In recent decades, water consumption has become more important in maintaining good oral health. This is because most U.S. communities now add a mineral called fluoride to their water systems. Fluoride helps strengthen teeth and protects them from decay. In addition, water moistens body tissues, including those of the mouth.

Water is the most abundant and essential nutrient in the human body. It comprises approximately 60 percent of the total body weight of a normal adult and provides the medium by which nutrients reach all body cells and waste products are excreted. It also serves as the medium in which many metabolic reactions can occur.

A person cannot survive for long without drinking water. Low levels of water can lead to dehydration, a condition in which water loss is greater than water intake, resulting in a negative water balance. Although people can survive for several weeks without consuming any food, they cannot live more than a few days without water. Since the human body cannot store water, it must be constantly replenished. Most experts recommended that people drink at least eight 8 ounce glasses of water daily.

In the 1930s, scientists first noticed that people who drank fluoridated water had less tooth decay. Fluoride is a mineral that helps harden developing tooth enamel (remineralization) and protects teeth from tooth decay. Beginning in 1945, some communities began adding fluoridation to drinking water and for more than 50 years, the American Dental Association (ADA) has recommended that others follow suit.

When communities decide to fluoridate the water supply, the amount of fluoride that is naturally found in water is artificially boosted to a level that can protect teeth from decay. Usually, this requires adding just a tiny amount of extra fluoride.

Fluoridation of community water supplies is the most important public health tool for preventing tooth decay, according to the ADA. Regular consumption of fluoridated water helps to prevent the complications of tooth decay such as abscessed teeth, which may require tooth extraction. Dental plaque absorbs some of the fluoride. Fluoride from water also rests loosely on dental enamel and remains in saliva for a period of time (about one to two hours). Certain beverages (e.g., fruit juices) and foods (e.g., spaghetti sauce) may also contain some fluoride if they are processed in areas where the water supply contains the mineral.

Fluoridation of the water supply is estimated to reduce tooth decay by between 20 percent and 40 percent. More than two-thirds of Americans live in communities where the water is fluoridated, according to the ADA. People can find out whether or not their water supply is fluoridated by contacting a local dentist, the local or state department of health, or the local water supplier.