We drink a lot of carbonated water in my household. Enough, in fact, that we've owned a trusty SodaStream Fountain Jet (the company's entry-level carbonator) for years. Even with the sunk costs of the machine itself and the purchase of a pair of tanks, we know it paid for itself long ago.

The per-bottle cost is roughly 25 cents per liter of carbonated water. It's much cheaper than supermarket seltzer, and it involves less worry about the environmental costs of making plastic and glass bottles and shipping them around the world. I like that.

When I refill my two new tanks, it costs $10 instead of $45, and I've got some nice, cheap fizz on tap.

The thing I don't like is that the small SodaStream tank refills cost about $15, each one making roughly 60 liters of carbonated water. Technically, you're really paying for 410 grams of CO2, part of the very air you've been breathing for free all of your life. Fifteen bucks (or $30 for a bottle a whisker over twice that size) is the expensive convenience price you pay to be part of SodaStream's proprietary system. It's at the heart of the company's profit model. Get in the habit of exchanging spent tanks for new ones every few months (in my case it's $45 for a small and a large tank) and you'll eventually become annoyed about paying a premium for one of the most common gases out there.

After a few years of this, combined with trips to places like Bed, Bath & Beyond to exchange the canisters, I got fed up.

During that time, I wrote about different carbonators and carbonated drinks which brought me to some of the less-traveled corners of the Internet. One item that kept popping up was an adapter you can stick on a paintball canister, allowing you to plug the whole thing into a SodaStream machine. Dubbed the SodaMod, it was a fairly-prohibitive $60, but I recently noticed that it had competition at less than half the price. A bit more research revealed that refills of the paintball canister, which is larger than a 60-liter SodaStream canister, can be done in a sporting goods store for $5. Some cocktail-napkin math revealed that the price per liter with this setup is about a quarter of the price of the all-SodaStream option. I became interested in a hurry.

Josh Valcarcel/WIRED

Fizzy Logic

I set some parameters for how I wanted this to work, notably including that I wanted it all to fit inside the existing SodaStream (or, perhaps better, the DrinkMate, which uses SodaStream canisters) housing—no tubing spiraling out of the back, no nearby external tank. I wanted definite savings. I wanted it to be as easy as exchanging the SodaStream canisters and call on nothing more than what a friend calls "Ikea skills" to put it together. I did not want to build my own carbonation rig.

I was willing to root around to figure out how it all works and which parts to buy, surprisingly time-consuming knowledge which I've laid out at the bottom of this story, clear as a bell, for you, dear reader. As long as you've got those Ikea skills, have the time to call around your neighborhood to figure out who will refill the tanks, and regularly drink soda water, this is the money-saving way to fly.

You'll need to do two things to get set up: order the hardware, and call around to figure out where to get the tanks refilled.

The only snafu I ran into was finding a place near me to refill the tanks. The closest sporting goods shop (the first and easiest place you should try) was a 20-minute drive away. A paintball shop was half an hour away. Get clever, however, and you'll eventually find something—a welding shop, a dive shop, a home-brew store, a nice guy at the local Airgas who knows where you should go. (Depending on where you live, picking up a $10 adapter that puts a standard CO2 tank attachment on a paintball bottle might give you more options.)

For the tanks, buy SodaMod's. They're made to be used with a carbonator, so they've been scoured clean. I'd considered buying Amazon's top-selling "regular" tank, then taking it apart and scrubbing it out with a toothbrush, but the SodaMod tanks are only a few dollars more. Buy two or three and you'll be set for months at a time.

As for the adapters that connect the tanks to the SodaStream/DrinkMate, you can find several options with a quick online search. The brass SodaMod ($60) and Interstate Pneumatics ($18) appear to be exactly the same thing with different branding. They both have a tiny adjustable set screw which might need some quick tweaking (see the 1:30 mark) to get the air flowing. In my testing, the Interstate Pneumatics needed no adjustment, and the SodaMod needed a minute of (easy) fussing with it to get it going. For $25, the stainless-steel Trinity adapter is adjustable, but it arrived ready to roll. The Trinity's also half-an-inch taller which makes getting the tank in and out of the SodaStream/DrinkMate a bit easier. In short, all three adapters work just fine.

In this era of knockoffs, it's worth raising a bit of a caveat here. Try to ensure that you get an adapter with lead-free brass or stainless. SodaMod, which claims a patent on its design, says its adapter costs more because it is lead-free. A tech at Interstate Pneumatics says its adapter is "food grade."

My SodaStream tanks are now banished to the back of my cupboard and when I refill my two new tanks, it costs $10 instead of $45, and I've got some nice, cheap fizz on tap.

Your Shopping List

Buy an adapter.

There are many. I had great results with the SodaMod, Trinity, and Interstate Pneumatic models.

__Buy Two or Three __SodaMod tanks

Get the largest tank that will fit inside your carbonator. The 24-ounce tank will fit inside the Fountain Jet, Revolution, Dynamo, Fizz, Splash Play. The 12-ounce tank will fit inside the Penguin, Genesis, Crystal, Source, Source Metal, Power. The 9-ounce tank fits inside the Pure.

The 12-ounce tank also fits inside the DrinkMate, an excellent alternative carbonator I reviewed earlier this month.

Food writer Joe Ray (@joe_diner) is a Lowell Thomas Travel Journalist of The Year, a restaurant critic, and author of "Sea and Smoke" with chef Blaine Wetzel.