How To: Cheap Homemade Seltzer with a Modified Sodastream
Oh seltzer! Tasty bubble water of the gods. Once you’ve tickled your tongue with this crisp and refreshing remake of boring old water, you’ll never go back.
Our march towards a franken-seltzer machine started innocently enough.
In college (as our romanced was blossoming), Mrs. FW and I drank prodigious amounts of the cheapest diet soda we could get our hands on. It was really awful, off-brand stuff. Think diet strawberry shasta… and you’ll get the picture. This essential fuel for all-night study sessions cost us $4 for a 30 can flat. We’d easily go through a flat per week during peak study season.
After college, being so mature and all, we quickly dialed back our soda consumption. But we missed the fizz! We were buying 2 liters of seltzer water occasionally, along with diet ginger ale. The reasons for diet ginger ale have been lost to the sands of time as I now think that stuff tastes weird even for diet soda. And, Mrs. FW was a known coke zero fiend.
When we moved to Washington, DC, we quickly discovered that the tap water there tastes terrible (we later learned that it also likely contained lead… but that’s another story. Thanks DC!) We got a brita filter, but we also upped our seltzer consumption. We knew it was becoming a problem when it took more than a single trip from the car into the house to carry our stash of 2L seltzer bottles. Our recycling bin runneth over.
One day I was browsing a favorite kitchen store in DC (Hill’s Kitchen, highly recommended!) and nearly stumbled over the sodastream display. I’d honestly never considered making our seltzer! The skies parted, angels sung, I texted Mrs. FW that I’d discovered the solution to all our problems, and I biked home with a sodastream machine strapped to my back.
Time passes, seltzer is made. Things are good. Too good, actually… Looking at our monthly spending I began to realize that we were spending more on seltzer per month with the sodastream than with bottled seltzer. Why? We were drinking mammoth amounts every month. Our peak seltzer consumption had us going through 180L per month. We’ve stopped all other beverages (no juice or soda), and so seltzer had become our drink du jour.
Think about that. 180 LITERS of seltzer. A standard American bathtub holds 150L of water. Mrs. FW and I drink more than a bathtub-full of seltzer every month!
That’s 3 full sodastream canisters of CO2, at $15 a pop (!!). The sodastream allowed us to consume way more seltzer than we ever would have if we were buying it in 2L bottles. There’s no way in soda-hades that I’d schlep 90 bottles of seltzer from the grocery store! But if it’s just 3 little canisters… it seems much more reasonable.
Now we love our seltzer. And ever since we started drinking it, we’ve been consuming way more water than we ever did before. We don’t add syrups or flavors, so it’s just water, but the cost, oh the cost! The concept of drinking a veritable river of seltzer a month isn’t bad, but the reality of spending $45/month or $540/year on bubbly water is sorta insane.
Knowing this was unsustainable, I began a quest for solutions. Commercial seltzer guns are pretty awesome, but also come with an intense list of supporting equipment. I also saw that some folks completely did away with the sodastream machine and bottles and built a bicycle tube valve and 2L bottle contraption that looked neat… but certainly didn’t pass the “could I live with this in my kitchen?” test.
Turns out, there’s a way to hook-up a big CO2 tank to a standard sodastream machine.
But, is it legal to convert a sodastream to use a bigger CO2 tank? Well, sodastream works on the classic economic model pioneered by Gillette razor blades. They sell the machine for cheap and then make their money on the consumables (CO2 canisters). To protect their slightly ridiculous pricing monopoly on CO2 refills, they technically don’t “sell” the canisters to you. You are “licensing” them from the company. Weird huh? That allows sodastream to sue companies that build refilling and conversion kits (Wikipedia has a great explanation of the entire legal strategy). The legal risk seems to rest entirely with the seller of this equipment, leaving the buyer (me!) in the clear. Whew!
Regardless of the risk, there are proprietors that sell the equipment necessary for a sodastream conversion. Enter these adapters and hoses for modding your sodastream. And so, without further pontificating, I present to you:
The Frugalwoods Step-by-Step Sodastream to 20lb CO2 Tank Conversion Process:
The parts needed for my sodastream conversion are pretty simple:
- Adapter, hose and pressure gauge. We bought ours several years ago from a now-defunct site, but these adaptor kits on ebay appear to be similar (UPDATED 1/25/19 with a new affiliate link).
