Fluoride is a mineral that occurs naturally in soil, water and air. It helps prevent tooth decay by making the outer layer of teeth more resistant to acid attacks from bacteria.

The fluoride level in drinking water may be adjusted to control dental decay. The optimum concentration is 1.0 mg/L (1 ppm). However, fluoride levels that are too high can result in staining and dental fluorosis, a condition that causes unsightly tooth discoloration.

To determine the fluoride concentration of your drinking water:

Get a sample of your water from your point-of-use (i.e., faucet). Take at least 20 mL (approximately 4 U.S. ounces) for testing to ensure accuracy. Do not use distilled or deionized water for this test because these types of water do not contain any minerals that affect the accuracy of the test results.

Bring the sample to room temperature before testing it using an electronic hardness tester or an electronic conductivity meter with an electrode set specifically designed for hardness testing (see Resources below). If you do not have access to either instrument, contact your local health department or laboratory for assistance with obtaining a reading on your hard water level; they may charge you a fee for performing.

Last modified: October 29, 2022