A search of reviews and comments on the consumption and cost of CO2 yields the following results:
- 70 cents or one charger per liter (Amazon Review)
- 20 cents per liter (see lotusmoss' blog comment)
- 50 cents per liter (see mbknight's blog comment)
The instructions for this popular iSi soda siphon seem consistent with an entire charger being required per liter of water, which works out to $0.90 per liter assuming you buy the recommended brand-name chargers.
So, the cost claimed seems to range from $0.20 to $0.90 per liter. Since store-bought carbonated water typically costs somewhere in between, it's not obvious whether this device makes economical sense. (I'm sure there are other advantages, but that's a different topic.)
My questions are as follows:
Does a charger like this really only yield 1 liter of carbonated water?
Is there a way use a single charger to yield more than 1 liter?
Is there an alternative to the iSi-style soda siphon that uses some other source of compressed CO2 that might be more economical?
Has anyone reproduced the $0.20 per liter figure claimed by lotusmoss? If so, how was it acheived?