You may want to add sparkling water to your diet.
Good news: Sparkling water (including the flavored kind), is just as hydrating as non-carbonated water.
Sparkling water contains carbon dioxide, either naturally or added, which provides the carbonation. It also provides a bit of texture, so it may be easier to drink more of it. However, if you're about to work out, still may be the way to go. Sparkling can cause bloating and irritation.
Other factors of carbonated drinks, aside from carbonation, can affect hydration. For example, waters with sugar, other nutrients or electrolytes are more hydrating than plain still or sparkling water. Those take longer to go through the system, so the water stays in the body longer.
So athletes who sweat a lot might be better off drinking lightly sweetened beverages or drinks with electrolytes -- but not necessarily carbonated beverages.