SodaStream would have you believe that you’re saving a bundle of cash each time you use one of their do-it-yourself carbonation machines to make a soda. But how economical is it really? How much soda do you need to drink before you actually break even and begin to recoup the cost of the machine? Business Insider’s Sara Silverstein did some quick math to find the answer, and the results aren’t what you’d expect.

Her methods are fairly simple to follow. She starts with a mid-level SodaStream machine that costs $130, and comes with one free CO2 cartridge that would otherwise cost $15. Of note: Silverstein subtracts this “free” $15 from the initial overall cost, which I contend is a mistake, since it’s a sunk cost and should be included regardless of its presumed value. This makes my calculations slightly different than hers.

There’s a lot of number crunching going on here, so if you’d rather skip the mathematical details, the good stuff is in bold.

### Sparkling Water

So, **how much sparkling water would you need to drink before you recoup the $130?** First, you need to figure out the cost per liter of a drink made with SodaStream, and compare it to the cost per liter of a bottle of carbonated water.

When used as directed, one cartridge ($15) makes 60 liters of plain carbonated water. Therefore, **sparkling water costs roughly $0.25 per liter when you make it with SodaStream** ($15/60L=$0.25 per liter). Comparatively, Silverstein found that one liter of bottled sparkling water costs $0.79, so you save about $0.54 per liter when you use SodaStream ($0.79-$0.25=$0.54).

Using that number, **you’d have to drink somewhere around 240 liters of sparkling water in order to break even and start saving money** ($130/$0.54 per liter=240.7 liters). That’s roughly 22 fluid ounces of soda every day for one year.

### Flavored Soda

Because flavored soda requires the addition of SodaStream’s Sodamix flavor syrup, you save far less per liter than you do with plain ol’ sparkling water, and therefore need to drink more before you recoup the cost of the machine.

Each one of the $5 Sodamix bottles makes 12 liters of flavored soda. So in order to make 60 liters, you’d need 5 of them, which would cost $25 dollars. Add that to the cost of one CO2 cartridge ($15), and you need to spend $40 to make 60 liters. Divide those, and **the cost per liter of flavored SodaStream drinks comes out to roughly 0.67 cents per liter.**

Comparatively, Silverstein found that the average liter of bottled generic cola costs about $0.89, so **you only save about $0.22 per liter when you make flavored drinks with SodaStream **($0.89-$0.67=$0.22).

So since you only save less than a quarter each time, **you’d need to drink about 591 liters of SodaStream cola before you break even and start saving money** ($130/$0.22 per liter=590.9 liters).** **To put that in perspective, that’s 1.62 liters per day (about 4.5 cans) every day for an entire year.

### Summary

So in a nutshell, **you’ve got to be a serious soda drinker in order to make SodaStream an economical purchase**. We’re talking regular daily intake of a relatively high volume. If you only drink soda occasionally (once or twice a week), it’ll take you years, or potentially even a decade to recoup the cost of the SodaStream machine.

However, the ball game may be completely different if you’re part of a family of soda-lovers with two kids or so. In that situation, the savings could come fast, especially if aunts, uncles, nieces and nephews are popping by often.

That being said, we recognize that this analysis is purely economical. Part of the appeal of SodaStream machines is that they help to reduce waste created by plastic bottles, so if you’re in it for the environmental benefits more than the financial savings, by all means, get your fizz on.