Some people want fluoride from water systems. Here's what it does.

MINNEAPOLIS — Brushing your teeth when you start and end the day keeps them healthy. In between those times, drinking a glass of tap water, especially in Minnesota, can do the same. Fluoride is a mineral naturally found in fresh and salt water, but in much of the U.

S., a tiny amount more is added at water treatment plants to help prevent tooth decay. Every day, bacteria in our mouths create acid which removes minerals from a tooth's enamel.

Fluoride replaces those minerals, making teeth more resistant to the acid and, in turn, decay. The CDC considers it one of the 10 great public health interventions of the 20th century, leading to a dramatic decline in cavities after 1945 when community fluoridation started. Minnesota has a law mandating that community water systems be treated with fluoride.

As of 2022, the CDC reports there are 4,491,474 people in the state served by a community water system. Of that number, 98.9% are receiving fluoridated water.

In Wisconsin, where each municipality decides whether to add fluoride, that number is 84%. It's significantly lower in other states like Utah (43%), Montana (32.8%) and New Jersey (16.

2%). Across the entire country, 63% of the total population receives fluoridated water. "The Department of Health says that we have to add at least 0.

5 parts per million (ppm) and not more than 0.9 ppm, so we target 0.7 ppm," Justine Roe, water quality supervisor at St.

Paul Regional Water Services, said. That target, 0.7 ppm, is the equivalent of .