Stir in the carbonated water at the last moment, just before cooking the pancakes.
Pour a ladle of the batter into the pan and gently tip and twist the pan so that the batter covers the entire bottom of the pan. When the top of the batter bubbles, turn the pancake over and cook for 4 or 5 seconds longer. Remove the pancake. Continue until the batter is all cooked; add butter before cooking each pancake.
Note: These pancakes can be served hot or cold.