Fluoridation | Santa Clara Valley Water
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(Updated August 2019)

Valley Water began fluoridation in 2016, but many areas of the county remain unfluoridated.

NOTE: The information provided is based on approximate water service areas; please check with your water retailer for the most accurate fluoride concentration in your drinking water.

Thousands of research studies and more than 70 years of experience have demonstrated that fluoridating public drinking water is not only safe and effective, it is the best method of improving oral health in a community. In fact, the Centers for Disease Control and Prevention (CDC) recognized drinking water fluoridation as one of the 10 great major public health achievements of the 20th century. [1]

Although tooth decay can be prevented, it still affects more children in the United States than any other chronic infectious disease. [2]

Fluoridation of drinking water, proven to reduce tooth decay in both children and adults, is endorsed by the American Dental Association (ADA). Studies prove water fluoridation continues to be effective in reducing tooth decay by 20 to 40%, even in an era with widespread availability of fluoride from other sources. [3,4]

Along with the CDC and the ADA, the American Medical Association, the American Cancer Society, the American Academy of Pediatrics, the National Institutes of Health, the National Parents-Teachers Association, and the World Health Organization support drinking water fluoridation.

Based on these benefits, Valley Water’s Board of Directors decided in November 2011 to provide optimal levels of fluoride at its three water treatment plants. Implementation of fluoridation was completed in December 2016 for eastern Santa Clara County, and is expected to be completed in 2022 for western Santa Clara County. 

Despite fluoridation's proven record, many consumers may not be familiar with its benefits or may be concerned about adding a chemical to their drinking water.

  • The answers to some of the more frequently asked questions about fluoride are provided below

To express fluoride related comments or concern, please call the Valley Water fluoride information line at 1 (408) 630-2020. For questions on drinking water safety, members of the public are encouraged to contact Drinking Water Toxicologist Bruce A. Macler, PhD, of the U.S. EPA, Region 9, at 1 (415) 972-3569.

Comments or questions directed to Valley Water can be submitted through our Access Valley Water system.

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Frequently asked questions 

Q1. What is fluoride?  
Fluoride is the electrically charged atom (or "ion") that makes up the naturally occurring element fluorine. Although fluoride comes from fluorine, its properties are very different, just like chloride in common table salt is very different from chlorine. Most sources of drinking water contain some naturally occurring fluoride.

Q2. What is fluoridation? 
Fluoridation is the addition of fluoride to a drinking water supply so that it contains the level recommended for optimal protection against tooth decay.

Q3. Why is Valley Water fluoridating its water supplies?  
Community water fluoridation is supported by most major national and international health service organizations. Supporters include: the American Dental Association, American Medical Association, American Academy of Pediatric Dentistry, U.S. Centers for Disease Control and Prevention, and the World Health Organization. After hearing information from many sides of the issue over several months, in 2011 Valley Water’s Board of Directors voted to fluoridate at the district’s three water treatment plants.

As a drinking water wholesaler, Valley Water is exempt from the state law which mandates fluoridation; however, local health officials have advocated for large-scale fluoridation to be applied in order to maximize the public health benefits and minimize the cost of treating municipal water supplies. Fluoridation at our three drinking water treatment plants would be the most cost-effective means of providing this proven health benefit to Santa Clara Valley.

Q4. How does fluoride protect teeth against tooth decay?  
Tooth enamel and the material underneath are made mostly of two common minerals--calcium and phosphate. Tooth decay occurs when acids produced by bacteria in the mouth dissolve or "demineralize" the teeth. Fluoride protects against tooth decay by slowing down or stopping demineralization, promoting "remineralization" and keeping the bacteria from producing too much acid.

According to the American Dental Association, during tooth formation, ingested fluorides become incorporated into tooth structures. Fluorides ingested regularly during the time when teeth are developing are deposited throughout the entire tooth surface and provide longer-lasting protection than those applied topically. Ingested fluorides are also present in saliva, which continually bathes the teeth providing a reservoir of fluoride that can be incorporated into the tooth surface to prevent decay. [5] 

Q5. What proof is there that fluoridated water prevents tooth decay? 
According to the American Dental Association, the effectiveness of water fluoridation has been documented in scientific literature for more than 70 years [6]. Thousands of studies have been done which continue to prove fluoride’s effectiveness in decay reduction.

