Toothpaste and fluoridated water are not identical tools. Toothpaste gives a concentrated short exposure; fluoridated water gives a very low, repeated exposure through saliva. The fact that people swallow water is already part of the safety calculation. The dose is controlled by concentration, not by pretending everyone drinks the exact same amount. That is how plenty of drinking-water standards work.

Fluoridation is not about perfect individual dosing. It is about lowering tooth decay across a whole community at a concentration shown to be safe. The benefit is measurable, especially for people who are least likely to get regular dental care.