The US (health based) MCL is ...
Published by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health
The US (health based) MCL is 4 mg/L and the secondary (aesthetics) SMCL is 2 mg/L. The recommended value for fluoride addition is 0.7 mg/L. The WHO recommended GV is 1.5 mg/L. Water consumption patterns affect the dental effects so climate in the area is a factor. It is usual in high fluoride small communities to give bottled water to children while their teeth are in the formative stage. Activated alumina works well for water treatment. Anion exchange resins also work but they can be sources of nitrosamines.