A 1987 study of 40,000 schoolchildren showed that the decay rate was 25% lower in children with continuous residence in fluoridated communities when the data was adjusted to control for fluoride exposure from supplements and topical treatments. [7] 

In 1993, the results of 113 published studies in 23 countries were analyzed. The analysis concluded that “community water fluoridation is one of the most successful public health disease prevention programs ever initiated. It has the potential to benefit all age groups and all socioeconomic strata, including the lowest, which has the highest caries prevalence and is least able to afford preventive and restorative services. Community water fluoridation is also the most cost-effective of all community-based caries preventive methods.” [8] 

In 2015, the U.S. Department of Health and Human Services (HHS) reviewed all available evidence and recommended community water be fluoridated throughout the USA, where feasible, at an optimal concentration of 0.7 parts per million. [9] 

Q6. If I use a fluoridated toothpaste, am I already getting enough fluoride to protect against decay?  
Community water fluoridation provides crucial, added protection against tooth decay, even when both fluoride products and treatments are widely available. Given the widespread use of fluoride toothpaste today, fluoridated water is still necessary. [10] Decay reductions are greatest where water fluoridation is available in addition to topical fluorides, such as fluoride toothpaste and fluoride rinses. The ADA concludes that “even in an era with widespread availability of fluoride from other sources, studies show that community water fluoridation prevents at least 25% of tooth decay in children and adults throughout the life span.” [11] 

Q7. How much fluoride is used to treat drinking water supplies?  
On April 27, 2015, the U.S. Department of Health and Human Services (HHS) finalized its recommendation for an optimal drinking water fluoride level of 0.7 milligrams per liter (mg/L) or parts per million (ppm). Following this announcement, California’s Division of Drinking Water (DDW) posted an advisory stating that public water systems practicing fluoridation could immediately implement the recommended optimal level of 0.7 ppm with a control range of 0.6 ppm to 1.2 ppm. [12]

Q8. How much fluoride is in my drinking water?  
Valley Water’s drinking water contains natural levels of fluoride of about 0.1 milligrams per liter (mg/L) or parts per million (ppm). Since beginning fluoridation in 2016, Valley Water’s east county drinking water fluoride levels average about 0.7 ppm. However, since Valley Water is a drinking water wholesaler, and many retail water agencies in Santa Clara County have more than one source of supply, the water delivered to your home may not come from Valley Water. Interested consumers should contact their water provider to find out how much fluoride, if any, is likely to be in their tap water.

Q9. What chemical is Valley Water using to fluoridate its supplies?  
While there are three chemicals commonly used to fluoridate municipal drinking water, Valley Water selected fluorosilicic acid as the most cost-effective bulk chemical to be used in the district's treatment processes. This is the most commonly used fluoride additive by large water systems and is approved for use by the State Water Resources Control Board’s Division of Drinking Water (DDW), who regulates the drinking water that we serve. The selected fluorosilicic acid is certified for compliance with the American National Standards Institute (ANSI) and National Sanitation Foundation (NSF) Standard 60. ANSI/NSF Standard 60 ensures that chemicals used to treat drinking water do not contribute contaminants to the water that could cause adverse health effects.

Q10. Once Valley Water adds fluoride at all its treatment plants, do its retailers still need to treat their supplies?  
Any agency relying on Valley Water for 100 percent of its treated drinking water will benefit from fully optimized fluoride concentrations. If a water system blends Valley Water supplies with other non-fluoridated supplies, additional fluoride treatment would be necessary within its system to maintain optimal fluoride levels. If no additional fluoride is added in the blended system, fewer overall health benefits would be provided.

Q11. Is fluoride harmful to my health?  
There have been literally hundreds, if not thousands, of studies that have looked at whether fluoride in drinking water is harmful to human health. These studies have looked at whether there is a link between fluoride and cancer, bone fractures as well as adverse effects on the immune system, kidneys, digestive system and reproductive system. The American Dental Association concludes that “the overwhelming weight of scientific evidence supports the safety of community water fluoridation” [13] 

That doesn't mean that no studies have ever shown a link between an adverse health effect and fluoride in drinking water. Some of the studies that suggested a link looked at drinking water with fluoride levels 10 or more times higher than what will be in water fluoridated by Valley Water or recommended by public health officials. Other studies, when repeated, did not find any link, were inconclusive or suggested that fluoride actually reduced the rate of certain diseases. It is important to look at the whole body of scientific evidence and the quality of the studies. Fortunately, many studies have been performed, and the conclusions of the ADA are based on a review of the many studies that have been undertaken.

