This was an email I wrote to a friend after mentioning that I had bought a Sodastream:

In addition to the Sodastream machine itself (which I paid ~$100 at Target), here’s what I bought:

  1. Cable (~$30) I bought this version because it didn’t have requirement of closing the tank between uses (unlike some of the ones you find on amazon): ~CO2 Sodastream cable~
  2. Dedicated Cylinder Wrench, nice to have (~$10)
  3. Then I went to AirGas (welding supply) and bought a full 20LB Food Grade CO2 cylinder for $250, I bought their cylinder because there’s no guarantee of them refilling it if you don’t buy it from them (though you can find cheaper empty cylinders on ebay/etc).

So my initial infrastructure cost is ~$400.

Here’s what it looks like:

Sodastream Setup

A refill of the 20LB CO2 Cylinder is $44 dollars. A sodastream cartridge is .9LBs of CO2 and costs $14-$28 depending on where you buy it and if you’re trading in an old cartridge. I was going through ~2LB of CO2 a month which replaced 4 cases/month of Pellegrino ($15-$20/case).

So monthly ongoing cost is going from $70-90 (Pellegrino) to $30-60 (Sodastream) to ~$5 (AirGas). So, assuming no mechanical failures, I should make up my investment well before the time I need to refill the co2 cylinder.

Update 1/15/2021:

My first CO2 canister lasted 4 months, and the second lasted 10 months, which makes me think the first one wasn’t full when I bought it (or, more likely) I accidentally discharged a bunch of gas when I was trying to connect it for the first time).

In any case, I made up my investment and more. I’m very happy with this set up.

Update 8/28/2021:

Third CO2 canister is about to run out, so my usage pattern appears to be 50 lbs CO2 every ~8.5 months. Now the CO2 refills at AirGas have increased in cost to ~$70 (up from $44 pre-COVID), but still doing much better than my original Pellegrino budget.