SodaStream Air Cartidge

SodaStream products are readily available in my local Carrefour. Perhaps it's worth asking at your local branch.

If you can understand a bit of French, it's dead easy. You can do it online or go to a shop that sells Sodastream stuff.

http://fr.sodastream.be/faqs/#cylindre-de-co2

Having said that, we got rid of ours as we only used it for fizzy water and it made the bubbles too big!

Both Mediamarkt and Van Den Borre, for example...