In 2015, the Water Research Foundation published “State of the Science: Community Water Fluoridation.” Among the conclusions was this: “Concerns with community water fluoridation (CWF) and fluoride exposure have been examined based on the latest science. Many concerns with CWF were health related. Each of these concerns was addressed and a balance of scientific studies showed that none of these issues poses a risk to public health at CWF levels” (p. 26) [14] 

Q12. How does Valley Water plan to guard against over-feeding fluoride into its water supply?  
To prevent chemical overfeed, Valley Water monitors its treatment plant water on a continuous basis using on-line analyzers, and verifies the accuracy of these analyzers with weekly "grab" samples and monthly standard calibrations.

Q13. I heard that fluoride can cause teeth to become discolored or pitted, is that true?  
Dental fluorosis is a condition that causes changes in the appearance of tooth enamel. It may result when children regularly consume fluoride during the teeth-forming years, age 8 and younger. Most dental fluorosis in the U.S. is very mild to mild, appearing as white spots on the tooth surface that may be barely noticeable and do not affect dental function. Moderate and severe forms of dental fluorosis, which are far less common, cause more extensive enamel changes. In the rare, severe form, pits may form in the teeth. The severe form hardly ever occurs in communities where the level of fluoride in water is less than 2 milligrams per liter. [15] 

Q14. Should I give fluoridated water to my infant?  
The American Dental Association states that “it is safe to use fluoridated water to mix infant formula. If your baby is primarily fed infant formula, using fluoridated water might increase the chance for mild enamel fluorosis, but enamel fluorosis does not affect the health of your child or the health of your child’s teeth. Parents and caregivers are encouraged to talk to their dentists about what’s best for their child.” The ADA offers the following recommendations to decrease the chances of your child’s teeth developing fluorosis:

For infants,

  • You can breastfeed your child. The American Academy of Pediatrics recommends human milk for all infants (except for the few for whom breastfeeding is determined to be harmful). Breast milk is very low in fluoride. Nursing mothers or pregnant women who drink fluoridated water do not pass on significant amounts of fluoride to their child. 
  • You can use ready-to-feed formula. This type of formula contains little fluoride and does not contribute significantly to the development of mild dental fluorosis.
  • You can use powdered or liquid concentrate formula mixed with water that either is fluoride-free or has low concentrations of fluoride. These bottled waters are labeled as de-ionized, purified, demineralized, or distilled.

Parents and caregivers should consult with their pediatrician or family physician on the most appropriate formula for their child.

The chance of development of fluorosis exists through about eight years of age when the teeth are still forming under the gums.  Fluoride intake from other sources during this time such as toothpaste and mouth rinse may also contribute to the chance of fluorosis for children living in non-fluoridated and fluoridated communities. [16]

Similarly, the Centers for Disease Control and Prevention notes that “Yes, you can use fluoridated water for preparing infant formula. However, if your child is only consuming infant formula mixed with fluoridated water, there may be an increased chance for mild dental fluorosis. To lessen this chance, parents can use low-fluoride bottled water some of the time to mix infant formula; these bottled waters are labeled as de-ionized, purified, demineralized, or distilled, and without any fluoride added after purification treatment.” [17] 

Q15. Will I miss the benefits from fluoridation if I drink bottled water, vended water or water from a "water store"? What about home filtration devices?  
If you mostly drink bottled water, water from vending machines or water from water stores, you may miss the benefits of an optimally fluoridated water supply. That's because all of these alternatives typically contain fluoride levels that are below the optimal level for prevention of tooth decay.

Q16. I still would rather not drink water that has fluoride added to it, what choices do I have?  
You have several choices. Many brands of bottled water contain some levels of fluoride. You can call the consumer information number on the bottle's label and ask about the level of fluoride and whether this level is naturally low. Other brands of bottled water take tap water and then further treat it. The additional treatment, if by reverse osmosis or distillation will remove a significant amount of both naturally occurring fluoride and any fluoride added through fluoridation. These bottled waters will say "purified" water on the label and should have very low levels of fluoride. Again, call the consumer service number on the bottle's label for more information about the level of fluoride.

If you are considering vended water or water from a water store, make sure the water has been treated by reverse osmosis or distillation. You can also use home treatment devices that are reverse osmosis systems or distillation units. For a list of state-certified devices, go to: http://www.waterboards.ca.gov/drinking_water/certlic/device/watertreatmentdevices.shtml. NSF International, a not-for-profit testing organization, also certifies certain reverse osmosis home treatment devices and distillation units for the reduction of fluoride. You can search online for NSF-certified products at: http://www.nsf.org/certified/DWTU/. Home filtration devices must be maintained according to the manufacturer's instructions to ensure their effectiveness.

