We (my GF and I), during warmer weather, used to go through perhaps 1.5 litres of sparkling water a day, in the form of 500ml bottles bought as a 6-pack. Buying sparkling water in bulk doesn't work; big bottles lose fizz every time you open them, especially since you can't help agitating them putting them in and out of the fridge. With small bottles, you only open them once or twice.

6-packs of sparkling water bottles make our SodaStream look much cheaper than the analysis in the article. The SodaStream device itself was reasonably cheap too, I don't remember how much, but no more than 40 GBP. Overpriced for the simple mechanism it is, but kept our hands clean.

We do not generally use the SodaStream flavours. They're almost all horrible. The cola tastes like cola-flavoured penny sweets, and of course to achieve the concentrations required they need to use artificial sweeteners even for non-diet versions. They're all too sweet. The one product they sell that's any good - MyWater, and specifically the lemon-lime essence bottle in the three-pack - has been out of stock for the past 6 months in the UK.

We use the sparkling water for the things that we used to use store-bought for - watering down fruit juices, which are almost invariably 10% sugar in the UK from grape or apple juice filler, and for use with other commercially bought fruit and fruit squash concentrates.