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In order to improve the safety and health benefits of water in your community, your water utility may add chemicals to the water supply. Chemical water treatments, such as chlorination, are commonly used to remove bacteria, mold, algae, unpleasant odors and tastes. Other chemicals, such as fluoride, may be added because of their proven benefits for dental health.

It is common for water utility customers to have questions or concerns about the chemicals added to their water supply. If you or other community members are concerned or unsure why chemicals are being added to your water, consider utilizing the materials in the boxes below to answer common questions about chemical water treatment. The customer service representative or manager at your local utility may also be able to answer questions about specific chemical treatments that are used in your system. ​

ChlorineFluorideEngaging the Community
Sources of drinking water can be contaminated and must be treated with chemicals to remove waterborne diseases and other harmful substances. Adding chlorine to the water supply is the safest and most common form of water treatment in the United States. It is a relatively cost-effective disinfection method, and the treatment continues to be effective while water is distributed to customers.

Studies show that using or drinking water with small amounts of chlorine does not cause harmful health effects and protects against waterborne diseases such as giardia and cholera. Your local water utility regularly monitors your water supply to make sure that chlorine levels are safe for public consumption. You can read more about how your water utility is managing water disinfection, as well as their compliance with disinfection rules, by obtaining a copy of their Consumer Confidence Report.

Adding chlorine to water may change its taste or smell, and you may find that you prefer chlorinated water to untreated water. However, if the taste or smell of chlorine is unpleasant to you, letting your water sit in the refrigerator overnight in an open container will allow some forms of the chlorine to evaporate and remove the offending taste and odor. Boiling your water for 20 minutes or running your water through a filter can also remove most of the added chlorine.

See the Water Chlorination Fact Sheet for a quick summary of the benefits and common concerns regarding water chlorination. For a more in-depth explanation of water chlorination, check out the Chlorine Chemistry Council’s Drinking Water Chlorination: A Review of Disinfection Practices and Issues.

Fluoride is a naturally-occurring mineral found in the soil and water. Fluoride has been shown to prevent tooth decay by strengthening the surface of teeth, which can be eaten away when sugary foods are ingested. In addition to helping prevent cavities, to a certain extent, fluoride can rebuild the surface of teeth with early decay. All water naturally contains fluoride, although rarely enough to prevent tooth decay. For this reason, it is common for water utilities to supplement the water supply with additional fluoride.

Very few adverse health effects have been linked to community water fluoridation. Fluoride levels in community water supplies are closely monitored by water utilities and fluoridation is completely safe at regulatory levels. A minor condition called fluorosis, which causes faint white marks on the teeth, is the most common side effect of overexposure to fluoride. It is harmless and primarily caused by using too much toothpaste, not by drinking fluoridated water. Fluoridation has also been shown to save money in communities by decreasing the rate of cavity treatments, as well as reducing the number of work or school days missed due to dental complaints.

If you or another community member has additional questions or concerns about fluoridation, check out I Like My Teeth’s “Common Questions About Community Water Fluoridation.”

For more information on water fluoridation, visit ilikemyteeth.org. ​

In the Engaging Others on Local Water section, you’ll find resources for a variety of activities and approaches to outreach that will help you to engage the community on a relevant water issues. Many of the activities in the section can be helpful with talking to your community about their concerns of chemicals in the treated water.