There is something amazing about making your own root beer, especially if you have kids. You take normal water, add a few ingredients, wait a few days and you have created a delicious, carbonated beverage.
When we make root beer here at home, we use plastic 2-liter and 3-liter soda bottles. These bottles have several advantages:
Easy to find
Easy to seal - just screw the cap on
They don't shatter if they explode like glass does
They are very strong, so they are less likely to explode
The problem that can occur when you make your own root beer is that it creates a lot of pressure in the bottle - enough pressure to shatter glass. The pressure comes from the carbon dioxide produced by the yeast. This is the same carbon dioxide that is going to carbonate the water and make it fizzy, but if the pressure gets too high the bottle can explode.
The following video nicely explains the steps to making root beer:
If making root beer in a 2-liter soda bottle, you need:
A clean 2-liter plastic bottle and cap
1/2 cup of sugar
1/8 teaspoon of yeast
1/2 tablespooon of root beer extract
The video suggests bakers yeast, but if you want to get fancy and cut back a little on the yeasty taste, you could use brewers yeast or champagne yeast that you can buy on the Internet or buy at a wine making store.
After you add all the ingredients to the bottle, put the bottle somewhere at room temperature so that, if it explodes, it will not make a mess. We put ours outside under the deck, but you might choose the basement, the garage, the shower stall, etc. Feel the bottle every day. After several days you will be able to feel pressure building inside the bottle. Now it is time to put the bottle in the refrigerator to slow the yeast way down with cold temperatures.
The first time you open the bottle, do it outside or over the sink. Open the bottle very slowly. Home made root beer has a tendency to over-carbonate. In other words, this could be the fizziest soda you have ever seen in your life. Opening it outside prevents a mess inside.
The video mentions alcohol. Why is that? It's because your root beer is made using the same fermentation process used to make real beer. The yeast that you added to the root beer eats sugar and produces carbon dioxide plus alcohol. We need the carbon dioxide, but the alcohol may not be welcome. When making real beer, the carbon dioxide is allowed to vent and the fermentation process is allowed to run a lot longer. So real beer might be 5% alcohol while root beer is around 0.5% alcohol. That is a minuscule amount of alcohol, but it is not zero.
You can use this same technique to make any kind of soda, as shown here:
While real root beer is made with yeast, and therefore a yeasty taste is appropriate, real soda (like Coke and Pepsi) is not. Think back to the old soda fountain in a drug store. The clerk mixed soda syrup (containing the sugar and flavorings) with soda water (carbonated water). No yeast was necessary. The modern version of the old soda fountain is something called the Soda Stream shown here: