Private Well Water and Fluoride
This fact sheet addresses questions that consumers may have on fluoride
levels in groundwater from private wells.
How do I know if my water is from a public water system or a private
The U.S. Environmental Protection Agency defines a Public Water System as a
system that serves 25 or more people per day. If you have water service from
a well that has a limited delivery, such as to your house but not to your
neighbor’s house, then you likely have a private well.
What are the governmental regulations for private wells?
Although most U.S. households are connected to a public water system, the
U.S. Geological Survey report “Estimated
Use of Water in the United States in 2005” estimates that 14% of United
States residents rely on private wells that are not regulated by the EPA
Safe Drinking Water Act. In most states, private wells are not regulated by
governmental regulatory entities. Therefore, it is the responsibility of the
homeowner to know and understand the quality of the water from their well.
The U.S. Environmental Protection Agency suggests that all wells be tested
for quality once every three years since influences to well water quality
can change over time. Contact your public health office for their advice on
testing of private wells in your state or area. Additional information on
testing well water quality in private wells serving homes can be found on
Environmental Protection Agency Web site.
My home gets its water from a private well. What do I need to know
about fluoride and groundwater from a well?
Fluoride is present in virtually all waters at some level, and it is
important to know the fluoride content of your water, particularly if you
have children. A
Geological Survey study found that 4% of sampled wells had natural
fluoride levels above the EPA Secondary Maximum Contaminant Level (SMCL) of
2 mg/L. A smaller set of 1.2% of all wells exceeded the Maximum Contaminant
Level (MCL) of 4 mg/L. If you have a home well, the EPA recommends having a
sample of your water analyzed by a laboratory at least once every three
years. Check with your dentist, physician, or public health department to
learn how to have your home well water tested.
What should I do if the water from my well has less fluoride than
the recommended level of 0.7 mg/L? Can I add fluoride?
The recommended fluoride level in drinking water for good oral health is 0.7
mg/L (milligrams per liter). If fluoride levels in your drinking water are
lower than 0.7 mg/L, your child's dentist or pediatrician should evaluate
whether your child could benefit from daily fluoride supplements. (The
prescription dosage of fluoride supplements should be consistent with the
(PDF–431K) established by the American Dental Association (ADA) Council on
Scientific Affairs.) Their recommendation will depend on your child's risk
of developing tooth decay, as well as exposure to other sources of fluoride,
such as drinking water at school or daycare, and fluoride toothpaste. It is
not feasible to add fluoride to an individual residence’s well.
What should I do if the water from my well has fluoride levels
that are higher than the recommended level of 0.7 mg/L?
In some regions in the United States, community drinking water and
private wells can contain levels of naturally occurring fluoride that are
greater than the level recommended by the CDC for preventing tooth decay.
Consuming water with fluoride between 0.6 and 2.0 mg/L results in reduced
tooth decay, but consumption of water with fluoride exceeding 2.0 mg/L may
increase the potential for
The U.S. Environmental Protection Agency (EPA) currently has a
non-enforceable recommended guideline for fluoride of 2.0 mg/L to protect
against dental fluorosis. If your home is served by a private well that has
fluoride levels exceeding this recommended guideline, but lower than 4.0
mg/L, then it is best to provide children under 8 years of age with an
alternative water source, such as bottled water with a low fluoride content.
Continue to test your well water’s quality every three years as
recommended by EPA.
What should I do if my well water was measured as having too much
fluoride (level greater than 4 mg/L)?
It is unusual to have the fluoride content of water exceed 4 mg/L. If a
laboratory report indicates that you have such excessive fluoride content,
it is recommended that the water be retested. At least four samples should
be collected, a minimum of one week apart, and the results compared. If one
sample is above 4 mg/L and the other samples are less than 4 mg/L, then the
high value may have been an erroneous measurement. If all samples register
excessive levels greater than 4 mg/L, then you may want to consider
investigating alternate sources of water for drinking and cooking, or
installing a device to remove the fluoride from your home water source.
Physical contact with high fluoride content water, such as bathing or
dishwashing, is safe since fluoride does not pass through the skin.
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What are the health risks of consuming water with fluoride levels
greater than 4 mg/L?
Children aged 8 years and younger have an increased chance of developing
severe tooth dental fluorosis. Consumption over a lifetime may increase the
likelihood of bone fractures, and may result in skeletal fluorosis, a
painful or even crippling disease. The U.S. Environmental Protection Agency
has determined that safe exposure of fluoride is below 4 mg/L in drinking
water to avoid those effects.
Will using a home water filtration system take the fluoride out of my
Removal of fluoride from water is difficult. Most home point-of-use
treatment systems that are installed at single faucets use activated carbon
filtration, which does not remove the fluoride. Reverse osmosis point-of-use
devices can effectively remove fluoride, although the amount may vary given
individual circumstances. For a home point-of-use device to claim a
reduction in fluoride, it must meet National Sanitation Foundation (NSF)
Standard 58 criteria for fluoride removal. Standard 58 requires that a
device must achieve a 1.5 milligrams per liter (mg/L) concentration in the
product water if the original concentration was 8.0 mg/L, or approximately
80 percent removal. This percentage removal may not be consistent at lower
concentrations of fluoride. Check with the manufacturer of the individual
product for specific product information.
Fluoride is not released from water when it is boiled or frozen. One
exception would be a water distillation system. These systems heat water to
the boiling point and then collect water vapor as it evaporates. Water
distillation systems are typically used in laboratories. For home use, these
systems can be expensive and may present safety and maintenance concerns.
Can I use water with fluoride for preparing infant formula?
Yes, you can use well water for preparing infant formula. It is important,
however, to ensure that the well water has been recently tested to verify
safety. EPA suggests that well water should be tested a minimum of once
every three years for micro-organisms and other substances. In addition,
parents of young children should also have their well water tested for
For more information on private well testing, contact your local health
department or visit the
EPA Web site. Parents and caregivers should speak
with their pediatrician to review the results of the private well testing
and to determine if the well water should be boiled prior to mixing the
formula. If you are advised to boil the water, be sure to boil the water
only one time so that you don’t concentrate substances by the boiling
If your child is exclusively consuming infant formula reconstituted with
well water, and if that water contains fluoride, there is an increased
chance for dental fluorosis. To lessen this chance, parents can use
low-fluoride bottled water some of the time to mix infant formula; these
bottled water are labeled as de-ionized, purified, demineralized, or
distilled. For more information, see Overview: Infant Formula and Fluorosis.
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Page last reviewed: February 1, 2012
Page last modified: February 1, 2012
Division of Oral Health,
National Center for Chronic Disease Prevention and