Introduction: CO2 Generator

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.

Step 2: Brewing Some CO2

Picture of Brewing Some CO2

Fill the 1.5L bottle halfway with warm water. Add sugar and yeast. Proportions aren't critical. I used roughly a cup of sugar and a tablespoon of yeast. Mix thoroughly.

Close the valve on the connecting tube. Attach one end to the 1.5L bottle but don't fully tighten it yet.

Squeeze as much air as possible out of the bottle, then tighten the cap. This will ensure that most of the gas you end up with is CO2.

Wait. It'll take hours for the CO2 to build up to a decent pressure. The bottle will eventually expand and become firm.

Note: There's a chance that the connecting tube will leak or pop apart. If you leave the bottle too long, it could explode. Both of these are potentially very messy.

Step 3: Filling a Bottle

Picture of Filling a Bottle

Take a 500mL bottle and fill it 3/4 full with cold water. Attach it to the free end of the connecting tube but don't tighten it fully.

Squeeze the air out and tighten the cap.

Open the valve. The bottle will expand and pressurize.

Shake the 500mL bottle to dissolve the CO2 in the water.

Close the valve and remove the cap.

You should now have a bottle of carbonated water. You can either drink it right away or cap it and store it in the fridge for later. Depending on how much pressure you've built up, you might be able to fill several bottles.

Note: Shaking the 1.5L bottle will help increase the pressure but take care not to get any of the yeast water in the tubing. It'll mess up the taste of the water.

The liquid doesn't have to be water. You can use orange juice and make orange soda. Or maybe some vanilla and sugar to make creme soda.

I'm not sure how renewable the CO2 source is. Presumably, you can just keep feeding the yeast sugar to make more CO2. I suspect, though, that the yeast will eventually die and you'll need to start a new batch.

Step 4: Pressure Gauge

Picture of Pressure Gauge

If you're feeling ambitious, you can add a T connector and a pressure gauge. I found that 30 psi is about right for filling a bottle. I'm not sure how much pressure this setup can contain. I may have to push it to the point of failure just to find out.

Update: The highest pressure I've managed so far is 70 psi.

My current rig has two yeast bottles, each with its own valve, and a master valve. This allows me to switch out one of the bottles while maintaining the pressure.


Spykerhond. (author)2016-07-08

I am thinking about a 24hr timer ,aquarium air pump, a large plastic reservoir tank and the yeast thing mounting the air pump on the outside sticking a pipe in the air intake base rubber of the pump to the tank. heh ? growers this is my first time , would that work ?

JamesG227 (author)2016-05-13

I have been thinking about carbonating drinks... the hardware is exactly what I was thinking, however, instead of using yeast, sugar and water, use white vinegar (very cheap and a baking soda. All you need is about 40 pounds of pressure, which can be achieved easily enough with a half bottle of vinegar and around 1/2 tsp soda. Everything would be much faster, so I recommend a quick connect on the reaction bottle.

cloud_bam (author)2014-11-11

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.

mrbob123 (author)2014-01-19

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

mrbob123 (author)2014-01-19

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

Jodex (author)2010-10-23

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 (author)Jodex2011-01-16

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 (author)misfist2011-01-16

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.

shadowofblood (author)Jodex2011-05-15

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.

Jodex (author)shadowofblood2011-05-18

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 (author)Jodex2012-01-12

Jodex, just make it and not tell anyone. You can break the law in Finland too : Þ

Jodex (author)Kringlur2012-01-13

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.

555mst555 (author)2009-07-18

hey...c'mon ppl pls dont do this.....ur'e contributing to GLOBAL WARMING!!!!...:(

catprog (author)555mst5552009-09-18

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.

555mst555 (author)catprog2009-09-18

no.....i mean...some kids make the baking soda and vinegar bomb produces CO2....but by itself(not mixed) it's not made from CO2

catprog (author)555mst5552009-09-18

Ah. I thought you meant the sugar. baking soda is mined from the ground. (where the CO2 comes from) so it would contribute slightly.

555mst555 (author)catprog2009-09-18

"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

shadowofblood (author)555mst5552011-05-16

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 =)

catprog (author)shadowofblood2011-05-16 this graph shows it cannot be the sun but has to be something else.

shadowofblood (author)catprog2011-08-25

"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."

catprog (author)shadowofblood2011-08-25

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.

chibiwind (author)catprog2009-10-15

its all carbon based so it's gonna be turned into something else next,like a diamond or a tree.

mas9779 (author)555mst5552009-07-27

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.

555mst555 (author)mas97792009-09-18

yeah....but still they're chopping down extreme loggers on discovery channel

beehard44 (author)555mst5552010-08-26

yeah. i thought discovery channel is supporting planet green. so why do they have extreme loggers?

beehard44 (author)555mst5552010-08-25

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.

pyro-jim (author)555mst5552010-07-19

Wooo global warming!! Hot summers and cold winters... Bring on the CO2!!!

monterto (author)555mst5552009-10-29

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.

JohnJY (author)gotanysparecake2009-09-24

Thank you for saying that. Big fuss.

j626no (author)JohnJY2009-10-04


JohnJY (author)555mst5552009-09-24

He could contribute to it... if it existed.

mooner77 (author)2011-08-18

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.

TechDante (author)2010-12-31

what about using vinigar and baking soda would that not produce the same results in a fraction of the time/

phlange (author)TechDante2011-08-15

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.

James_Fergason (author)2010-11-15

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.

myfcr (author)2010-10-29

cool instructable, what about some extra tube making the CO@ bubble into the drink

goshinbi (author)2008-03-22

remember to not drink the yeast water it will contain alcohol.

afterburner909 (author)goshinbi2009-04-24

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.

nieks (author)afterburner9092010-10-24

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.

beehard44 (author)goshinbi2010-07-24

...which is good stuff for alcoholics

ferment some coke for 3 days, drink it, and get sick...

you did, right?

nah, my dad did

Gamernotnerd (author)goshinbi2008-03-31

Hmm. Alcohol... What kind?

goshinbi (author)Gamernotnerd2008-04-02

ethanol and quite possibly methanol (the bad kind that causes harm found in bad moonshine)

Gamernotnerd (author)goshinbi2008-04-03

Ok then *goes to wine making instructable*... Well it may be flammable (Bwahaha)

twenglish1 (author)Gamernotnerd2008-08-29

do you have to let it set for a while FIRE IS FUN!!!! FIRE FIRE FIRE!!!!!!!! *runs to grab a lighter*

Pie Ninja (author)twenglish12009-10-14

And that's where I saw the leprechaun, he tells me to burn things.

zombiehunter96 (author)Pie Ninja2010-04-25

Doesn't Chris say that on family guy? XD

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