© 2025 American Dental Association l 89
Fluoridation Facts
55. Does fluoride at levels used in water fluoridation corrode glass,
concrete, or other surfaces in water plants?
Answer
No. A correctly engineered and maintained system will not result in damage to the water plant.
Fact
Fluorosilicic acid in a concentrated form can be corrosive if not correctly handled. The concentrated
fluorosilicic acid is 75% water and 25% fluorosilicic acid. Up to 1% of the fluorosilicic acid can be other
acids, including hydrogen fluoride. Hydrogen fluoride is volatile near room temperature, so it will
evaporate from the solution if the system is not properly engineered and maintained. The evaporation
process occurs at an extremely slow rate. Less than 1% of fluorosilicic acid will be lost over a month
from the evaporation of hydrogen fluoride. However, only a small release of hydrogen fluoride can be
very corrosive to concrete, glass, and electrical components.89
If a water system is reporting problems with corrosion from evaporating hydrogen fluoride in the
storage room or fluoride handling room (i.e., the glass in the facility has become “frosted”), there is a
leak in the conveyance piping. The storage tank and other locations in the fluorosilicic acid feed system
may not be sealed or correctly vented and hydrogen fluoride gas can be released (leaked) at those
points. The storage, handling, and feed systems of all fluoride products should be vented to the outside
of the building and the system and piping should be pressure tested (low pressure is sufficient) to
identify possible locations of leaks. Leaks should be promptly corrected.89
With no system leaks and proper venting to outside the building, there will be no corrosion problems.89
56. Does fluoridated water harm the environment?
Answer
No. Scientific evidence supports the fluoridation of public water supplies as safe for the
environment and beneficial for people.
Fact
Fluoride occurs naturally in the environment and is the 13th most abundant element in the Earth’s
crust. It is found naturally in all water sources, with typical concentrations as noted here.72,387
Rain—0.01 to 0.08 mg/L
Streams and lakes—generally 0.03 to 0.3 mg/L can be 200 mg/L in high-fluoride regions
Groundwaters—0.1 to 10 mg/L
Oceans and seawater—1.2 to 1.4 mg/L
Comprehensive reviews published in 2004 revealed no negative environmental impacts as a result
of water fluoridation.388,389 A 1990 study390 concluded that fluoridation has little or no impact on the
surrounding aquatic environment or soil. Historically, issues surrounding problems with fluoride and
the environment have involved incidents related to serious industrial pollution or accidents.390
There is no evidence that the recommended level of fluoride in drinking water has any adverse effect
on gardens or lawns.
Additional information regarding water fluoridation additives and engineering issues can be found
on the CDC’s fluoridation website, “Fluoridation Engineering and Operations.”91
Fluoridation Facts
55. Does fluoride at levels used in water fluoridation corrode glass,
concrete, or other surfaces in water plants?
Answer
No. A correctly engineered and maintained system will not result in damage to the water plant.
Fact
Fluorosilicic acid in a concentrated form can be corrosive if not correctly handled. The concentrated
fluorosilicic acid is 75% water and 25% fluorosilicic acid. Up to 1% of the fluorosilicic acid can be other
acids, including hydrogen fluoride. Hydrogen fluoride is volatile near room temperature, so it will
evaporate from the solution if the system is not properly engineered and maintained. The evaporation
process occurs at an extremely slow rate. Less than 1% of fluorosilicic acid will be lost over a month
from the evaporation of hydrogen fluoride. However, only a small release of hydrogen fluoride can be
very corrosive to concrete, glass, and electrical components.89
If a water system is reporting problems with corrosion from evaporating hydrogen fluoride in the
storage room or fluoride handling room (i.e., the glass in the facility has become “frosted”), there is a
leak in the conveyance piping. The storage tank and other locations in the fluorosilicic acid feed system
may not be sealed or correctly vented and hydrogen fluoride gas can be released (leaked) at those
points. The storage, handling, and feed systems of all fluoride products should be vented to the outside
of the building and the system and piping should be pressure tested (low pressure is sufficient) to
identify possible locations of leaks. Leaks should be promptly corrected.89
With no system leaks and proper venting to outside the building, there will be no corrosion problems.89
56. Does fluoridated water harm the environment?
Answer
No. Scientific evidence supports the fluoridation of public water supplies as safe for the
environment and beneficial for people.
Fact
Fluoride occurs naturally in the environment and is the 13th most abundant element in the Earth’s
crust. It is found naturally in all water sources, with typical concentrations as noted here.72,387
Rain—0.01 to 0.08 mg/L
Streams and lakes—generally 0.03 to 0.3 mg/L can be 200 mg/L in high-fluoride regions
Groundwaters—0.1 to 10 mg/L
Oceans and seawater—1.2 to 1.4 mg/L
Comprehensive reviews published in 2004 revealed no negative environmental impacts as a result
of water fluoridation.388,389 A 1990 study390 concluded that fluoridation has little or no impact on the
surrounding aquatic environment or soil. Historically, issues surrounding problems with fluoride and
the environment have involved incidents related to serious industrial pollution or accidents.390
There is no evidence that the recommended level of fluoride in drinking water has any adverse effect
on gardens or lawns.
Additional information regarding water fluoridation additives and engineering issues can be found
on the CDC’s fluoridation website, “Fluoridation Engineering and Operations.”91
