No evidence has been presented that indicates carbonation in carbonated water is bad for people. Consumption of carbonated colas has been linked to low bone mineral density, and the sugar content in carbonated sodas plays a role in tooth decay.
Some studies have indicated that carbonated water aids digestion and relieves indigestion and constipation. Concerns that carbonated water leaches calcium from teeth, causes kidney stones or damages tooth enamel are unsubstantiated by clinical studies. While carbonated water is a bit more acidic than water, there is no evidence that unflavored carbonated water damages tooth enamel. The only drawback to drinking carbonated water is that it can cause people to burp and pass gas, especially if it is consumed too quickly.