
as the optimal level for fluoride in drinking water for all temperature
zones in the United States?
Answer
The USPHS updated and replaced its 1962 Drinking Water Standards related to community water
fluoridation to set a single value of 0.7 mg/L as the optimal concentration of fluoride in drinking
water for the whole country. This concentration provides the best balance of protection from tooth
decay while limiting the risk of dental fluorosis.196
Fact
The previous USPHS recommendations for optimal fluoride concentrations were based on average
ambient air temperatures of geographic areas and ranged from 0.7–1.2 mg/L. In 2011, the HHS
issued a notice of intent in the Federal Register196 proposing that all US community water systems
adjust the amount of fluoride to 0.7 mg/L to achieve an optimal fluoride level.
The new guidance was based on several considerations:
• Scientific evidence related to the effectiveness of water fluoridation on caries prevention
and control across all age groups.
• Fluoride in drinking water as one of several available fluoride sources.
• Trends in the prevalence and severity of dental fluorosis.
• Recent evidence on fluid intake in children across various ambient air temperatures.
As part of the process leading to the notice of intent, the HHS convened a federal interdepartmental,
interagency panel of scientists to review the scientific evidence relevant to the 1962 USPHS Drinking
Water Standards for fluoride concentrations in drinking water in the country and to update these
recommendations based on current science. Panelists included representatives from the NIH, EPA,
CDC, FDA, the Agency for Healthcare Research and Quality (AHRQ), the Office of the Assistant
Secretary for Health (OASH), and the US Department of Agriculture (USDA).196
A public comment period followed the publication of the notice of intent, during which time more
than 19,000 comments were received. The vast majority (more than 18,000) were variations on a
letter submitted by an organization opposing community water fluoridation. Comments received were
summarized and reported to the full federal panel. The panel then spent several years reviewing each
comment in light of the best available science. After completing its extensive review, the panel did not
alter the recommendation based on the following:
• Community water fluoridation remains an effective public health approach for delivering fluoride
to prevent tooth decay and is the most feasible and cost-effective strategy for reaching entire
communities.
• In addition to drinking water, other sources of fluoride exposure have contributed to the
prevention of dental caries and an increase in dental fluorosis prevalence.
• Caries preventive benefits can be achieved and the risk of dental fluorosis reduced at 0.7 mg/L.
• Recent data did not show a convincing relationship between water intake and outdoor air
temperature. Thus, recommendations for water fluoride concentrations that differ based
on outdoor temperature are no longer necessary.196
Fluoridation Facts
19. Why did the USPHS issue a report in 2015 recommending 0.7 mg/L
as the optimal level for fluoride in drinking water for all temperature
zones in the United States?
Answer
The USPHS updated and replaced its 1962 Drinking Water Standards related to community water
fluoridation to set a single value of 0.7 mg/L as the optimal concentration of fluoride in drinking
water for the whole country. This concentration provides the best balance of protection from tooth
decay while limiting the risk of dental fluorosis.196
Fact
The previous USPHS recommendations for optimal fluoride concentrations were based on average
ambient air temperatures of geographic areas and ranged from 0.7–1.2 mg/L. In 2011, the HHS
issued a notice of intent in the Federal Register196 proposing that all US community water systems
adjust the amount of fluoride to 0.7 mg/L to achieve an optimal fluoride level.
The new guidance was based on several considerations:
• Scientific evidence related to the effectiveness of water fluoridation on caries prevention
and control across all age groups.
• Fluoride in drinking water as one of several available fluoride sources.
• Trends in the prevalence and severity of dental fluorosis.
• Recent evidence on fluid intake in children across various ambient air temperatures.
As part of the process leading to the notice of intent, the HHS convened a federal interdepartmental,
interagency panel of scientists to review the scientific evidence relevant to the 1962 USPHS Drinking
Water Standards for fluoride concentrations in drinking water in the country and to update these
recommendations based on current science. Panelists included representatives from the NIH, EPA,
CDC, FDA, the Agency for Healthcare Research and Quality (AHRQ), the Office of the Assistant
Secretary for Health (OASH), and the US Department of Agriculture (USDA).196
A public comment period followed the publication of the notice of intent, during which time more
than 19,000 comments were received. The vast majority (more than 18,000) were variations on a
letter submitted by an organization opposing community water fluoridation. Comments received were
summarized and reported to the full federal panel. The panel then spent several years reviewing each
comment in light of the best available science. After completing its extensive review, the panel did not
alter the recommendation based on the following:
• Community water fluoridation remains an effective public health approach for delivering fluoride
to prevent tooth decay and is the most feasible and cost-effective strategy for reaching entire
communities.
• In addition to drinking water, other sources of fluoride exposure have contributed to the
prevention of dental caries and an increase in dental fluorosis prevalence.
• Caries preventive benefits can be achieved and the risk of dental fluorosis reduced at 0.7 mg/L.
• Recent data did not show a convincing relationship between water intake and outdoor air
temperature. Thus, recommendations for water fluoride concentrations that differ based
on outdoor temperature are no longer necessary.196
