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Health Department - Fluoride in Private Drinking Water Wells

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1. What is fluoride and how does it get into a well water supply?

Fluoride, derived from fluorine, is present in the Earth's crust. When a well is drilled and used, there may be fluoride present in the aquifer, which would then bring fluoride into the household water supply. Not all water supplies have the presence of fluoride.

2. Is fluoride needed for a healthy body?

Fluoride helps prevent tooth decay, but too much of it can be harmful. Too much fluoride in water for children less than eight to nine years old can cause dental fluorosis, which is a discoloration of the permanent teeth. This condition may be unsightly, but can be treated by cosmetic procedures. Significantly higher levels of fluoride use over time can cause bone disease.

Fluoride toxicity can occur in rare instances if fluoride is ingested in large amounts over a short period of time, most commonly due to accidental overdose of fluoride supplements. Fluoride toxicity can cause diarrhea, nausea, abdominal pain, vomiting, increased salivation, or increased thirst. These symptoms start half an hour after ingestion and may last up to 24 hours.

3. How do I know if fluoride is in my well water supply?

View the fluoride testing webpage for information.

4. What are the safe levels of fluoride?

Levels below 2 milligrams per liter are considered safe and beneficial to teeth and bones. A secondary standard for fluoride has been set by the Environmental Protection Agency (EPA) at 2 milligrams per liter to protect consumers against dental fluorosis.

The EPA has set standards for public water supplies for fluoride at 4 milligrams per liter. Some individuals that consume water in excess of 4 milligrams per liter over many years could get bone disease, which can include pain and tenderness of the bones.

5. How can I treat my water for fluoride if it exceeds the maximum contaminant level in my water supply?

Reverse osmosis systems can reduce the amount of fluoride present in a water supply. Systems should be certified by the appropriate approved testing agencies. A fluoride resample should be obtained once the system is in operation to insure that the fluoride level in the water is below the maximum contaminant level. The Loudoun County Health Department recommends water supplies that exceed a fluoride level of 4 milligrams per liter be treated.