SodaStream

Elly just loves club soda, seltzer water, sparkling water or any water with bubbles.  We used to buy it by the case and then had to deal with the returns.  SodaStream came out with this home carbonated beverage machine but it cost $99.  We decided to pass on getting one until we found one at a yard sale for only $40.  t also came with two water bottles, a 33 oz full CO2 tank and a full smaller 14.5 oz tank.  If I bought it all on the SodaStream web site it would have cost $144.93.

Our SodaStream Machine

SodaStream Canisters

But here's the gotcha with the whole Soda Stream thing. The threads on the Soda Stream tank are proprietary which means they cannot be refilled at a place that sells CO2. (i.e. welding supply stores, paintball stores, beer brewing stores, etc).  The valve on the SodaStream table also has an "anti-refill" valve on it just in case you could figure out how to adapt normal CO2 tank to fill the SodaStream tank.  Soooo! you have to go to a store like Bed Bath & Beyond to exchange the empty tank for a full one.  That costs $15 for the small tank and $30 for the large tanks.  Some stores also don't carry the large refill tank.

SodaStream Threads

After doing a little bit of internet research, I found that you are paying $15 for $4 worth of CO2.  There is  a whole sub-culture of people finding ways to refill their SodaStream CO2 tanks rather than paying the $15.  Most ways include defeating the anti-refill valve by using a dremel tool to carve slots to let the CO2 in and buying an adapter that lets you refill the tanks at welding supply or paintball stores.  This setup costs over $120 and seemed a little complicated to me.

I chose the easier alternative, adapt a paintball tank to the SodaStream.  I bought a paintball tank and adapter on the Internet for $95 including shipping & tax.  The tank is a 20 oz tank and with the adapter fits right in the SodaStream machine. Plus it costs only $4 to have the 20 oz tank refilled at the paintball store!

Paintball Tank

Paintball Tank Threads

Paintball tank with adapter

Now for the math.   First I got the machine, two bottles and two tanks for $40, it was a great deal anyway. You could probably get the same machine with the small tank for around the same price on eBay now.
The total cost of this conversion setup was $99.00.  Since I can refill the tanks for $4 for 20 oz instead of $15 for 14.5 oz; the cost per ounce of CO2 is 83 cents less this way than using the SodaStream tanks.

SodaStream with paintball tank

At that cost difference, it will take me 6 refills to recoup the investment in the conversion equipment (6 refills x .83 cents x 20 ounces = $99.60).  If you add in the cost of the machine itself, it will take me about 9 refills to pay for the entire setup.  Then I get seltzer water for almost nothing!

Plus we buy Blueberry and Raspberry syrup at the local fruit stand and make Blueberry or Raspberry soda for $5.29 for 33.8 fluid ounces of syrup.  SodaStream sell their flavoring syrup for $6.99 for only 25.4 fluid ounces, plus I don't think they even have Blueberry or Raspberry flavoring.