Carbonation happens when carbon dioxide gas dissolves into liquid under pressure. You can create it at home using three different approaches: forcing CO2 into water mechanically, fermenting with yeast, or triggering a chemical reaction between an acid and a base. Each method produces the same result (dissolved CO2 that forms bubbles when pressure drops), but they differ in cost, equipment, and how much control you get over the final fizz.
Why Pressure and Temperature Matter
Carbon dioxide dissolves into water proportionally to the pressure applied. Double the pressure, and roughly twice as much CO2 will dissolve. This relationship, known as Henry’s law, is the entire basis of carbonation. At room temperature and normal atmospheric pressure, water holds almost no CO2, only about 1 milligram per liter. That’s why a sealed bottle stays fizzy and an open glass goes flat: once the cap comes off, the CO2 has nowhere to go but out.
Temperature matters just as much. Cold liquids absorb significantly more CO2 than warm ones. If you’ve ever opened a warm soda and had it foam everywhere, that’s because the liquid physically couldn’t hold its CO2 at that temperature once the pressure dropped. For any method of carbonation, chilling your liquid to around 2 to 6°C (35 to 43°F) before and during carbonation gives you noticeably better results.
Forced Carbonation With a CO2 Tank
This is the method commercial sodas and home soda makers use. You push pressurized CO2 gas directly into cold water. The simplest version is a countertop soda maker like a SodaStream, which uses small CO2 cartridges and a special bottle that locks into the machine. You press a button, gas flows into the water, and you have sparkling water in about 30 seconds.
For more control, homebrewers and serious soda makers use a CO2 tank connected to a pressure regulator and a sealed keg. You set the regulator to your target pressure (typically 30 to 40 PSI for a well-carbonated drink at refrigerator temperature), connect it to a keg of cold water or beverage, and let the CO2 absorb over 24 to 48 hours. Shaking the keg speeds this up dramatically, sometimes to under 10 minutes, because it increases the contact area between gas and liquid.
If you use this method, make sure any container you pressurize is rated for it. Standard PET plastic soda bottles can handle around 12 bar (about 174 PSI) before they rupture, which provides a wide safety margin above typical carbonation pressures. Glass bottles not designed for pressure are dangerous and should never be used with forced carbonation.
Natural Carbonation Through Fermentation
Yeast produces CO2 as a byproduct of eating sugar. This is how beer, champagne, and kombucha get their fizz naturally. The process is called bottle conditioning: you add a measured amount of sugar to a finished beverage, seal it in a pressure-rated bottle, and let yeast ferment that sugar inside the closed container. Since the CO2 has no way to escape, it dissolves into the liquid.
The standard ratio, according to the American Homebrewers Association, is 177 grams (3/4 cup) of corn sugar per 5-gallon batch to reach 2.25 to 2.5 volumes of CO2, which is roughly the carbonation level of a typical lager. “Volumes of CO2” is how brewers measure fizz: 2.5 volumes means each liter of liquid contains 2.5 liters of dissolved CO2.
You can scale this down for smaller batches. For a single 500 mL bottle, that works out to about 4 to 5 grams of sugar (roughly one level teaspoon). Dissolve the sugar in a small amount of boiled water first, add it to the bottle, cap it tightly, and store it at room temperature for one to two weeks. The warmer the environment, the faster fermentation completes, but anything between 18 and 24°C (65 to 75°F) works well. After conditioning, refrigerate the bottles. The cold helps the CO2 stay dissolved and settles the yeast to the bottom.
The risk with this method is over-carbonation. Too much sugar creates too much CO2, and bottles can explode. Always measure carefully, and use bottles designed for carbonated beverages: thick glass beer bottles with crown caps, flip-top Grolsch-style bottles, or PET plastic soda bottles.
Chemical Carbonation With Baking Soda and Acid
You can generate CO2 gas by combining baking soda (sodium bicarbonate) with an acid like citric acid, lemon juice, or vinegar. This is the classic science-fair volcano reaction, but it can also carbonate a drink.
The reaction between citric acid and baking soda produces carbon dioxide, water, and sodium citrate. The ideal ratio is 1.3 grams of baking soda for every 1 gram of citric acid. This uses up both ingredients completely, so you don’t end up with excess baking soda making your drink taste soapy, or excess acid making it too sour.
There are two ways to use this reaction for drinks. The simple way is to stir small amounts of baking soda directly into an acidic beverage (like lemonade) right before drinking. You’ll get a brief, light fizz, but it fades quickly and changes the flavor. The more effective approach is to generate the CO2 in a separate sealed container and pipe the gas into your chilled beverage through tubing. DIY setups using two connected bottles (one as the reaction chamber, one holding the drink) can work, though the carbonation will be lighter than what a pressurized tank delivers.
Chemical carbonation is fun for experiments but impractical for regular use. The fizz is weaker and harder to control compared to the other two methods.
How to Keep Your Drinks Fizzy Longer
Once you’ve carbonated a beverage, the CO2 starts escaping the moment pressure drops. At room temperature, the stable concentration of dissolved CO2 in an open drink is essentially zero, so all your carbonation will eventually leave. Here’s how to slow that down.
- Keep it cold. Cold liquid holds CO2 better. A refrigerated drink stays fizzy far longer than one sitting on a counter.
- Pour gently. Turbulent pouring creates millions of tiny bubbles all at once, releasing CO2 rapidly. Pouring slowly down the side of a tilted glass, the way servers pour champagne, preserves significantly more carbonation and can yield tens of thousands more bubbles over the life of the drink compared to a straight pour.
- Use smooth glasses. CO2 escapes through tiny imperfections on glass surfaces called nucleation sites. Scratches, dust, dried residue, and even dishwasher film all create spots where bubbles form and carry CO2 out of solution. A clean, smooth glass loses carbonation more slowly.
- Reseal quickly. If you’re not finishing the bottle, cap it immediately. Every second it’s open, CO2 is diffusing out of the liquid and into the air.
A Note on Tooth Enamel
Plain carbonated water is slightly acidic, typically landing between pH 3.6 and 5.9 depending on how heavily carbonated it is. Tooth enamel begins to soften at around pH 5.5. Lightly carbonated water often sits right at or slightly below that threshold, while heavily carbonated water drops well below it. Research published in the Korean Journal of Orthodontics found that carbonated water reduced enamel microhardness, with greater damage at higher carbonation levels. Adding calcium to the water cut enamel dissolution by roughly 50%, which may explain why mineral-rich sparkling waters like Perrier tend to score better in dental studies than carbonated purified water. If you’re drinking homemade sparkling water regularly, the practical move is to drink it with meals rather than sipping throughout the day, which limits the time your teeth spend in contact with the acid.