Fluoride will be reintroduced in Calgary's drinking water starting June 30, about 3½ years after Calgarians voted in favour of fluoridation in the October 2021 municipal election.

The fluoridation process will supplement the natural fluoride in the Bow and Elbow Rivers, bringing it to "the optimal level of 0.7 milligrams per litre," the city said in a release.

That's the fluoride level recommended by Health Canada's guidance for community water fluoridation. Health Canada is one of over 90 nation…