Things You'll Need
Ice cube tray (or a cup with no lid)
Carbonated water or soda pop
Water expands by about nine percent when it freezes. Carbonated water expands at the same rate. The carbonated bubbles cause unusual swelling patterns, but have little impact on the total expansion rate. Sealed, pressurized containers do not allow for carbonated water's expansion. That is why an aluminum soda can will explode and leak frozen soda all over the freezer. Freezing carbonated water in a container that is not completely full, with an open top, will allow the room it needs to expand without making a mess.
Measure the height of the ice cube tray or cup that will will you to freeze the carbonated water.
Subtract 10 percent from the height to find out how full the ice cube tray needs to be. Multiply the measurement by 0.10 and subtract. If, for example, the ice cube tray is one-inch tall, you will be looking for a total of 9/10 of an inch for your full line. You do not need to mark it, just remember where it is and avoid filling the tray all of the way to the top.
Freeze the carbonated water until it forms solid cubes. Expect it to take at least one hour.