Carbonated water: water containing dissolved carbon dioxide, producing bubbles. Often refers to plain sparkling water (unsweetened) but can also mean soda water.
暑い日は冷たい炭酸水を飲むとすっきりする。
On hot days, drinking cold carbonated water feels refreshing.
このレシピでは炭酸水を使って生地をふんわりさせる。
This recipe uses carbonated water to make the batter fluffy.
スーパーで無糖の炭酸水を箱買いした。
I bought a case of unsweetened carbonated water at the supermarket.