You can’t add that pressure back, so ignore specialized gadgets that claim to do so. There’s one trick that really works though, and it’s a throwback to 5th-grade science class. We’re talking about solvents (liquids that can dissolve other substances) and solutes (substances that dissolve). In this case, the water is the solvent and the CO2 is the solute. Ever wonder why seltzer doesn’t look bubbly until you open it? That’s because the pressure causes the CO2 to dissolve in it. When it escapes, it makes bubbles. More dissolved CO2 means more bubbles. Cold temperatures also cause the gas to dissolve. So keeping your opened seltzer as cold as possible is the key to keeping it bubbly. Pretty simple actually.
Storing Your Seltzer
Store your half-finished Polar or Soda Stream canister in the coldest part of the fridge–that’s the back. Or use your leftovers to whip up one of these tasty recipes tasty recipe (yes, you can cook with seltzer!). Hint: it makes for the lightest pancakes in the entire world and delicious ice-cold gazpacho soup.