Earlier this month, around the time of the Super Bowl, a minor controversy erupted around SodaStream, the make-your-own-soda company. SodaStream sells countertop soda makers powered by small tanks of compressed air. The cheapest machine costs around eighty dollars. You fill a small bottle with tap water and attach it to your SodaStream; when you push a button, air is injected into the bottle, creating sparkling water. Afterward, by adding flavored syrups, you can make your own soda at home. The company sells dozens of different 'SodaMixes,' with pleasingly generic names like Diet Cola, Dr. Pete, and Energy, but you can also make your own syrups. The instructions caution you not to carbonate anything other than water (like, say, margaritas). The Internet, though, overflows with blog posts written by people who have �gone rogue� with their SodaStreams and, for example, carbonated white wine to make 'champagne.'

In areas that have good tap water this system makes a lot of sense. First of all, because hauling home soft drinks is a huge pain - it's heavy and bulky to haul that much water (with flavorings) around manually.

It's also cheaper - by a rather large margin, if you shop around for the syrups. That depends on where in the world you are, I'm sure, but making sparkling water will leave you with a liter cost that can be counted in cents worth of carbon dioxide rather than dollars/euros for a bottle of "mineral water" that isn't all that special.

I don't think the big soft drink pushers have that much to worry about, brand recognition is still a factor and they spend enormous amounts of on-going ads to keep it that way, but for savvier consumers stuff like the sodastream makes a lot of sense.