Revised 29 September 2010

What is fluoride?

Fluoride is a mineral that occurs naturally in soil, air and water. The naturally occurring concentration of fluoride in fresh untreated drinking water ranges from 0.01 mg/L to 11.00 mg/L in Canada.

Fluoride helps to prevent tooth decay by re-mineralizing cavities when they first begin to form and increasing the resistance of tooth enamel to acids that cause tooth decay. Research has shown that people of all ages who regularly consume drinking water that has been fluoridated within recommended ranges, have between 15 – 40% fewer cavities.

[ top ]

Does Ottawa’s drinking water contain fluoride?

The City of Ottawa adds fluoride to the drinking water for the central distribution system. The target level of 0.70 mg/L (ppm) of fluoride in the drinking water is maintained in accordance with a recent study entitled “Findings and Recommendations of the fluoride Expert Panel to Health Canada

The target level of 0.70 mg/L is within the 0.50 – 0.80 mg/L concentration range for fluoride suggested by the Ontario Ministry of the Environment, where fluoridation of drinking water is practiced.

The City does not add fluoride to the water from the five communal well systems (Carp, Munster, Richmond, Shadow Ridge and Vars) that are owned and operated by the City. However, drinking water from these systems may contain naturally occurring fluoride in the range of 0.10 mg/L to 0.70 mg/L.

[ top ]

Why does Ottawa add fluoride to drinking water?

Under the direction of the Medical Officer of Health, Ottawa adds fluoride to adjust the natural concentration of the water supply to the level recommended for optimal dental care. fluoride is added to drinking water as a public health measure in accordance with provincial guidelines for drinking water and recommendations supported by the Ontario's Ministry of Health, Health Canada, the World Health Organization and American and Canadian Dental Associations.

[ top ]

Who monitors the level of fluoride in drinking water?

There are two levels of fluoride monitoring in Ottawa. The fluoride level is continuously monitored at both water treatment plants using on-line analyzers. In addition, the fluoride concentration is tested throughout in the water distribution system by certified operators. The results of the monitoring program are reviewed by Ottawa Public Health. The Ontario Ministry of the Environment suggests a concentration range of 0.50 – 0.80 mg/L with a Maximum Acceptable Concentration (MAC) of 1.50 mg/L for fluoride in drinking water. If the level exceeds 1.50 mg/L it must be investigated immediately and reported to the Ontario Ministry of the Environment (MOE) and the Medical Officer of Health.

[ top ]

How is fluoride added to the drinking water?

The City of Ottawa uses Hydrofluorosilicic acid  ( HFS ) to fluoridate drinking water. It comes in the form of a liquid solution that is delivered to the treatment plant in tanker trucks. Liquid HFS is added to drinking water during the final stage of the water treatment process. All chemicals used in water purification must be approved for application in potable water. This means that they must meet a number of product quality standards including AWWA/ASTM and NSF- 60 certification.

[ top ]

What about health concerns of adding fluoride to drinking water?

In September 2009, the City of Ottawa reduced the target level of fluoride in drinking water to 0.70 mg/L in response to the new level recommended by Health Canada. These changes were made under the direction of the Medical Officer of Health.

The possible effects of fluoride in drinking water is one of the most intensely researched areas of public health with several hundred recent publications. A number of recent, major reviews have been commissioned by governments around the world to examine the potential for adverse health effects related to fluoride (Australia, United Kingdom, United States, and Canada). As part of our ongoing review, the Ottawa Public Health Department has reviewed these major studies. All concluded that water fluoridation is a safe and effective method of reducing tooth decay at all stages of life.

Despite claims to the contrary, the studies confirm that there is no credible scientific evidence to suggest adverse health effects related to water fluoridation.

Water fluoridation is endorsed by reputable health organizations throughout the world including the World Health Organization and Canada’s national agency, Health Canada.

[ top ]

What happens when the supply is interrupted?

The City of Ottawa maintains a concentration of 0.70 mg/L (ppm) of fluoride in the drinking water provided to the central distribution system. Occasionally we stop adding fluoride for short periods during equipment maintenance and inform the Medical Officer of Health and the Ontario Ministry of the Environment of the interruption. When the interruption is finished we resume adding fluoride at the same level. We do not lower or raise the concentration to make up for interruptions in supply.

[ top ]