Is sparkling water bad for you?: Dr Ros O' Leary, Periodontist
Any acid in the mouth has the potential to cause erosion, so wear on your teeth. And erosion is an accumulative thing – so even if you only have small amounts, if you add that up in to days, weeks, months, then years - then the amount of wear on your teeth can be significant.
However we need to be careful, because it is a mild acid, and when people talk about carbonated drinks, when we talk about say like colas and fruits, and even flavoured waters, that have had citric acid added to it, those have PHs of about two to three – so those are strongly acidic.
Therefore in the scheme of things, it's best if you don't have carbonated water all the time, maybe retain it to meals. Definitely if you use a straw, because the less time that any of these things are in the mouth, the better it is for you. But I wouldn't say you can never have carbonated water.