Note: This is NOT paid content for SodaStream... or Spindrift... or Sparkling Ice...
Now I'm going to illustrate why you should purchase none of these things, and get a SodaStream instead.
At the request of avid sparking water drinkers, I've been tasked with comparing the variable per unit cost of a drink from a SodaStream machine, vs purchasing canned sparkling water in bulk. So I tracked every one of my uses of a brand new SodaStream CO2 canister, until it went flat.
I tracked the number of drinks made, not the number of drinks actually consumed; just like if a can is opened and not finished, that can is still used.
Over 4 months, I got 63 uses out of 1 CO2 canister, which yielded 162 drinks. I can buy each replacement canister for $15 each. Since we're only considering the marginal variable cost, I'm treating the initial SodaStream cost as a fixed sunk cost.
If you want any flavor, we also have to consider something like Bubly drops (~3 bottles of drops would last an entire CO2 canister, which adds $15.33). Or, super bourgeoise, a fresh lime for each use - with a median of 3 drinks per SodaStream use, that's 54 limes at $0.50 each = +$27.
All fall to the SodaStream! Even when using fresh produce each time: