Picture of CO2 Generator
How to make CO2 or, more to the point, carbonated water. I used some empty soda bottles and bits left over from installing an inline filter on my ice-maker. The rest I picked up at the hardware store.

  • 1/4" O.D. plastic tubing (ice-maker tubing)
  • a 1.5L soda bottle
  • one or more 500 mL soda bottles
  • an inline valve for 1/4" plastic tubing
  • two 1/4" tube to 3/8" M adapters
  • two 3/8" F couplers
  • Teflon tape
  • active dry yeast
  • sugar

I wandered around the hardware store with the various pieces, trying different combinations until I came up with something that would work. You don't have to use these exact pieces. Just about anything similar will do.

Standard Disclaimer: Not liable for damages due to use or misuse. No warranties expressed or implied. For educational purposes only. Safety goggles may be required during use. Some belching may occur.

Step 1: Making the Connecting Tube

Picture of Making the Connecting Tube
The connecting tube consists of two soda bottle caps, tubing and an inline valve.

Assembly is pretty straightforward. Most of the connections are "quick-connect". No special tools required.

To attach the caps:
1. drill holes just large enough for the adapters
2. wrap the threads of the adapters with Teflon tape
3. use the couplers to tighten the adapter onto the cap

Note: I used brass couplers. I would've preferred plastic ones but couldn't find any.
cloud_bam9 months ago

Hey just a little heads up. The yeast will eventually die off. The fermentation process yields cO2 and alcohol. Once the alcohol content rises above 6-8% it will kill off normal bakers yeast. Upside is that you can now get drunk on your super ghetto sugar wine.

mrbob1231 year ago

Is there some way to transfer the carbon dioxide to another bottle or something?

mrbob1231 year ago

Does anybody know a way you could transfer the C02? Maybe to another bottle?

Jodex4 years ago
It's illegal to make that sugar, water and yeast thing here in Finland. It's called kilju or sugar wine (as wikipedia told)

misfist Jodex4 years ago
The sugar, water and yeast is used to create the CO2, which carbonates the beverage in a separate container. That mixture is not being drunk.
Jodex misfist4 years ago
I know that, but still, you're making that sugar wine there, eventhough you're not gonna drink it. Jus for an example: you can't make moonshine for fuel purposes, as I know.
It IS illegal to distill alcohol for fuel purposes without a permit, however, it is not illegal to ferment it. This process is completely different. Of course, I am only referring to U.S. law. Your mileage may vary.
I know that fermenting just something like beer or wine isn't illegal, but here in Finland (at least) it's illegal to make "wine" that has "no" flavour (yeast doesn't count as a flavour here). There are some laws that control when your wine is legal and when not.
Kringlur Jodex3 years ago
Jodex, just make it and not tell anyone. You can break the law in Finland too : Þ
Jodex Kringlur3 years ago
I know I could make it (and actually have tried making the drink, but I did it bad and didn't drink it), but I just mentioned that little thing.
555mst5556 years ago
hey...c'mon ppl pls dont do this.....ur'e contributing to GLOBAL WARMING!!!!...:(
NO. The CO2 is coming from the atmosphere so no change in the amount of CO2 in the atmosphere. The CO2 your thinking of is coming from the ground and going into the atmosphere.
no.....i mean...some kids make the baking soda and vinegar bomb thing.....it produces CO2....but by itself(not mixed) it's not made from CO2
Ah. I thought you meant the sugar. baking soda is mined from the ground. (where the CO2 comes from) so it would contribute slightly.
"contribute slightly" x the number of kids who made it = alot CO2

alot CO2 + more trees being chopped down =not enought trees absorbing the CO2
Global warming has no real scientific merit to begin with. The people who started the idea all had something to gain from it. If you do some research (Googling) you'll find more actual scientific evidence pointing to the fact that our sun goes through cycles of increased heat. The increased heat in turn affects our planet's atmospheric temperature and conditions. It's a natural process that has always occurred; otherwise the planet would be uninhabitable now =)
http://www.skepticalscience.com/pics/Solar_vs_Temp_basic.gif this graph shows it cannot be the sun but has to be something else.
"From the actual data we conclude that the graphs from Lockwood and Frölish were flawed:

1. The methodology used by Lockwood and Frölish to smooth the lines was applied only to maxima of R (sunspot number), dismissing the TSI. This practice hides the minima, which for the issue are more important than the maxima. For example, if the minimum of TSI in 1975 was 1365.5 W/m^2, it would contrast dramatically with the minimum of TSI of 1998 that was 1366 W/m^2 (0.033% higher). That would make the Sun in 1975 “colder” than in 1998. However, if we compare minimum values with maximum values, then the Sun would be frankly “warmer” in 1998 -when the solar energy output was 1366 W/m^2- than in 1975 -when the energy output was 1366.1111 W/m^2. Today (21/07/07), the global TSI was 1367.6744 W/m^2); hence, we see that we must not smooth maxima values through movable trends because we would be hiding the minima values, which are more important because the baseline of the “cooler” or lower nuclear activity of the Sun are higher everyday. The coolest period of the Sun happened during the Maunder Minimum when the TSI was 1363.5 W/m^2. The coolest period of the Sun from 1985 to date occurred in 1996 when the TSI was 1365.6211 W/m^2. An interesting blotch is that in 1985 the TSI was 1365.6506 W/m^2 and in 2000 was 1366.6744."

See the graph.

The temperature difference as a % and TSI differences as a %

Yes their is some correlation but on that data the temperature change has never been as far from the change in TSI for so long as the past few years.
its all carbon based so it's gonna be turned into something else next,like a diamond or a tree.
do you even know what co2 generators are for. they are to help grow plants. yes you creating co2 but only to turn it into oxygen. co2 generators are used by even the most die hard activists. its a good thing not a bad thing.
yeah....but still they're chopping down trees.....watch extreme loggers on discovery channel
yeah. i thought discovery channel is supporting planet green. so why do they have extreme loggers?
it's natural, yeast are living organisms! and even if every single human in the world, cows (thru uuh... expelling gas) will STILL contribute more co2 than this.
Wooo global warming!! Hot summers and cold winters... Bring on the CO2!!!
You should stop breathing to help save the planet
And you're trusting them scientists. Its not global warming, it's just the media making a big fuss. The world has been warming up for millions of years since the last ice age, anyway.
Thank you for saying that. Big fuss.
j626no JohnJY5 years ago
He could contribute to it... if it existed.
mooner774 years ago
If you want some really sturdy bottles that wont explode very easly then i suggest you use one of those big sturdy gatorade And powerade bottles.
TechDante4 years ago
what about using vinigar and baking soda would that not produce the same results in a fraction of the time/
baking soda + vinegar , yes, the same gas is produced, but less of it, and in a short burst, like a "puff" of co2, and the chemical reaction ends.

But because yeast are alive, this method can produce co2 for weeks, because the yeast are spending their lives dining on sugar as they are hungry.
excreting/exhaling co2 is the very process which differentiates an animal from a plant.
The colder you get the water that you're going to carbonate, the more CO2 it will absorb.
Get the water as cold as you can without freezing it before you attach the CO2 generator.
myfcr4 years ago
cool instructable, what about some extra tube making the CO@ bubble into the drink
goshinbi7 years ago
remember to not drink the yeast water it will contain alcohol.
Since this can be done in a matter of hours, it will contain VERY little alcohol. It would take almost a week for it to reach any significant level of alcohol, and with just sugar and water in the solution, the yeast would need yeast nutrients to be added for it to survive that long in the first place.
The amount of alcohol that is in the water does not depend on the time, but on the amount of sugar you have added and the type of yeast (some yeast strains can't handle high alcohol percentages very well)

Although I think I know what you want to say: If you only have a little yeast if will create alcohol (and CO2) but at a much slower rate. Therefor you need longer to create a lot of it, and because this is mostly sugar and water, your yeast would have diead by then.
...which is good stuff for alcoholics
ferment some coke for 3 days, drink it, and get sick...
you did, right?
nah, my dad did
Hmm. Alcohol... What kind?
ethanol and quite possibly methanol (the bad kind that causes harm found in bad moonshine)
Ok then *goes to wine making instructable*... Well it may be flammable (Bwahaha)
do you have to let it set for a while FIRE IS FUN!!!! FIRE FIRE FIRE!!!!!!!! *runs to grab a lighter*
And that's where I saw the leprechaun, he tells me to burn things.
Doesn't Chris say that on family guy? XD
No, thats Ralph on the simpsons
to make it flammable you need to distill it first
pdub77 lukeyj156 years ago
yeah this is pretty much the recipe for brewing cheap hobo-wine
pdub77 goshinbi6 years ago
yeah, nobody wants that stuff!
X_D_3_M_17 years ago
carbonated milk=carbonated cocoa puffs
samando7 years ago
hmmmmm...a few weeks g ago i was experimenting with the chemical reactions of acid and alkali when i suddenly managed to make a weird substance that seems to constantly output co2 even without water,and it's totally edible
I believe you where making hydrogen through the proses of eletrolasiss
wrong. and its "electrolysis" and it requires some electronics stuff to do.
You only need two specific metal rods ( I don't remember ) in water and pass electricity throuogh them, it's a middle school activity. Anyways, you put a lemon in toothpaste, it releases co2, you put soda in vinegar, that releases c02, thousand things do.
um.... the metal isn't quite as important as what you add to the water too make it conductive. Remember that pure water(distilled, not tap water) is a pretty good insulator so you'll need to add something to it.
The metal used are extremely important for electrolysis as the products formed are based on ions from the metals
Okay first. There is an unspoken rule in forums all over the internet. That rule is, don't revive a dead thread. As yo can see, the last comment on this thread was placed in 2008. It is currently 2010. Now, if you have proof (i.e. chemical formulas or descriptions of redox equations) that the metals used to conduct electricity are "extremely important" than please do not post. And now to reply to your comment.

In an electrolysis reaction, DC electricity is passed through a solution of water and an electrolyte. The conductors can be anything from copper to platinum( as found in real lab equipment) the metals do not contribute to the reaction and are not consumed by the reaction. Now, certain metals are better suited for electrolysis applications, for example metals that are easily oxidized such as copper or iron should not be used as the pure oxygen will react with the electrodes causing corrosion and reduced performance.

What I believe pyro-jim and DrCoolSanta are referring to is electroplating. It is very similar to electrolysis but instead of using electricity to separate water into hydrogen and oxygen, electroplating uses electricity to transfer, for example, chromium ions onto car bumpers. In this case, yes the metals used are "extremely important" as it is ions from the chromium negative electrode being deposited onto the positively charged bumper. These two processes look similar as they both use electrodes, electrolytes and electricity, but they are two distinct processes with two distinct products. One being gasses and the other bumpers.

