Well, it's been done. It's not a good idea, but it's been done!
The reason is that soda is much more highly carbonated than soda. Also, it's important to stick the soda in the fridge as soon as it's carbed up so the bottles don't explode since the yeast doesn't stop like it does with beer. Plastic soda bottles are the best choice for carbonating soda.
Broken Leg Brewery
Giving beer a leg to stand on since 2006