AFS Statement on Sandy, Utah

March 19, 2019

The fluoride overfeed in Sandy City, Utah, has been in the media for the past few weeks. The overfeed continues to be an ongoing investigation with information coming out as more is learned. There are many questions being asked about this overfeed, and the American Fluoridation Society wanted to update you on what is known at this time.

1. Here is what we do know from several media, city, and health department resources:

    • Those impacted by the fluoride overfeed were residents of 50 homes

    • The fluoride levels were returned to normal within 2 hours by flushing the pipes,

      which was done by the city’s public utility department crews

    • County health officials have said there should be no long-term health effects from the fluoride overfeed

    Additional testing:

    • The city has tested nearly 3,000 homes for lead and copper levels.

    • “On Sunday, February 17, the No Drink Order was lifted for all affected zones.”

2. How did this all come about? 


The fluoridation equipment was undergoing maintenance by a contractor. Normally, the fluoridation system would be shut off during this maintenance. The maintenance might take a month, but it would have no impact on cavities for the developing permanent teeth of children (once they come in) since the flow of fluoride is interrupted for such a short time. Their permanent teeth develop slowly under the gums and this short of an interruption wouldn’t have an effect on them.

Human error:

The fluoride pump controls are normally interconnected with the controls for the water pump(s). If there is interruption in electrical service, the fluoridation system would automatically shut down and stay off.  

A snow storm occurred that caused a power failure at the water plant. The water and fluoride pumps lost power and were not running.

In this case, the fluoride pump was inappropriately hardwired in non-compliance with state regulations. What “hardwired” means is that the power source for the fluoride pump was powered independently of the water supply pump. When the power resumed, the fluoride pump restarted and continued to pump fluoride into the water supply even though the water supply pumps did not restart.

Frequently Asked Questions:

A Q&A Update interactive document from the Sandy City Utilities is available here. 

Going forward from here:

“A brief exposure to high levels of fluoride should not cause long-term adverse health effects…” Sandy City and the state of Utah are continuing to investigate the events that led to this overfeed. We do not yet know everything that happened. If you would like more information, please contact the Utah Division of Drinking Water.