Water fluoridation depends upon:
Water fluoridation depends on the temperature in that area and body weight.
Galagan formula for ﬂuoride: 
This is usually calculated by the formula given by Galagan and Vermillion in 1957.
Ppm of F ‾= - 0.038 +0.0062 t temperature in Fahrenheit.
‘E’ is the estimated daily water intake for children in ounces per pound of body weight.
‘t’ is the yearly mean of the daily maximum temperature in Fahrenheit.
Essentials of preventive and community dentistry 
Soben Peter 
5th edition
The temperature in that area
Body weight
Both
None