If you have some spare time I believe it is worth reading an interesting publication produced the ADA (American Dental Association).
For example this is a table that is on page 25 suggests that infants should get very close to 0 ZERO fluoride.
The following is a quote for page 26. In my opinion suggests that children get a lot fluoride through drinking tap water.
Children living in a community with water fluoridation get a portion of their daily fluoride intake from fluoridated water and a portion from dietary sources which would include food and other beverages.
When considering water fluoridation, an individual must consume one liter of water fluoridated at 1 part per million (1 ppm) to receive 1 milligram (1 mg) of fluoride.
Children under six years of age, on average, consume less than one-half liter of drinking water a day.
Therefore, children under six years of age would consume, on average, less than 0.5 mg of fluoride a day from drinking optimally fluoridated water (at 1 ppm)
That is not even taking into account another statement that studies show children who brush their teeth twice daily are swallowing on average “0.6mg of fluoride” as well. You can reduce this unnecessary expose to fluoride by using a reverse osmosis system.