>Im thinking disposable CO2 canisters can't be that good for the environment either?

Who's disposing of those things, they are much cheaper to swap out.

They're not disposable. They reuse them. You get a rather sizable discount (50%) for giving an empty one back when you get a new one.

I wonder why they don't market that more widely, I was looking for refills around a display and couldn't find them. There was nothing about where or how to get a canister that I could find on the outer packaging.

The CO2 canisters are refilled/exchanged and not disposable. It certainly passes the smell test to me and they have a ton of info on their carbon footprint on the website. For me, I love the convenience of not having to go buy bottles of soda water and then recycling them after. You just fill the sodastream bottle, carbonate, drink, rinse, repeat.

Not only are the canisters "not disposable", they also are not the property of the purchaser of a SodaStream device. Instead, canisters remain property of SodaStream and are licensed to the purchaser.

http://www.sodastreamusa.com/Assets/ULC.jpg

Even if the canisters were disposed instead of reused, recycling metals is ridiculously efficient.