After Sonterra MUD, a development in Jarrell, was alerted about higher-than-safe levels of fluoride in their water supply, KVUE wanted to see if their situation was isolated or mimicked in nearby communities.
Sonterra's high fluoride level stems from naturally occurring fluoride sources in their groundwater. The MUD has to then dilute to make drinking water safer.
KVUE's Jason Puckett logged more than 450 Texas Commission on Environmental Quality reports for public water sources in Williamson County and found that in the last year, Sonterra MUD was the only source to cross the recommended 4 mh/L limit.
However, fluoride levels in the mid- to high-threes were found at the Jonah Water SUD, Green Acres Water Supply, Walburg Water System and the Weir Water Works.
GO HERE for a detailed list of TCEQ Williamson County levels.
To determine what those numbers represent and whether residents should be concerned, we spoke with University of Texas Chemistry lecturer Dr. Kate Biberdorf.
"Fluoride is small," she said. "It literally looks like water -- and literally to look at it with a naked eye, you would not be able to say this has Fluorine in it or it doesn't."
Dr. Biberdorf explained that each water system is different. Some, such as Sonterra MUD, have too much naturally occurring fluoride. Others, including Austin's and Round Rock's, have almost none.
While there are state and federal mandates for the maximum level of fluoride a water source can have, in many cities, such as Austin, fluoride is actually added to the water supply.
"It's 100 percent to help our teeth," Dr. Biberdorf said. "The problem is when you have fluoride in the water, anybody who drinks it -- a baby, senior citizen, someone who is sick -- you can't really control how much fluoride that person is in taking."
In high doses, or in younger children whose kidneys aren't as effective at filtering, high concentrations of fluoride can actually do the opposite of the intended effects and can lower bone density and more.
Dr. Biberdorf said she has faith the mandated levels are safe but advised residents to take some of their awareness into their own hands as well.
"If my water company told me I was near that four level, I wouldn't panic," she said. "But at the same time, I would be aware of what's going on, and personally as a chemist I would take my own water and go test it myself."