Carbonating Root Beer and Soft Drinks Overview 

Carbonation is a subject that can be cheap and relatively easy, or expensive and involved, and it mostly depends on your level of dedication, what you want to do with it, and taste.

There are 5 main ways to carbonate root beer or other soft drinks for the hobbyist - store bought carbonated water, yeast, a setzer bottle and CO2 charge, a CO2 canister with a carbonator cap and 2-liter bottle, or a CO2 canister with a keg.

1) Store bought carbonated water.  This is a good method, and it works ok with making root beer from extract if you can get the sugar to dissolve and the extract to mix without too much stirring and without boiling it or having to move it many times.  Each time you transfer from container to container you lose much of the carbonation.  As a result, this is really not a viable option if you are making root beer from scratch, but it works pretty well for extracts.  This is mostly self explained, so I won't go into it much.

2) Yeast carbonating.  When you put yeast in sugar water at room temperature, it will create carbon dioxide and alcohol, and carbonate the water it is in.  Similarly, if you put it in root beer or a soft drink, it will carbonate your root beer.  There are several advantages and disadvantages to this technique. The primary advantage is cost - yeast is very, very cheap, and you can get it anywhere from the grocery store to your local beer home brew shop. There are, however, a few disadvantages.

One disadvantage is that it adds a slight off taste to your root beer.  Depending on which yeast you use, you will get a different off flavor.  Ale yeasts add a beer flavor and smell to your root beer.  Champagne yeast adds a slight fruity flavor to your root beer.  Letting the yeast sit for a week or so in the refridgerator after it has carbonated will cause the yeast to crash out and will reduce the flavor it adds to the root beer, which helps some.  Personally, I have never successfully gotten rid of the flavor entirely, but I have gotten it to be drinkable.  I have not experimented that much with this method however, and there may be ways to use yeast without getting an off flavor.  That's something I intend to experiment with more at some point.

Another disadvantage to yeast is that to make yeast survive and carbonate your root beer, you must leave your root beer out at room temperature for a few days.  This can allow other bacteria in your root beer to grow, which can add some really nasty flavors to your root beer if you are not careful.  Therefore, whenever you use yeast, you must clean all of your equipment very thoroughly, boiling utensils, soaking bottles in a bleach solution, or using disinfecting solutions from your local beer brewing store.  If you take care, you can avoid flavors from other bacteria.

Yeast will also create alcohol in addition to the carbon dioxide.  If you cool your yeast as soon as the root beer is carbonated, this is not a problem, as the amount of alcohol will be incredibly small (less than that in glass of natural orange juice).  For example, this recipe is intended for teachers to use in their chemistry labs, which the children then drink. It was lab tested and proven to be between 0.35% and 0.5% alcohol. It is such a small amount it is not worth worrying about. Still, this is worrisome to some people.

Lastly, yeast is sort of unstable.  It will continue to create CO2 and pressure until you put it in the refridgerator (or with some yeasts, even the refridgerator isn't cool enough to stop it from carbonating).  If the pressure gets great enough, you can blow up bottles.  If they are glass bottles, that can be quite dangerous.  You don't want to be near a glass bottle that explodes.  Therefore, it is best to use plastic soda bottles when carbonating, so you can squeeze the bottle regularly to test the pressure.  Also, plastic soda bottles are less likely to explode, and if they do they will probably do less damage (you will end up with a mess for sure, but hopefully nothing embedded in your body and walls).  Some people do use glass bottles without any problem, but it is just something to watch out for and be careful of.

 With those seemingly many disadvantages, none of them are that great if you take care and know what they are ahead of time.  Many people use yeast and are quite fine with it, and I recommend it for people who want to be a hobby root beer brewer without too much cost.

 3) Using a setzer bottle with a CO2 charge. 

You can buy setzer bottles (also called soda syphons ) at places like Hoptech.com and Amazon.com .  These are bottles that look very much like the squirt bottles you might have seen on the 3 Stooges, that they used to squirt each other in the face with.  These bottles are usually around 1 liter, metal, have an attachment where you can attach a small CO2 charge , and a squeeze lever you can use to squirt the contents out through a nozzle on the front.  You buy the CO2 charges in packs of usually 6, 12, or 10, and they will charge one bottle each. 

You basically just fill the bottle with your root beer, attach the CO2 charge, let it sit in the fridge for a few days, and you should have carbonated root beer.  This is a very easy and somewhat inexpensive method for root beer.  I recommend this for people who don't like the yeast flavor.  The only disadvantage here, really, is that each CO2 charge comes out to around a buck or 50 cents, and that is nearly the cost of a full bottle of off brand root beer.  However, if you are doing this for fun as a hobby, that's not a bad price to pay for your own home made root beer.

 4) Using a CO2 canister with a carbonator cap.

This is the method I use most of the time.  You can buy small CO2 canisters at your local home brew store for around $100, and they will provide CO2 for many, many bottles of root beer.  You can usually refill them fairly cheaply as well.  I believe my home brew store charges around $30 to refill it, and I think I might be able to get that cheaper.  Carbonator caps, like the one here, cost around $15.  They fit on a normal 2-liter soda pop bottle and attach to the CO2 canister. 

You put your root beer in your 2-liter bottle and cool it in the fridge to near freezing.  Then hook it up to the CO2 canister and apply between 20-30lbs of pressure. Shake the bottle, and the bottle will get soft.  Apply pressure again.  Shake again.  Do that a few times and you will have carbonated root beer.  It's pretty easy, you get good tasting root beer out of it. Although it has higher up front cost, I think the long term cost is smaller than using a setzer bottle with CO2 charges.

5) Using a CO2 canister with a keg.  This is a method I haven't tried out yet, but I do have a keg and plan to try it soon.  This is only if you want a lot of root beer.  Kegs usually hold 5 gallons of root beer.  And, you have to keep them cool. 

Basically you put your root beer in the keg, apply presure from the CO2 canister, let it sit, cool, for a few days, and you will have carbonated root beer.  It's fairly simple, but in order to keep it cold you must put the keg and CO2 canister in your refridgerator, which can be hard to fit.  I have one that I can fit if I remove a few of the shelves.  Some people buy a separate fridge just for the keg.  I also know people who have drilled a hole through the side of the fridge to run their CO2 line, and kept the CO2 can outside the fridge. 

It's doable, but it can be expensive, especially if you have to buy another refridgerator.  Still, a used keg is not that expensive, and if you really, really like root beer and plan to go through a lot of it, this might be a good option.  This is also good for parties and family gatherings.

I plan to write more detailed instructions for carbonating with yeast, carbonating with a carbonator cap, and carbonating with a keg in the future.  For now, this is a basic overview of the basic ways to carbonate root beer or soft drinks for the home brewer.  Enjoy!

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