Open Bottles

• Opening a bottle is one of the fastest ways to cause soda to lose its fizz. Once opened, a bottle allows carbonation to escape quickly, and the soda will go completely flat in three days or less. Most modern soda brands and do-it-yourself soda kits include bottles with a cap that provides a hermetic seal to keep as much carbonation inside as possible.

Effects of Pressurization

• You're probably familiar with the signature hiss of a newly opened soda bottle, but that hiss indicates a quick release of carbonation, meaning the beverage is on its way to going flat. Shaking a soda bottle increases the pressure inside as the carbonation begins to escape the beverage. The pressure continues to build until a release is offered, the agitation stops, or all carbonation is separated from the drink itself. During times of extreme pressure, explosive release of carbonation can occur, making for an amusing scene that will render soda flat in moments, instead of days or months.

Storage Temperature

• To store sodas for longer than a few days, strive to keep the temperature steady and cool. Temperature fluctuations cause a loss of carbonation as the liquids and gasses in the bottle expand and contract. Lower temperatures help reduce agitation of the molecules and prevent natural loss of carbonation. High temperatures can result in up to 15 percent loss of carbonation in as little as 12 weeks. Keeping the bottles in a cool and temperature-stable environment helps ensure the fizz lasts for the full expected span of at least nine months.

Ultraviolet Exposure

• Bright light, and particularly ultraviolet light, can also reduce the fizz in soda bottles. Direct sunlight is especially bad for clear bottles, as it allows UV light to quickly act on the carbonation in the bottle. Leaving a soda bottle out in the sun, especially on a hot day, dramatically decreases its overall carbonation over time. Store bottles in a dark and cool area to keep your soda fresh and fizzy.