Sparkling water comes from two very different places. Some of it bubbles up naturally from underground springs where volcanic activity forces carbon dioxide into the water deep below the earth’s surface. Most of what you buy in stores, though, is plain water that’s been carbonated in a factory by pumping pressurized CO2 gas into it. Both processes produce the same basic result: water with dissolved carbon dioxide that creates that familiar fizz.
How Nature Makes Sparkling Water
In certain geological hot spots, carbon dioxide gas produced by volcanic activity or the chemical breakdown of carbonate rocks seeps into underground water sources. The pressure deep underground keeps the gas dissolved in the water, much like a sealed bottle keeps soda fizzy. When that water eventually rises to the surface through springs or bore holes, the pressure drops and bubbles appear.
One of the best-known examples in the United States is the cluster of springs around Soda Springs, Idaho. There, carbonate rocks mix with slightly acidic groundwater, sending CO2 bubbles to the surface. Hooper Springs, the most famous of these, was considered one of the marvels of the Oregon Trail by westward emigrants. Visitors described the water as “bubbling and foaming like boiling water” with a taste like soda water. You can still visit the spring today and sample the naturally carbonated water in a city park. Similar geology produces naturally sparkling springs across parts of France, Italy, Germany, and Mexico.
Water from these sources picks up minerals as it travels through rock. To legally carry the label “mineral water” in the U.S., bottled water must contain at least 250 parts per million of total dissolved solids and come from a geologically protected underground source. If the label says “sparkling mineral water,” the carbonation must match what was present when the water emerged from the ground. Brands can recapture and re-inject the CO2 lost during bottling, but they can’t add more than the spring naturally produced.
How Factories Carbonate Water
The vast majority of sparkling water on store shelves is made through forced carbonation. A bottling plant starts with filtered or purified water, chills it (cold water absorbs CO2 more readily), and pumps pressurized carbon dioxide gas into a sealed vessel. In most industrial setups, the CO2 passes through a porous stone submerged in the water, breaking the gas into tiny bubbles that dissolve quickly and evenly throughout the liquid. The process is finished once the CO2 pressure in the water and the headspace above it reach equilibrium.
Forced carbonation is the industry standard because it’s fast, simple, and cheap. It requires just one step: connecting a CO2 tank to the pressurized vessel. The fizz level in the final product depends on two variables, the pressure of CO2 applied and the temperature of the water. Lower temperatures and higher pressures mean more carbonation. This is also why a warm can of sparkling water explodes more violently when opened: the gas it absorbed while cold can no longer stay dissolved at the higher temperature.
The First Artificial Sparkling Water
People drank naturally carbonated spring water for centuries before anyone figured out how to replicate it. In 1772, an English minister and amateur scientist named Joseph Priestley dripped sulfuric acid onto chalk, captured the carbon dioxide gas that fizzed off, and bubbled it through a column of water. He described the result as “an exceedingly pleasant sparkling water, resembling Seltzer water,” a reference to the famous naturally carbonated springs in Selters, Germany. The method earned him the Royal Society’s Copley Medal, its highest honor, and launched the commercial soda water industry within a few decades.
Seltzer, Club Soda, and Mineral Water
All three are sparkling, but they’re not the same product. Seltzer is the simplest: plain water with added CO2 and nothing else. Club soda starts the same way but includes added mineral salts like potassium sulfate, sodium chloride, sodium bicarbonate, and disodium phosphate. These give it a slightly salty, mineral-like taste meant to mimic the flavor of natural spring water. Sparkling mineral water, by contrast, gets its minerals from the underground source itself and must meet that 250 ppm dissolved solids threshold.
Tonic water is a different category entirely. It contains sugar (or artificial sweetener) and quinine, which gives it a bitter flavor. It’s closer to a soft drink than to sparkling water.
Does Sparkling Water Affect Your Teeth?
When CO2 dissolves in water, it forms a weak acid called carbonic acid. This drops the pH of plain sparkling water to somewhere between 4.18 and 5.87, depending on the brand and carbonation level. For context, tooth enamel begins to break down below a pH of about 5.5, which means some sparkling waters sit right at or below that threshold.
Lab studies have found that teeth exposed to plain carbonated water show more enamel erosion than teeth exposed to still water. That said, the effect is far milder than what sugary sodas or citrus juices produce, because sparkling water lacks the sugars and stronger acids that make those drinks particularly damaging. The practical risk from drinking plain sparkling water in normal amounts is small, but if you drink it all day long, you’re bathing your teeth in a mildly acidic solution for hours. Drinking it with meals rather than sipping throughout the day reduces that exposure.