Q17. Will fluoridated water harm my pets?  
No. According to the San Francisco Public Utilities Commission, “Fluoride in levels administered for drinking water is safe for humans and all animals. Over 50 years of research and experience have shown fluoridation at optimal levels does not harm people or the environment.” [18] 

Q18. Where can I get more information about fluoride? 
The ADA and CDC both have web sites that provide very good information about fluoride and fluoridation. Go to www.ada.org/fluoride.aspx or www.cdc.gov/fluoridation/.




  1. Centers for Disease Control and Prevention. Ten Great Public Health Achievements -- United States, 1900-1999. MMWR 1999;48(12):241-3.  Available at https://www.cdc.gov/mmwr/preview/mmwrhtml/00056796.htm  (accessed on August 23, 2019)
  2. Centers for Disease Control and Prevention. Water, Sanitation & Environmentally-related Hygiene. Hygiene-related Diseases - Dental Caries (Tooth Decay). https://www.cdc.gov/healthywater/hygiene/disease/dental_caries.html (accessed August 23, 2019)
  3. Slade GD, Grider WB, Maas WR, Sanders AE. Water Fluoridation and Dental Caries in U.S. Children and Adolescents. J Dent Res. 2018 Sep;97(10):1122-1128.  Available at https://www.ncbi.nlm.nih.gov/pubmed/29900806  (accessed on August 23, 2019)
  4. U.S. Department of Health and Human Services Federal Panel on Community Water Fluoridation. U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries. Public Health Rep. 2015;130(4):318-331. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547570/?report=classic (accessed on August 23, 2019)  
  5. American Dental Association. Oral Health Topics. Fluoride: Topical and Systemic Supplements. Key Points. https://www.ada.org/en/member-center/oral-health-topics/fluoride-topical-and-systemic-supplements (accessed on August 23, 2019)
  6. American Dental Association. Fluoridation Facts. 2018:5
  7. ADA 2005:13. Brunelle JA, Carlos JP. Recent trends in dental caries in U.S. children and the effect of water fluoridation. J Dent Res 1990;69(Spec Iss):723-7. Available at https://www.ncbi.nlm.nih.gov/pubmed/2312893 (Accessed on August 23, 2019)
  8. Ripa LW. A half-century of community water fluoridation in the United States: review and commentary. J Public Health Dent 1993;53(1):17-44. Available at https://www.ncbi.nlm.nih.gov/pubmed/8474047  (accessed on August 23, 2019)
  9. U.S. Department of Health and Human Services Federal Panel on Community Water Fluoridation. U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries. Public Health Rep. 2015;130(4):318-331. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547570/?report=classic (accessed on August 23, 2019)  
  10. Campaign for Dental Health. Is Using Fluoride Toothpaste Enough? https://ilikemyteeth.org/wp-content/uploads/2014/12/Is-Fluoride-Toothpaste-Enough.pdf (accessed August 23, 2019)
  11. American Dental Association. Fluoridation Facts. 2018:20.  
  12. California State Water Resources Control Board. Fluoridation by Public Water Systems. Available at https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Fluoridation.html (accessed August 22, 2019)
  13. American Dental Association. Fluoridation Facts. 2018:37
  14. Water Research Foundation. State of the Science: Community Water Fluoridation. Available at https://ilikemyteeth.org/water-research-foundation-supports-fluoridation/  (accessed on August 23, 2019)
  15. Centers for Disease Control and Prevention. Community Water Fluoridation. Fluorosis. Available at https://www.cdc.gov/fluoridation/faqs/dental_fluorosis/index.htm  (accessed on August 23, 2019)
  16. American Dental Association. Fluoridation FAQs. Available at https://www.ada.org/en/public-programs/advocating-for-the-public/fluoride-and-fluoridation/fluoridation-faq (accessed on August 23, 2019)
  17. Centers for Disease Control and Prevention. Community Water Fluoridation—Overview: Infant Formula and Fluorosis. Available at https://www.cdc.gov/fluoridation/faqs/infant-formula.html (accessed August 23, 2019).
  18. San Francisco Public Utilities Commission: Fluoridation. Available at https://www.sfwater.org/index.aspx?page=408 (accessed on August 23, 2019)