Where can I find information on Fluoride in Water?

Fluoride and Groundwater

FLUORIDE IS GENERALLY PRESENT in low concentrations in groundwater on Prince Edward Island . Fluoride is usually derived from fluorite (the main fluoride mineral of igneous rocks) and the minerals apatite and mica. The concentrations of fluoride can vary with the source of water and locale. Natural levels in Canadian water supplies have been reported from less than 0.1 mg/L to 4.5 mg/L. Detectable fluoride concentrations are occasionally found in specific situations on Prince Edward Island , where because of the age of the water and the period of exposure to chemical leaching processes, fluoride concentrations may be elevated. This most often occurs in deeper wells or other areas where groundwater has been in contact with geological formations for a long time. These waters are often characterized by their "naturally softened" character. Some coastal areas of Queens and Prince counties do experience naturally softened groundwater.

Guidelines
Minute quantities of fluoride in drinking water have proven beneficial in preventing tooth decay. Excessive fluoride causes mottling of tooth enamel; furthermore, teeth may become brittle because fluoride affects tooth density. These defects are more evident where children drink too much fluoridated water while their permanent teeth are still forming.

Criteria for drinking water have been formulated for the most sensitive water consumers - children - and are related to the quantity consumed. The Guidelines for Canadian Drinking Water Quality 1989, has set the maximum acceptable concentration for fluoride in drinking water at 1.5 mg/L. That level is presently under review and may be lowered to 1.0 mg/L which is considered the optimum level for the control of dental cavities.

Treatment
Practical, effective water treatment processes for fluoride removal are specialized. In municipal water systems, the treatment requires very high alum applications to obtain significant fluoride removal. Lime softening of high magnesium waters can be effective, but high dosages are required. The optimum solution for removal of fluoride in private drinking water supplies is reverse osmosis treatment. Fluoride data from reverse osmosis operating plants suggest removals to less than 1.0 mg/L down from 2.2 mg/L. However, reverse osmosis systems available for home use make a limited amount of water for drinking or cooking - only a few gallons a day at the most.

The application of the above-mentioned treatment processes will depend on site specific and economic factors. An alternative to treatment is sometimes well reconstruction or replacement.