In Indianapolis we have 4ppm added to our drinking water.
This means 4 ounces of fluoride exist per 1,000,000 ounces of water
12 ounces of water contains .000012 ounces of fluoride
.000012 ounces of fluoride is .00034 grams (1 oz = 28.34 grams)
.00034 grams is .34 mg (rounded) of fluoride per glass of water
In my toothpaste I have .243% fluoride, it is recommended to use 1 gram per brush. (http://www.colgate.co.in/app/OralHealthMonth/IN/EN/CDC/Steps...)
In 1 gram of toothpaste, there are .00243 grams of fluoride at that %, or 2.43mg fluoride per brush.
I would have to drink around 7.1 glasses of water to equate to just straight up eating my toothpaste out of the bottle. For kids (.25 gram per brush) that would be 1.8 glasses (at 12oz per glass).
Is this correct? Either way, I have hit my tipping point, I bought a RO system today. My kids use fluoride free, as will I from now on...