We traveled to Topeka, which treats 30 million gallons of water a day. The capital has fluoridated its water for decades.
"Is there a lot of controversy around it here in Topeka?" said Bruce Northrop who runs the Topeka Water Plant. "In the 40 years I've been doing it, there has been very little controversy about adding fluoride to the drinking water."
Topeka dentist Dr. Amy Thompson says the same thing. In her practice, most of her patients don't even know about it - or they simply don't talk about it.
"It's not something you hear about around here." Dr. Thompson told us. "Here in Topeka it's not something you hear a lot about."
We were able to take a rare look inside the Topeka water plant. The concentrated fluoride is delivered by truck and stored inside 4,000 gallon tanks. Those tanks last around 3 months.
The system is controlled through computerized calibration pumps which deliver .7 parts per million of fluoride to the water during its final stages of filtration. After that, it's pumped out to homes and businesses throughout the area.
Northrop says the concentrated material is a lot different by the time it's added to the water. You may have seen the warning on the tanks and in anti-fluoride campaigns.
Northrop says, yes, in the concentrated form - fluoride is dangerous. Northrop points out that that is also the case for chlorine and other chemicals used to treat drinking water.
"As far as a work hazard, the fluoride is minor compared to the chlorine we deal with on a daily basis," Northrop said.
Once those chemicals are diluted, a large majority of doctors, dentists and health professionals say it is safe.