I hope this helps quell the debate.
Sorry Techodude, i was on my ipod and didn't see the date. I think what I am referring to probably is electroplating it's just I have always been taught it as electrolysis. An example of what I mean is the purification of copper.
Well I just said that because we learnt it in school this way, two specific metals that I don't remember. Sorry for that . . .
zinc and copper, when we did it a some years back. idk if that is still what is being used. i remember also, alloys of melting the 1982-current pennies. copper and zinc. lol
Citric Acid and Bicarb soda and water work wonders. Good for cleaning too.
yeah, bicarb is also good for getting rid of smells put some in your frige, it works wonders!
Way ahead of you.
You add bicarb soda or salt but salt creates dangerous gases so don't use it.
i never heard the lemon+toothpaste one but with thiss stuff, it actually doesn't taste bad either and (obviously) it's totally fireproof
you can make stuff fireproof by soaking it in alum and water. (Potassium aluminium sulphate)
Most neutralization reactions of bases that contain the carbonate radiacal release CO2. Not sure about toothpaste, but atleast mine was a carbonate.
well... i dont know because I did some basic tests and whatever the gas is it isn't flammable
Pie Ninja5 years ago
Hey, carbonated water + Kool Aid or cordial = soda!
I use this to make carbonated watermelon kool Aid :) Its really good. So is carbonated lemonade  :)
Pie Ninja5 years ago
I think a 2L bottle can take up to 120 PSI.
Did this to make plain carbonated water (I love carbonated water, but it's so difficult to find and expensive, at least in the states). Used corn syrup instead of sugar. Note that unless you do something more than what the instructions say (and something more than I did), the resulting water will be /slightly/ funky from the yeast/alcohol/sugar/whatever mix. Not enough to make me not want to drink it, but enough to make me go "how did any of that make it from this bottle to this bottle?" I suppose the ethanol can vaporize to bother me.
Really? Over here in Australia you can get a 2L bottle of carbonatedwater for $2.00.
degroof (author) 5 years ago
Just for fun, I calculated the "carbon footprint" of this thing. Each 16oz bottle I fill contains approximately 2.5g of CO2. My car releases roughly 270g of CO2 per mile. The nearest store is 1 mile (2 mile round trip) from my house. So, the carbon footprint of driving to the store to buy soda is equivalent to filling (270x2/2.5) 216 bottles. Also, 200g of sugar plus 15g of yeast (costing about $1.20) seems to produce enough CO2 to fill about 20 16oz bottles. The same amount of club soda would cost about $10 at the store. So, for me at least, it works out to 12% the cost and 0.5% the carbon footprint, which isn't too bad as long as you don't mind the extra work.
you could add a oxygen stone to the water bottle cap it would help the co2 go into solution decreasing carbonation time you can find these in pet stores in the aquarium dept or your local home brew store.But really this is a cool idea
kikiclint6 years ago
you wont be able to just keep adding sugar because eventually the yeast will die from either too much CO2 buildup or alchohol forming in the the brewing container.
trumpkin7 years ago
couldn't you just use vinegar and baking soda to make co2? capture it in a balloon nad put into another bottle?
degroof (author) 7 years ago
It depends a lot on your needs. The baking soda and vinegar reaction is a lot faster, giving you a large amount of CO2 in seconds. The yeast process is a lot slower, taking a day or two to generate a reasonable amount of CO2 but it will continue to produce CO2 for a couple of weeks.
moomoocows7 years ago
Yes that's right actually there's an instructable that shows the baking soda and vinegar process.
just a thought, but you would generate more co2 with baking soda and vinegar using the same setup... or if you're worried about the taste use some baking soda and cacl2... they sell the stuff instead of rock-salt to melt ice... it just makes co2 salt and chalk...
DrCoolSanta7 years ago
you know why it doesn't work well, because co2 dissolves at its best at high pressure, and this would be normal pressore, but dont try increasing the pressure, bottle explosion.
Rockerx7 years ago
so depending on the liquid you use you get that flavor? and its safe to drink?
ilovetea7 years ago
Before I get the tubing is there anything else that I could carbonate with just the yeast and sugar water?
degroof (author)  ilovetea7 years ago
I usually stick to plain watter with a bit of lime but I've been experimenting with other drinks to. - coffee is really bad - orange juice works well - water, sugar and vanilla will get you a decent cream soda I've also used it to revive soda that's gone flat. As far as I can tell, just about every bottled soda uses the same sized cap.
brainiac7 years ago
love it for advance plant growins and soda but everything just...
dethshil7 years ago
OMG I just called Al Gore. Your destroying the planet with this. Stop soda consumption..CO2 which plants need to live is causing global warming...so says Al. This Instructable should be called..the Co2 generator of death 'aka carbon footprint destruction machine' aka greenhouse gas armegeddon where all gonna die a horrible death invention. OK...I'm not being serious..just humoring myself. Nice instructable
Tinker837 years ago
actually as far as reusing the mixture, after a while the alcohol content would get so high that it would start to kill the yeast and it would take progressively longer. if you were to split it and dilute with water you could keep it going - kind of like one of those generation bread mixes.
jolshefsky7 years ago
This is a fantastic idea. I liked the idea of making my own soda but the whole CO2 system made it cost too much. Plus I was making wine for a while but never exploited the CO2 ... maybe I can even attach it to my compressor tank and get free compressed air. Hmm. However, for anyone making this, I'd recommend buying tubing that is pressure-rated (i.e. polyethylene tubing is good for like 100 PSI or so), definitely add the pressure valve, and add a pressure release valve like on a compressor tank that releases at, say, 120PSI. The 2L bottle is probably good for 40PSI most of the time but won't burst until 200PSI or so (unless you whack it or damage it). That said, I might use a more durable vessel.
ive had bottles up to 120-125 and they usually explode right around there.
degroof (author)  jolshefsky7 years ago
I actually tried putting a spent helium tank (the disposable kind you get with balloons) in the system. Couldn't seem to build up enough pressure though. Either I didn't have a good seal on the tank or I just wasn't patient enough. The volume of the tank is huge compared with the soda bottle.
vaxjo7 years ago
Use grape juice instead of a sugar/water mix and when you're done carbonating bottles of water your yeast will have made you half a liter of hooch.

Just sayin'.
Ora7 years ago
Good improvement to this idea. I like the idea of the pressure gauge, and the T-valve seems like it would be helpful when disconnecting the hose from the bottles.