What's on tap: Fluoride in drinking water


A naturally occurring mineral, fluoride is the 13th most abundant element on the Earth's crust. It occurs naturally in soil, water, foods, and several minerals. Its most common use today is for preventing tooth decay.


Fluoride is naturally present in low concentration in drinking water and is often added to municipal water systems. It's also naturally present in very low quantities in some foods and beverages including table wine (1.150 mg per 26.4 fl oz.), brewed black tea (0.884 mg per 8 fl oz.), seedless raisins (0.033 mg per 1.5 oz.), lamb (0.054 mg per 6 oz.), and carrots (0.002 mg per 2.5 oz.). Fluoridated water as a health treatment is a much-debated practice that dates back to a scientific discovery made in the 1940s. The National Cancer Institute explains, "scientists discovered that people who lived where drinking water supplies had naturally occurring fluoride levels of approximately 1 part fluoride per million parts water or greater had fewer dental caries (cavities) than people who lived where fluoride levels in drinking water were lower." A number of further studies confirmed this discovery, and "in 1945, Grand Rapids, Michigan, adjusted the fluoride content of its water supply to 1.0 ppm and thus became the first city to implement community water fluoridation."


Today, many city and municipal water systems add fluoride to their water in order to reduce tooth decay and cavities. Called "community water fluoridation", the practice is intended to support dental health every time you drink a glass of city water. And the Centers for Disease Control and Prevention (CDC) say it's working. "Given the dramatic decline in tooth decay during the past 70 years since community water fluoridation was initiated, the CDC named fluoridation of drinking water to prevent dental caries (tooth decay) as one of 10 great public health achievements of the 20th century." Other supporters of community water fluoridation include American Dental Association, American Academy of Pediatrics, U.S. Public Health Service, and World Health Organization.


While there is documented research to support the benefits of adding fluoride to drinking water, there have also been concerns about a connection between fluoridated water and cancer. The National Cancer Institute cites a number of studies that have found no evidence of fluoride causing cancer in humans. And while the American Cancer Society does not offer an official position or view on the subject, their website says, "the general consensus among the reviews done to date is that there is no strong evidence of a link between water fluoridation and cancer. However, several of the reviews noted that further studies are needed to clarify the possible link." Additional opposing views include concerns that fluoridation is an outdated method of mass medication, and that it's unnecessary and ineffective because its benefit comes from contact with the teeth, not ingestion. Others point to fluoride being available in other forms, making community water fluoridation unnecessary and excessive.


Multiple studies have determined that adding low levels of fluoride to drinking water is an effective method for preventing cavities and tooth decay because it strengthens tooth enamel. While low concentrations provide protection, high levels can have an adverse effect. Drinking water concentrations between 0.9 and 1.2 mg/L can cause mild dental fluorosis a dental condition that can vary from barely noticeable white spots on teeth to staining and pitting. Water containing 3 to 6 mg/L of fluoride can result in skeletal fluorosis, impaired brain functions in adults and impraired neurodevelopment in children. 


The maximum allowed levels have changed over the years, as sources of fluoride have become available. When fluoride was first added to water in January 1945, Grand Rapids, Michigan, nearly all fluoride intake came from drinking water or food and beverages prepared with fluoridated water. Since then, products like fluoride toothpaste have been developed, increasing daily fluoride exposure and decreasing our dependency on it in drinking water. When it comes to how much fluoride should be in drinking water, there is a maximum allowed "safe" level and another limit defined as "optimal". The EPA has set 4.0 mg./L of fluoride as the maximum "safe" level, "based on the best available science to prevent potential health problems." The National Research Council is in agreement with this level, having "concluded that the EPA maximum contaminant level of 4 mg/L in drinking water was an appropriate standard and was safe for ingestion at levels considered optimal for oral health." Additionally, the EPA set a secondary standard (SMCL) for fluoride at 2.0 mg./L. Different than safety levels, SMCLs are recommendations to regulate "contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water." Water systems are not required to comply with secondary standards. As for an "optimal" level, the U.S. Public Health Service recommends a fluoride concentration of 0.7 mg/L, a level supported by the U.S. Surgeon General in a 2015 report. The FDA also recommends that bottled water concentrations should not exceed 0.7 mg/L. It's important to note, the maximum amount of fluoride that an adult can safely consume daily is 10 mg/L. Serious health risks can arise from consuming fluoride at such a great quantities.


If you're concerned about the quality of the water in your home, and want to know how much fluoride is in your drinking water, there are a few ways to find out:

  1. Test the water yourself. Using an at-home kit, you can take a water sample and then mail it to a lab for analysis. An important note: Not all test kits are the same. Make sure the kit you purchase will test for fluoride and any other contaminants you are concerned about.
  2. Check your city's levels online. The Centers for Disease Control and Prevention has a searchable database called "My Water's Fluoride" that provides detailed information about the fluoride level in your water system.
  3. Request a water quality report. All public water systems in the U.S. are required to provide customers with an annual Consumer Confidence Report that details the water quality in your community; just ask for a copy.
  4. Call the EPA's Safe Drinking Water Hotline for more information about drinking water safety in your area: 1-800-426-4791.


If you would like to reduce the level of fluoride in your home's drinking water, a reverse osmosis system is uniquely designed for the job. Fluoride cannot be boiled out of water. The reverse osmosis process uses a semipermeable membrane to remove larger particles from your water supply.


While there are a variety of reverse osmosis filtration systems that will reduce fluoride levels, these are highly rated top performers:


Regular replacement of the filter and/or cartridge is critical to maintaining their effectiveness and reducing bacterial contamination. An overused or out-of-date filter can become dangerous because the filter will no longer trap contaminants, allowing them to leach back into your water. For the safety of you and your loved ones, it's important not to put off replacement too long. There are four effective ways of knowing when it's time to replace your water filter:

  1. Follow the manufacturer's recommendations. Their specified replacement timing will err on the side of caution so you can be assured that your water quality will always be safe.
  2. Measure usage. Install a filter measurement meter or filter monitor that connects to the incoming water line that feeds the filter system and measures the number of gallons that pass through. Then using the manufacturer's recommended usage limit, program the monitor to alert you when you've reached the allowed number of gallons. You'll know exactly when it's time to replace the filter.
  3. Read your water bill. If your home is supplied with municipal water, your water bill will tell you exactly how much water is used monthly. Compare your actual usage to the manufacturer's recommendation and plan the replacement accordingly.
  4. Monitor manually. If you have non-municipal water, the most cost effective method is to monitor your filter manually either with your palate or a water testing kit. Start with routine water tests that look for lead, microorganisms and other contaminants to verify whether your filters are still removing them. For drinking water systems, simply fill a glass with water and check the flavor yourself. You'll be able to see or taste when the filter is exhausted and no longer purifying your water because the water flavor will be unpleasant.


For answers to fluoride-related questions, recommendations on the best filter for your home or general drinking water questions, contact us.