- 20lb non-siphon CO2 tank from our local homebrewing store. This cost $175.31 the first time, but only $50 to swap it for a full one next time. It’s a little more expensive than getting it from a welding supply shop, but I can rest easy knowing that this CO2 tank is intended for beverage use. Probably doesn’t matter, but I figured it couldn’t hurt. Update: check out what we later learned…
The set-up steps are pretty straightforward:
Step 1: Use a drill to open up a hole in the back of the sodastream tower. The hole has to be large enough to fit the smallest fitting on your line.
Step 2: I used a chisel to enlarge and clean-up the hole in the back of the sodastream. You don’t want the edges to be sharp as that could cut your CO2 line, which would = bad news.
Step 3: The finished hole! That took all of 10 minutes to do. The hard stuff is over now!
Step 4: Screw on the sodastream side of the line. Once you’ve done that, thread the line and the quick-attach fitting through the hole you drilled/chiseled. Now put your sodastream back together:
Step 5: On to the CO2 tank! Follow the instructions that came with your adapter kit to add the fitting and gauge to the tank. Don’t forget to add the plastic washer! It goes between the fitting and the tank like so:
Step 6: Finally, attach the line to the gauge. Step back and admire your work:
Once Mrs. FW positioned the trash and recycling bins back in their places, the tank blended in pretty well with our kitchen. The hose is obvious but has turned out to be a great conversation starter!
But, how much is this going to save us?
Raw CO2 costs:
- Sodastream canister: $1.07/oz ($15 for a 14oz canister swap at our local hardware store)
- 20lb tank: $0.156/oz ($50 for 320oz, or 20lbs, at our local homebrew store)
Daaayyyuummm. Can you say retail markup? The raw CO2 is nearly 10x cheaper! Winning!
Assuming we continue to use 42oz of CO2 a month (3 sodastream canisters worth), our monthly CO2 cost is dramatically lower with our new system:
- (Old system) Sodastream: $45.00 / month
- (New system) Tank: $6.55 / month
We’re saving $38.45 a month, or $461.40 a year! (happy dance)
But remember, this system cost $253.10 (the 20lb CO2 tank cost $175.31, but includes $50 of consumable CO2 which I won’t count, so that’s $125.31).
Thus, $253.10 of system cost / $38.45 of monthly savings = 6.5 months. In other words, after 6 months we’ll be saving money over the old system of sodastream canisters!
Over 5 years? Well, we’ll use 2,700oz of CO2 over the next 5 years at our current rate, which would run us:
- $2,889.00 with sodastream canisters
- $421.2 with our new tank.
I am happy to spend $253 to save $2,467.80! Whoah.
(only 1 person has actually asked these questions to date, so they aren’t exactly frequent, but I imagine you might be wondering…)
Does the seltzer taste the same?
- Yes. There’s no discernible difference to our palettes. We didn’t do a blind taste test or anything, but we sniffed and sipped that first glass pretty darned carefully!
What does the pressure gauge tell you?
- It isn’t actually a good measure of how much CO2 is left in the tank. Why? The tank is mostly filled with liquid CO2. At the very top of the tank is the “air space” of gaseous CO2 above the level of the liquid. As you release the gas from the top of the tank, the pressure in the tank decreases. This decrease in pressure causes some of the liquid to change to gas, bringing the pressure back up to normal. The takeaway is that the pressure shown on the gauge will stay roughly the same as the liquid CO2 is used up. Once the liquid is gone, the pressure will rapidly decrease. That’s the indication that the tank needs to be swapped.
Why did you get such a long CO2 line?
- When I ordered the line and fittings, I wasn’t sure what size CO2 tank I wanted. If I’d gotten a 5lb or 10lb tank, I would have needed that extra length since they are much shorter. I don’t mind the line and Mrs. FW kindly tolerates it.
Am I going to blow myself up?
- Probably not? CO2 isn’t flammable, but even an inert gas pressurized to over 800 PSI is nothing to be cavalier about. As long as you don’t knock the stem off the tank (don’t drop it!) you’ll be fine.
Update: check out how our system is doing a year later and find out how we’re now saving even more on our hacked seltzer costs in The Great Homemade Seltzer Discovery of 2015!
Any other questions? Fire away and I’ll do my best to help!
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